[RESEND,v17,5/5] iommu/arm-smmu: Add support for qcom, smmu-v2 variant

Submitted by Vivek Gautam on Nov. 16, 2018, 11:24 a.m.

Details

Message ID 20181116112430.31248-6-vivek.gautam@codeaurora.org
State New
Headers show
Series "iommu/arm-smmu: Add runtime pm/sleep support" ( rev: 1 ) in Freedreno

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Commit Message

Vivek Gautam Nov. 16, 2018, 11:24 a.m.
qcom,smmu-v2 is an arm,smmu-v2 implementation with specific
clock and power requirements.
On msm8996, multiple cores, viz. mdss, video, etc. use this
smmu. On sdm845, this smmu is used with gpu.
Add bindings for the same.

Signed-off-by: Vivek Gautam <vivek.gautam@codeaurora.org>
Reviewed-by: Rob Herring <robh@kernel.org>
Reviewed-by: Tomasz Figa <tfiga@chromium.org>
Tested-by: Srinivas Kandagatla <srinivas.kandagatla@linaro.org>
Reviewed-by: Robin Murphy <robin.murphy@arm.com>
---
 drivers/iommu/arm-smmu.c | 13 +++++++++++++
 1 file changed, 13 insertions(+)

Patch hide | download patch | download mbox

diff --git a/drivers/iommu/arm-smmu.c b/drivers/iommu/arm-smmu.c
index 2098c3141f5f..d315ca637097 100644
--- a/drivers/iommu/arm-smmu.c
+++ b/drivers/iommu/arm-smmu.c
@@ -120,6 +120,7 @@  enum arm_smmu_implementation {
 	GENERIC_SMMU,
 	ARM_MMU500,
 	CAVIUM_SMMUV2,
+	QCOM_SMMUV2,
 };
 
 struct arm_smmu_s2cr {
@@ -2026,6 +2027,17 @@  ARM_SMMU_MATCH_DATA(arm_mmu401, ARM_SMMU_V1_64K, GENERIC_SMMU);
 ARM_SMMU_MATCH_DATA(arm_mmu500, ARM_SMMU_V2, ARM_MMU500);
 ARM_SMMU_MATCH_DATA(cavium_smmuv2, ARM_SMMU_V2, CAVIUM_SMMUV2);
 
+static const char * const qcom_smmuv2_clks[] = {
+	"bus", "iface",
+};
+
+static const struct arm_smmu_match_data qcom_smmuv2 = {
+	.version = ARM_SMMU_V2,
+	.model = QCOM_SMMUV2,
+	.clks = qcom_smmuv2_clks,
+	.num_clks = ARRAY_SIZE(qcom_smmuv2_clks),
+};
+
 static const struct of_device_id arm_smmu_of_match[] = {
 	{ .compatible = "arm,smmu-v1", .data = &smmu_generic_v1 },
 	{ .compatible = "arm,smmu-v2", .data = &smmu_generic_v2 },
@@ -2033,6 +2045,7 @@  static const struct of_device_id arm_smmu_of_match[] = {
 	{ .compatible = "arm,mmu-401", .data = &arm_mmu401 },
 	{ .compatible = "arm,mmu-500", .data = &arm_mmu500 },
 	{ .compatible = "cavium,smmu-v2", .data = &cavium_smmuv2 },
+	{ .compatible = "qcom,smmu-v2", .data = &qcom_smmuv2 },
 	{ },
 };
 MODULE_DEVICE_TABLE(of, arm_smmu_of_match);

Comments

[+Thor]

