drm: dw-hdmi: Implement the mode_fixup drm helper

Submitted by Romain Perier on April 7, 2017, 12:17 p.m.

Details

Message ID 20170407121743.4142-1-romain.perier@collabora.com
State New
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Series "drm: dw-hdmi: Implement the mode_fixup drm helper" ( rev: 1 ) in DRI devel

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Commit Message

Romain Perier April 7, 2017, 12:17 p.m.
This helper is supposed to validate or reject the modeline before it
applied by the mode setting. Currently this function has been dropped,
it was previously set to a dummy function that always returned true. For
both cases, this means that userspace can ask for a bad modeline that
will be always accepted.

On some platforms, like Rockchip, the drm dw_hdmi-rockchip variant driver
already implements the atomic_check drm helper, so mode_fixup cannot be
handled and implemented there (as drm_atomic_helper relies on either
atomic_check or mode_fixup).

This commit implements this helper. It only checks that this mode is
correct from the connector point of view

Signed-off-by: Romain Perier <romain.perier@collabora.com>
---
 drivers/gpu/drm/bridge/dw-hdmi.c | 16 ++++++++++++++++
 1 file changed, 16 insertions(+)

Patch hide | download patch | download mbox

diff --git a/drivers/gpu/drm/bridge/dw-hdmi.c b/drivers/gpu/drm/bridge/dw-hdmi.c
index 22211ff..3bd0807 100644
--- a/drivers/gpu/drm/bridge/dw-hdmi.c
+++ b/drivers/gpu/drm/bridge/dw-hdmi.c
@@ -1740,6 +1740,21 @@  static int dw_hdmi_bridge_attach(struct drm_bridge *bridge)
 	return 0;
 }
 
+
+static bool dw_hdmi_bridge_mode_fixup(struct drm_bridge *bridge,
+				      const struct drm_display_mode *orig_mode,
+				      struct drm_display_mode *mode)
+{
+	struct dw_hdmi *hdmi = bridge->driver_private;
+	struct drm_connector *connector = &hdmi->connector;
+	enum drm_mode_status status;
+
+	status = dw_hdmi_connector_mode_valid(connector, mode);
+	if (status != MODE_OK)
+		return false;
+	return true;
+}
+
 static void dw_hdmi_bridge_mode_set(struct drm_bridge *bridge,
 				    struct drm_display_mode *orig_mode,
 				    struct drm_display_mode *mode)
@@ -1781,6 +1796,7 @@  static const struct drm_bridge_funcs dw_hdmi_bridge_funcs = {
 	.enable = dw_hdmi_bridge_enable,
 	.disable = dw_hdmi_bridge_disable,
 	.mode_set = dw_hdmi_bridge_mode_set,
+	.mode_fixup = dw_hdmi_bridge_mode_fixup,
 };
 
 static irqreturn_t dw_hdmi_i2c_irq(struct dw_hdmi *hdmi)

Comments

Hi,

On 4/7/2017 5:47 PM, Romain Perier wrote:
> This helper is supposed to validate or reject the modeline before it
> applied by the mode setting. Currently this function has been dropped,
> it was previously set to a dummy function that always returned true. For
> both cases, this means that userspace can ask for a bad modeline that
> will be always accepted.
>
> On some platforms, like Rockchip, the drm dw_hdmi-rockchip variant driver
> already implements the atomic_check drm helper, so mode_fixup cannot be
> handled and implemented there (as drm_atomic_helper relies on either
> atomic_check or mode_fixup).
>
> This commit implements this helper. It only checks that this mode is
> correct from the connector point of view

We do have a atomic_check op in drm_connector_helper_funcs. I've
rarely seen it being used, but it could be used to validate
the mode w.r.t the connector, rather than checking it in the
bridge's mode_fixup op.

Daniel,

Is it okay to use the connector's atomic_check to validate a mode.
(by peeping into the new_crtc_state->mode?)