On Fri, Nov 16, 2018 at 04:54:30PM +0530, Vivek Gautam wrote:
> qcom,smmu-v2 is an arm,smmu-v2 implementation with specific
> clock and power requirements.
> On msm8996, multiple cores, viz. mdss, video, etc. use this
> smmu. On sdm845, this smmu is used with gpu.
> Add bindings for the same.
> 
> Signed-off-by: Vivek Gautam <vivek.gautam@codeaurora.org>
> Reviewed-by: Rob Herring <robh@kernel.org>
> Reviewed-by: Tomasz Figa <tfiga@chromium.org>
> Tested-by: Srinivas Kandagatla <srinivas.kandagatla@linaro.org>
> Reviewed-by: Robin Murphy <robin.murphy@arm.com>
> ---
>  drivers/iommu/arm-smmu.c | 13 +++++++++++++
>  1 file changed, 13 insertions(+)
> 
> diff --git a/drivers/iommu/arm-smmu.c b/drivers/iommu/arm-smmu.c
> index 2098c3141f5f..d315ca637097 100644
> --- a/drivers/iommu/arm-smmu.c
> +++ b/drivers/iommu/arm-smmu.c
> @@ -120,6 +120,7 @@ enum arm_smmu_implementation {
>  	GENERIC_SMMU,
>  	ARM_MMU500,
>  	CAVIUM_SMMUV2,
> +	QCOM_SMMUV2,
>  };
>  
>  struct arm_smmu_s2cr {
> @@ -2026,6 +2027,17 @@ ARM_SMMU_MATCH_DATA(arm_mmu401, ARM_SMMU_V1_64K, GENERIC_SMMU);
>  ARM_SMMU_MATCH_DATA(arm_mmu500, ARM_SMMU_V2, ARM_MMU500);
>  ARM_SMMU_MATCH_DATA(cavium_smmuv2, ARM_SMMU_V2, CAVIUM_SMMUV2);
>  
> +static const char * const qcom_smmuv2_clks[] = {
> +	"bus", "iface",
> +};
> +
> +static const struct arm_smmu_match_data qcom_smmuv2 = {
> +	.version = ARM_SMMU_V2,
> +	.model = QCOM_SMMUV2,
> +	.clks = qcom_smmuv2_clks,
> +	.num_clks = ARRAY_SIZE(qcom_smmuv2_clks),
> +};

These seems redundant if we go down the route proposed by Thor, where we
just pull all of the clocks out of the device-tree. In which case, why
do we need this match_data at all?

Will
Hi Will,

On Wed, Nov 21, 2018 at 11:09 PM Will Deacon <will.deacon@arm.com> wrote:
>
> [+Thor]
>
> On Fri, Nov 16, 2018 at 04:54:30PM +0530, Vivek Gautam wrote:
> > qcom,smmu-v2 is an arm,smmu-v2 implementation with specific
> > clock and power requirements.
> > On msm8996, multiple cores, viz. mdss, video, etc. use this
> > smmu. On sdm845, this smmu is used with gpu.
> > Add bindings for the same.
> >
> > Signed-off-by: Vivek Gautam <vivek.gautam@codeaurora.org>
> > Reviewed-by: Rob Herring <robh@kernel.org>
> > Reviewed-by: Tomasz Figa <tfiga@chromium.org>
> > Tested-by: Srinivas Kandagatla <srinivas.kandagatla@linaro.org>
> > Reviewed-by: Robin Murphy <robin.murphy@arm.com>
> > ---
> >  drivers/iommu/arm-smmu.c | 13 +++++++++++++
> >  1 file changed, 13 insertions(+)
> >
> > diff --git a/drivers/iommu/arm-smmu.c b/drivers/iommu/arm-smmu.c
> > index 2098c3141f5f..d315ca637097 100644
> > --- a/drivers/iommu/arm-smmu.c
> > +++ b/drivers/iommu/arm-smmu.c
> > @@ -120,6 +120,7 @@ enum arm_smmu_implementation {
> >       GENERIC_SMMU,
> >       ARM_MMU500,
> >       CAVIUM_SMMUV2,
> > +     QCOM_SMMUV2,
> >  };
> >
> >  struct arm_smmu_s2cr {
> > @@ -2026,6 +2027,17 @@ ARM_SMMU_MATCH_DATA(arm_mmu401, ARM_SMMU_V1_64K, GENERIC_SMMU);
> >  ARM_SMMU_MATCH_DATA(arm_mmu500, ARM_SMMU_V2, ARM_MMU500);
> >  ARM_SMMU_MATCH_DATA(cavium_smmuv2, ARM_SMMU_V2, CAVIUM_SMMUV2);
> >
> > +static const char * const qcom_smmuv2_clks[] = {
> > +     "bus", "iface",
> > +};
> > +
> > +static const struct arm_smmu_match_data qcom_smmuv2 = {
> > +     .version = ARM_SMMU_V2,
> > +     .model = QCOM_SMMUV2,
> > +     .clks = qcom_smmuv2_clks,
> > +     .num_clks = ARRAY_SIZE(qcom_smmuv2_clks),
> > +};
>
> These seems redundant if we go down the route proposed by Thor, where we
> just pull all of the clocks out of the device-tree. In which case, why
> do we need this match_data at all?

Which is better? Driver relying solely on the device tree to tell
which all clocks
are required to be enabled,
or, the driver deciding itself based on the platform's match data,
that it should
have X, Y, & Z clocks that should be supplied from the device tree.

Thanks
Vivek

>
> Will
> _______________________________________________
> iommu mailing list
> iommu@lists.linux-foundation.org
> https://lists.linuxfoundation.org/mailman/listinfo/iommu
Hi Vivek, Will,

On Fri, Nov 23, 2018 at 6:13 PM Vivek Gautam
<vivek.gautam@codeaurora.org> wrote:
>
> Hi Will,
>
> On Wed, Nov 21, 2018 at 11:09 PM Will Deacon <will.deacon@arm.com> wrote:
> >
> > [+Thor]
> >
> > On Fri, Nov 16, 2018 at 04:54:30PM +0530, Vivek Gautam wrote:
> > > qcom,smmu-v2 is an arm,smmu-v2 implementation with specific
> > > clock and power requirements.
> > > On msm8996, multiple cores, viz. mdss, video, etc. use this
> > > smmu. On sdm845, this smmu is used with gpu.
> > > Add bindings for the same.
> > >
> > > Signed-off-by: Vivek Gautam <vivek.gautam@codeaurora.org>
> > > Reviewed-by: Rob Herring <robh@kernel.org>
> > > Reviewed-by: Tomasz Figa <tfiga@chromium.org>
> > > Tested-by: Srinivas Kandagatla <srinivas.kandagatla@linaro.org>
> > > Reviewed-by: Robin Murphy <robin.murphy@arm.com>
> > > ---
> > >  drivers/iommu/arm-smmu.c | 13 +++++++++++++
> > >  1 file changed, 13 insertions(+)
> > >
> > > diff --git a/drivers/iommu/arm-smmu.c b/drivers/iommu/arm-smmu.c
> > > index 2098c3141f5f..d315ca637097 100644
> > > --- a/drivers/iommu/arm-smmu.c
> > > +++ b/drivers/iommu/arm-smmu.c
> > > @@ -120,6 +120,7 @@ enum arm_smmu_implementation {
> > >       GENERIC_SMMU,
> > >       ARM_MMU500,
> > >       CAVIUM_SMMUV2,
> > > +     QCOM_SMMUV2,
> > >  };
> > >
> > >  struct arm_smmu_s2cr {
> > > @@ -2026,6 +2027,17 @@ ARM_SMMU_MATCH_DATA(arm_mmu401, ARM_SMMU_V1_64K, GENERIC_SMMU);
> > >  ARM_SMMU_MATCH_DATA(arm_mmu500, ARM_SMMU_V2, ARM_MMU500);
> > >  ARM_SMMU_MATCH_DATA(cavium_smmuv2, ARM_SMMU_V2, CAVIUM_SMMUV2);
> > >
> > > +static const char * const qcom_smmuv2_clks[] = {
> > > +     "bus", "iface",
> > > +};
> > > +
> > > +static const struct arm_smmu_match_data qcom_smmuv2 = {
> > > +     .version = ARM_SMMU_V2,
> > > +     .model = QCOM_SMMUV2,
> > > +     .clks = qcom_smmuv2_clks,
> > > +     .num_clks = ARRAY_SIZE(qcom_smmuv2_clks),
> > > +};
> >
> > These seems redundant if we go down the route proposed by Thor, where we
> > just pull all of the clocks out of the device-tree. In which case, why
> > do we need this match_data at all?
>
> Which is better? Driver relying solely on the device tree to tell
> which all clocks
> are required to be enabled,
> or, the driver deciding itself based on the platform's match data,
> that it should
> have X, Y, & Z clocks that should be supplied from the device tree.

The former would simplify the driver, but would also make it
impossible to spot mistakes in DT, which would ultimately surface out
as very hard to debug bugs (likely complete system lockups).

For qcom_smmuv2, I believe we're eventually going to end up with
platform-specific quirks anyway, so specifying the clocks too wouldn't
hurt. Given that, I'd recommend sticking to the latter, i.e. what this
patch does.

Best regards,
Tomasz
Hi Tomasz,

On Fri, Nov 23, 2018 at 2:52 PM Tomasz Figa <tfiga@chromium.org> wrote:
>
> Hi Vivek, Will,
>
> On Fri, Nov 23, 2018 at 6:13 PM Vivek Gautam
> <vivek.gautam@codeaurora.org> wrote:
> >
> > Hi Will,
> >
> > On Wed, Nov 21, 2018 at 11:09 PM Will Deacon <will.deacon@arm.com> wrote:
> > >
> > > [+Thor]
> > >
> > > On Fri, Nov 16, 2018 at 04:54:30PM +0530, Vivek Gautam wrote:
> > > > qcom,smmu-v2 is an arm,smmu-v2 implementation with specific
> > > > clock and power requirements.
> > > > On msm8996, multiple cores, viz. mdss, video, etc. use this
> > > > smmu. On sdm845, this smmu is used with gpu.
> > > > Add bindings for the same.
> > > >
> > > > Signed-off-by: Vivek Gautam <vivek.gautam@codeaurora.org>
> > > > Reviewed-by: Rob Herring <robh@kernel.org>
> > > > Reviewed-by: Tomasz Figa <tfiga@chromium.org>
> > > > Tested-by: Srinivas Kandagatla <srinivas.kandagatla@linaro.org>
> > > > Reviewed-by: Robin Murphy <robin.murphy@arm.com>
> > > > ---
> > > >  drivers/iommu/arm-smmu.c | 13 +++++++++++++
> > > >  1 file changed, 13 insertions(+)
> > > >
> > > > diff --git a/drivers/iommu/arm-smmu.c b/drivers/iommu/arm-smmu.c
> > > > index 2098c3141f5f..d315ca637097 100644
> > > > --- a/drivers/iommu/arm-smmu.c
> > > > +++ b/drivers/iommu/arm-smmu.c
> > > > @@ -120,6 +120,7 @@ enum arm_smmu_implementation {
> > > >       GENERIC_SMMU,
> > > >       ARM_MMU500,
> > > >       CAVIUM_SMMUV2,
> > > > +     QCOM_SMMUV2,
> > > >  };
> > > >
> > > >  struct arm_smmu_s2cr {
> > > > @@ -2026,6 +2027,17 @@ ARM_SMMU_MATCH_DATA(arm_mmu401, ARM_SMMU_V1_64K, GENERIC_SMMU);
> > > >  ARM_SMMU_MATCH_DATA(arm_mmu500, ARM_SMMU_V2, ARM_MMU500);
> > > >  ARM_SMMU_MATCH_DATA(cavium_smmuv2, ARM_SMMU_V2, CAVIUM_SMMUV2);
> > > >
> > > > +static const char * const qcom_smmuv2_clks[] = {
> > > > +     "bus", "iface",
> > > > +};
> > > > +
> > > > +static const struct arm_smmu_match_data qcom_smmuv2 = {
> > > > +     .version = ARM_SMMU_V2,
> > > > +     .model = QCOM_SMMUV2,
> > > > +     .clks = qcom_smmuv2_clks,
> > > > +     .num_clks = ARRAY_SIZE(qcom_smmuv2_clks),
> > > > +};
> > >
> > > These seems redundant if we go down the route proposed by Thor, where we
> > > just pull all of the clocks out of the device-tree. In which case, why
> > > do we need this match_data at all?
> >
> > Which is better? Driver relying solely on the device tree to tell
> > which all clocks
> > are required to be enabled,
> > or, the driver deciding itself based on the platform's match data,
> > that it should
> > have X, Y, & Z clocks that should be supplied from the device tree.
>
> The former would simplify the driver, but would also make it
> impossible to spot mistakes in DT, which would ultimately surface out
> as very hard to debug bugs (likely complete system lockups).

Thanks.
Yea, this is how I understand things presently. Relying on device tree
puts the things out of driver's control.

Hi Will,
Am I unable to understand the intentions here for Thor's clock-fetch
design change?

>
> For qcom_smmuv2, I believe we're eventually going to end up with
> platform-specific quirks anyway, so specifying the clocks too wouldn't
> hurt. Given that, I'd recommend sticking to the latter, i.e. what this
> patch does.
>
> Best regards,
> Tomasz


Best regards
Vivek

> _______________________________________________
> iommu mailing list
> iommu@lists.linux-foundation.org
> https://lists.linuxfoundation.org/mailman/listinfo/iommu
On Fri, Nov 23, 2018 at 03:06:29PM +0530, Vivek Gautam wrote:
> On Fri, Nov 23, 2018 at 2:52 PM Tomasz Figa <tfiga@chromium.org> wrote:
> > On Fri, Nov 23, 2018 at 6:13 PM Vivek Gautam
> > <vivek.gautam@codeaurora.org> wrote:
> > > On Wed, Nov 21, 2018 at 11:09 PM Will Deacon <will.deacon@arm.com> wrote:
> > > > On Fri, Nov 16, 2018 at 04:54:30PM +0530, Vivek Gautam wrote:
> > > > > @@ -2026,6 +2027,17 @@ ARM_SMMU_MATCH_DATA(arm_mmu401, ARM_SMMU_V1_64K, GENERIC_SMMU);
> > > > >  ARM_SMMU_MATCH_DATA(arm_mmu500, ARM_SMMU_V2, ARM_MMU500);
> > > > >  ARM_SMMU_MATCH_DATA(cavium_smmuv2, ARM_SMMU_V2, CAVIUM_SMMUV2);
> > > > >
> > > > > +static const char * const qcom_smmuv2_clks[] = {
> > > > > +     "bus", "iface",
> > > > > +};
> > > > > +
> > > > > +static const struct arm_smmu_match_data qcom_smmuv2 = {
> > > > > +     .version = ARM_SMMU_V2,
> > > > > +     .model = QCOM_SMMUV2,
> > > > > +     .clks = qcom_smmuv2_clks,
> > > > > +     .num_clks = ARRAY_SIZE(qcom_smmuv2_clks),
> > > > > +};
> > > >
> > > > These seems redundant if we go down the route proposed by Thor, where we
> > > > just pull all of the clocks out of the device-tree. In which case, why
> > > > do we need this match_data at all?
> > >
> > > Which is better? Driver relying solely on the device tree to tell
> > > which all clocks
> > > are required to be enabled,
> > > or, the driver deciding itself based on the platform's match data,
> > > that it should
> > > have X, Y, & Z clocks that should be supplied from the device tree.
> >
> > The former would simplify the driver, but would also make it
> > impossible to spot mistakes in DT, which would ultimately surface out
> > as very hard to debug bugs (likely complete system lockups).
> 
> Thanks.
> Yea, this is how I understand things presently. Relying on device tree
> puts the things out of driver's control.

But it also has the undesirable effect of having to update the driver
code whenever we want to add support for a new SMMU implementation. If
we do this all in the DT, as Thor is trying to do, then older kernels
will work well with new hardware.

> Hi Will,
> Am I unable to understand the intentions here for Thor's clock-fetch
> design change?

I'm having trouble parsing your question, sorry. Please work with Thor
so that we have a single way to get the clock information. My preference
is to take it from the firmware, for the reason I stated above.

Will
On Sat, Nov 24, 2018 at 3:34 AM Will Deacon <will.deacon@arm.com> wrote:
>
> On Fri, Nov 23, 2018 at 03:06:29PM +0530, Vivek Gautam wrote:
> > On Fri, Nov 23, 2018 at 2:52 PM Tomasz Figa <tfiga@chromium.org> wrote:
> > > On Fri, Nov 23, 2018 at 6:13 PM Vivek Gautam
> > > <vivek.gautam@codeaurora.org> wrote:
> > > > On Wed, Nov 21, 2018 at 11:09 PM Will Deacon <will.deacon@arm.com> wrote:
> > > > > On Fri, Nov 16, 2018 at 04:54:30PM +0530, Vivek Gautam wrote:
> > > > > > @@ -2026,6 +2027,17 @@ ARM_SMMU_MATCH_DATA(arm_mmu401, ARM_SMMU_V1_64K, GENERIC_SMMU);
> > > > > >  ARM_SMMU_MATCH_DATA(arm_mmu500, ARM_SMMU_V2, ARM_MMU500);
> > > > > >  ARM_SMMU_MATCH_DATA(cavium_smmuv2, ARM_SMMU_V2, CAVIUM_SMMUV2);
> > > > > >
> > > > > > +static const char * const qcom_smmuv2_clks[] = {
> > > > > > +     "bus", "iface",
> > > > > > +};
> > > > > > +
> > > > > > +static const struct arm_smmu_match_data qcom_smmuv2 = {
> > > > > > +     .version = ARM_SMMU_V2,
> > > > > > +     .model = QCOM_SMMUV2,
> > > > > > +     .clks = qcom_smmuv2_clks,
> > > > > > +     .num_clks = ARRAY_SIZE(qcom_smmuv2_clks),
> > > > > > +};
> > > > >
> > > > > These seems redundant if we go down the route proposed by Thor, where we
> > > > > just pull all of the clocks out of the device-tree. In which case, why
> > > > > do we need this match_data at all?
> > > >
> > > > Which is better? Driver relying solely on the device tree to tell
> > > > which all clocks
> > > > are required to be enabled,
> > > > or, the driver deciding itself based on the platform's match data,
> > > > that it should
> > > > have X, Y, & Z clocks that should be supplied from the device tree.
> > >
> > > The former would simplify the driver, but would also make it
> > > impossible to spot mistakes in DT, which would ultimately surface out
> > > as very hard to debug bugs (likely complete system lockups).
> >
> > Thanks.
> > Yea, this is how I understand things presently. Relying on device tree
> > puts the things out of driver's control.
>
> But it also has the undesirable effect of having to update the driver
> code whenever we want to add support for a new SMMU implementation. If
> we do this all in the DT, as Thor is trying to do, then older kernels
> will work well with new hardware.

Fair enough, if you're okay with that. Obviously one would still have
to change the DT bindings to list the exact set of clocks for the new
hardware variant, unless the convention changed recently.

Best regards,
Tomasz
On 11/24/2018 12:04 AM, Will Deacon wrote:
> On Fri, Nov 23, 2018 at 03:06:29PM +0530, Vivek Gautam wrote:
>> On Fri, Nov 23, 2018 at 2:52 PM Tomasz Figa <tfiga@chromium.org> wrote:
>>> On Fri, Nov 23, 2018 at 6:13 PM Vivek Gautam
>>> <vivek.gautam@codeaurora.org> wrote:
>>>> On Wed, Nov 21, 2018 at 11:09 PM Will Deacon <will.deacon@arm.com> wrote:
>>>>> On Fri, Nov 16, 2018 at 04:54:30PM +0530, Vivek Gautam wrote:
>>>>>> @@ -2026,6 +2027,17 @@ ARM_SMMU_MATCH_DATA(arm_mmu401, ARM_SMMU_V1_64K, GENERIC_SMMU);
>>>>>>   ARM_SMMU_MATCH_DATA(arm_mmu500, ARM_SMMU_V2, ARM_MMU500);
>>>>>>   ARM_SMMU_MATCH_DATA(cavium_smmuv2, ARM_SMMU_V2, CAVIUM_SMMUV2);
>>>>>>
>>>>>> +static const char * const qcom_smmuv2_clks[] = {
>>>>>> +     "bus", "iface",
>>>>>> +};
>>>>>> +
>>>>>> +static const struct arm_smmu_match_data qcom_smmuv2 = {
>>>>>> +     .version = ARM_SMMU_V2,
>>>>>> +     .model = QCOM_SMMUV2,
>>>>>> +     .clks = qcom_smmuv2_clks,
>>>>>> +     .num_clks = ARRAY_SIZE(qcom_smmuv2_clks),
>>>>>> +};
>>>>> These seems redundant if we go down the route proposed by Thor, where we
>>>>> just pull all of the clocks out of the device-tree. In which case, why
>>>>> do we need this match_data at all?
>>>> Which is better? Driver relying solely on the device tree to tell
>>>> which all clocks
>>>> are required to be enabled,
>>>> or, the driver deciding itself based on the platform's match data,
>>>> that it should
>>>> have X, Y, & Z clocks that should be supplied from the device tree.
>>> The former would simplify the driver, but would also make it
>>> impossible to spot mistakes in DT, which would ultimately surface out
>>> as very hard to debug bugs (likely complete system lockups).
>> Thanks.
>> Yea, this is how I understand things presently. Relying on device tree
>> puts the things out of driver's control.
> But it also has the undesirable effect of having to update the driver
> code whenever we want to add support for a new SMMU implementation. If
> we do this all in the DT, as Thor is trying to do, then older kernels
> will work well with new hardware.
>
>> Hi Will,
>> Am I unable to understand the intentions here for Thor's clock-fetch
>> design change?
> I'm having trouble parsing your question, sorry. Please work with Thor
> so that we have a single way to get the clock information. My preference
> is to take it from the firmware, for the reason I stated above.
Hi Will,

Sure, thanks. I will work with Thor to get this going.

Hi Thor,
Does it sound okay to you to squash your patch [1] into my patch [2] with
your 'Signed-off-by' tag?
I will update the commit log to include the information about getting
clock details from device tree.

[1] https://patchwork.kernel.org/patch/10628725/
[2] https://patchwork.kernel.org/patch/10686061/

Best regards
Vivek
>
> Will
Hi Vivek,

On 11/26/18 4:55 AM, Vivek Gautam wrote:
> 
> On 11/24/2018 12:04 AM, Will Deacon wrote:
>> On Fri, Nov 23, 2018 at 03:06:29PM +0530, Vivek Gautam wrote:
>>> On Fri, Nov 23, 2018 at 2:52 PM Tomasz Figa <tfiga@chromium.org> wrote:
>>>> On Fri, Nov 23, 2018 at 6:13 PM Vivek Gautam
>>>> <vivek.gautam@codeaurora.org> wrote:
>>>>> On Wed, Nov 21, 2018 at 11:09 PM Will Deacon <will.deacon@arm.com> 
>>>>> wrote:
>>>>>> On Fri, Nov 16, 2018 at 04:54:30PM +0530, Vivek Gautam wrote:
>>>>>>> @@ -2026,6 +2027,17 @@ ARM_SMMU_MATCH_DATA(arm_mmu401, 
>>>>>>> ARM_SMMU_V1_64K, GENERIC_SMMU);
>>>>>>>   ARM_SMMU_MATCH_DATA(arm_mmu500, ARM_SMMU_V2, ARM_MMU500);
>>>>>>>   ARM_SMMU_MATCH_DATA(cavium_smmuv2, ARM_SMMU_V2, CAVIUM_SMMUV2);
>>>>>>>
>>>>>>> +static const char * const qcom_smmuv2_clks[] = {
>>>>>>> +     "bus", "iface",
>>>>>>> +};
>>>>>>> +
>>>>>>> +static const struct arm_smmu_match_data qcom_smmuv2 = {
>>>>>>> +     .version = ARM_SMMU_V2,
>>>>>>> +     .model = QCOM_SMMUV2,
>>>>>>> +     .clks = qcom_smmuv2_clks,
>>>>>>> +     .num_clks = ARRAY_SIZE(qcom_smmuv2_clks),
>>>>>>> +};
>>>>>> These seems redundant if we go down the route proposed by Thor, 
>>>>>> where we
>>>>>> just pull all of the clocks out of the device-tree. In which case, 
>>>>>> why
>>>>>> do we need this match_data at all?
>>>>> Which is better? Driver relying solely on the device tree to tell
>>>>> which all clocks
>>>>> are required to be enabled,
>>>>> or, the driver deciding itself based on the platform's match data,
>>>>> that it should
>>>>> have X, Y, & Z clocks that should be supplied from the device tree.
>>>> The former would simplify the driver, but would also make it
>>>> impossible to spot mistakes in DT, which would ultimately surface out
>>>> as very hard to debug bugs (likely complete system lockups).
>>> Thanks.
>>> Yea, this is how I understand things presently. Relying on device tree
>>> puts the things out of driver's control.
>> But it also has the undesirable effect of having to update the driver
>> code whenever we want to add support for a new SMMU implementation. If
>> we do this all in the DT, as Thor is trying to do, then older kernels
>> will work well with new hardware.
>>
>>> Hi Will,
>>> Am I unable to understand the intentions here for Thor's clock-fetch
>>> design change?
>> I'm having trouble parsing your question, sorry. Please work with Thor
>> so that we have a single way to get the clock information. My preference
>> is to take it from the firmware, for the reason I stated above.
> Hi Will,
> 
> Sure, thanks. I will work with Thor to get this going.
> 
> Hi Thor,
> Does it sound okay to you to squash your patch [1] into my patch [2] with
> your 'Signed-off-by' tag?
> I will update the commit log to include the information about getting
> clock details from device tree.
> 
> [1] https://patchwork.kernel.org/patch/10628725/
> [2] https://patchwork.kernel.org/patch/10686061/
> 

Yes, that would be great and easier to understand than my patch on top 
of yours.

Additionally, can you remove the "Error:" as Will requested as part of 
the squash?

Thank you!

Thor

> Best regards
> Vivek
>>
>> Will
> 
>
Hi Thor,


On 11/26/2018 8:11 PM, Thor Thayer wrote:
> Hi Vivek,
>
> On 11/26/18 4:55 AM, Vivek Gautam wrote:
>>
>> On 11/24/2018 12:04 AM, Will Deacon wrote:
>>> On Fri, Nov 23, 2018 at 03:06:29PM +0530, Vivek Gautam wrote:
>>>> On Fri, Nov 23, 2018 at 2:52 PM Tomasz Figa <tfiga@chromium.org> 
>>>> wrote:
>>>>> On Fri, Nov 23, 2018 at 6:13 PM Vivek Gautam
>>>>> <vivek.gautam@codeaurora.org> wrote:
>>>>>> On Wed, Nov 21, 2018 at 11:09 PM Will Deacon 
>>>>>> <will.deacon@arm.com> wrote:
>>>>>>> On Fri, Nov 16, 2018 at 04:54:30PM +0530, Vivek Gautam wrote:
>>>>>>>> @@ -2026,6 +2027,17 @@ ARM_SMMU_MATCH_DATA(arm_mmu401, 
>>>>>>>> ARM_SMMU_V1_64K, GENERIC_SMMU);
>>>>>>>>   ARM_SMMU_MATCH_DATA(arm_mmu500, ARM_SMMU_V2, ARM_MMU500);
>>>>>>>>   ARM_SMMU_MATCH_DATA(cavium_smmuv2, ARM_SMMU_V2, CAVIUM_SMMUV2);
>>>>>>>>
>>>>>>>> +static const char * const qcom_smmuv2_clks[] = {
>>>>>>>> +     "bus", "iface",
>>>>>>>> +};
>>>>>>>> +
>>>>>>>> +static const struct arm_smmu_match_data qcom_smmuv2 = {
>>>>>>>> +     .version = ARM_SMMU_V2,
>>>>>>>> +     .model = QCOM_SMMUV2,
>>>>>>>> +     .clks = qcom_smmuv2_clks,
>>>>>>>> +     .num_clks = ARRAY_SIZE(qcom_smmuv2_clks),
>>>>>>>> +};
>>>>>>> These seems redundant if we go down the route proposed by Thor, 
>>>>>>> where we
>>>>>>> just pull all of the clocks out of the device-tree. In which 
>>>>>>> case, why
>>>>>>> do we need this match_data at all?
>>>>>> Which is better? Driver relying solely on the device tree to tell
>>>>>> which all clocks
>>>>>> are required to be enabled,
>>>>>> or, the driver deciding itself based on the platform's match data,
>>>>>> that it should
>>>>>> have X, Y, & Z clocks that should be supplied from the device tree.
>>>>> The former would simplify the driver, but would also make it
>>>>> impossible to spot mistakes in DT, which would ultimately surface out
>>>>> as very hard to debug bugs (likely complete system lockups).
>>>> Thanks.
>>>> Yea, this is how I understand things presently. Relying on device tree
>>>> puts the things out of driver's control.
>>> But it also has the undesirable effect of having to update the driver
>>> code whenever we want to add support for a new SMMU implementation. If
>>> we do this all in the DT, as Thor is trying to do, then older kernels
>>> will work well with new hardware.
>>>
>>>> Hi Will,
>>>> Am I unable to understand the intentions here for Thor's clock-fetch
>>>> design change?
>>> I'm having trouble parsing your question, sorry. Please work with Thor
>>> so that we have a single way to get the clock information. My 
>>> preference
>>> is to take it from the firmware, for the reason I stated above.
>> Hi Will,
>>
>> Sure, thanks. I will work with Thor to get this going.
>>
>> Hi Thor,
>> Does it sound okay to you to squash your patch [1] into my patch [2] 
>> with
>> your 'Signed-off-by' tag?
>> I will update the commit log to include the information about getting
>> clock details from device tree.
>>
>> [1] https://patchwork.kernel.org/patch/10628725/
>> [2] https://patchwork.kernel.org/patch/10686061/
>>
>
> Yes, that would be great and easier to understand than my patch on top 
> of yours.
>
> Additionally, can you remove the "Error:" as Will requested as part of 
> the squash?

Thanks for your consent. I have reworked the patch today, and have 
addressed Will's
comment. I will give a try on the board and post it by tomorrow.

Best regards
Vivek

>
> Thank you!
>
> Thor
>
>> Best regards
>> Vivek
>>>
>>> Will
>>
>>
>