Thanks,
Archit

>
> Signed-off-by: Romain Perier <romain.perier@collabora.com>
> ---
>  drivers/gpu/drm/bridge/dw-hdmi.c | 16 ++++++++++++++++
>  1 file changed, 16 insertions(+)
>
> diff --git a/drivers/gpu/drm/bridge/dw-hdmi.c b/drivers/gpu/drm/bridge/dw-hdmi.c
> index 22211ff..3bd0807 100644
> --- a/drivers/gpu/drm/bridge/dw-hdmi.c
> +++ b/drivers/gpu/drm/bridge/dw-hdmi.c
> @@ -1740,6 +1740,21 @@ static int dw_hdmi_bridge_attach(struct drm_bridge *bridge)
>  	return 0;
>  }
>
> +
> +static bool dw_hdmi_bridge_mode_fixup(struct drm_bridge *bridge,
> +				      const struct drm_display_mode *orig_mode,
> +				      struct drm_display_mode *mode)
> +{
> +	struct dw_hdmi *hdmi = bridge->driver_private;
> +	struct drm_connector *connector = &hdmi->connector;
> +	enum drm_mode_status status;
> +
> +	status = dw_hdmi_connector_mode_valid(connector, mode);
> +	if (status != MODE_OK)
> +		return false;
> +	return true;
> +}
> +
>  static void dw_hdmi_bridge_mode_set(struct drm_bridge *bridge,
>  				    struct drm_display_mode *orig_mode,
>  				    struct drm_display_mode *mode)
> @@ -1781,6 +1796,7 @@ static const struct drm_bridge_funcs dw_hdmi_bridge_funcs = {
>  	.enable = dw_hdmi_bridge_enable,
>  	.disable = dw_hdmi_bridge_disable,
>  	.mode_set = dw_hdmi_bridge_mode_set,
> +	.mode_fixup = dw_hdmi_bridge_mode_fixup,
>  };
>
>  static irqreturn_t dw_hdmi_i2c_irq(struct dw_hdmi *hdmi)
>
On Fri, Apr 7, 2017 at 7:15 PM, Archit Taneja <architt@codeaurora.org> wrote:
> On 4/7/2017 5:47 PM, Romain Perier wrote:
>>
>> This helper is supposed to validate or reject the modeline before it
>> applied by the mode setting. Currently this function has been dropped,
>> it was previously set to a dummy function that always returned true. For
>> both cases, this means that userspace can ask for a bad modeline that
>> will be always accepted.
>>
>> On some platforms, like Rockchip, the drm dw_hdmi-rockchip variant driver
>> already implements the atomic_check drm helper, so mode_fixup cannot be
>> handled and implemented there (as drm_atomic_helper relies on either
>> atomic_check or mode_fixup).
>>
>> This commit implements this helper. It only checks that this mode is
>> correct from the connector point of view
>
>
> We do have a atomic_check op in drm_connector_helper_funcs. I've
> rarely seen it being used, but it could be used to validate
> the mode w.r.t the connector, rather than checking it in the
> bridge's mode_fixup op.
>
> Daniel,
>
> Is it okay to use the connector's atomic_check to validate a mode.
> (by peeping into the new_crtc_state->mode?)

This new atomic_check is super-new, and only for validating properties
on the connector, before stuff like the routing or crtc is all set up.
So no, can't be used for that. mode_fixup on the bridge is indeed the
right place for limiting output specific stuff. Yes this is all a bit
awkward, but thus far no one volunteered to improve the helpers after
I explained the full nastiness of the situation ... I think we should
have some helpers that implement the mode_valid helper in terms of the
mode_fixup/atomic_check functions, but that's a bit tricky to get
right :(
-Daniel

>
> Thanks,
> Archit
>
>
>>
>> Signed-off-by: Romain Perier <romain.perier@collabora.com>
>> ---
>>  drivers/gpu/drm/bridge/dw-hdmi.c | 16 ++++++++++++++++
>>  1 file changed, 16 insertions(+)
>>
>> diff --git a/drivers/gpu/drm/bridge/dw-hdmi.c
>> b/drivers/gpu/drm/bridge/dw-hdmi.c
>> index 22211ff..3bd0807 100644
>> --- a/drivers/gpu/drm/bridge/dw-hdmi.c
>> +++ b/drivers/gpu/drm/bridge/dw-hdmi.c
>> @@ -1740,6 +1740,21 @@ static int dw_hdmi_bridge_attach(struct drm_bridge
>> *bridge)
>>         return 0;
>>  }
>>
>> +
>> +static bool dw_hdmi_bridge_mode_fixup(struct drm_bridge *bridge,
>> +                                     const struct drm_display_mode
>> *orig_mode,
>> +                                     struct drm_display_mode *mode)
>> +{
>> +       struct dw_hdmi *hdmi = bridge->driver_private;
>> +       struct drm_connector *connector = &hdmi->connector;
>> +       enum drm_mode_status status;
>> +
>> +       status = dw_hdmi_connector_mode_valid(connector, mode);
>> +       if (status != MODE_OK)
>> +               return false;
>> +       return true;
>> +}
>> +
>>  static void dw_hdmi_bridge_mode_set(struct drm_bridge *bridge,
>>                                     struct drm_display_mode *orig_mode,
>>                                     struct drm_display_mode *mode)
>> @@ -1781,6 +1796,7 @@ static const struct drm_bridge_funcs
>> dw_hdmi_bridge_funcs = {
>>         .enable = dw_hdmi_bridge_enable,
>>         .disable = dw_hdmi_bridge_disable,
>>         .mode_set = dw_hdmi_bridge_mode_set,
>> +       .mode_fixup = dw_hdmi_bridge_mode_fixup,
>>  };
>>
>>  static irqreturn_t dw_hdmi_i2c_irq(struct dw_hdmi *hdmi)
>>
>
> --
> The Qualcomm Innovation Center, Inc. is a member of the Code Aurora Forum,
> hosted by The Linux Foundation
On Fri, Apr 07, 2017 at 02:17:43PM +0200, Romain Perier wrote:
> This helper is supposed to validate or reject the modeline before it
> applied by the mode setting. Currently this function has been dropped,
> it was previously set to a dummy function that always returned true. For
> both cases, this means that userspace can ask for a bad modeline that
> will be always accepted.
> 
> On some platforms, like Rockchip, the drm dw_hdmi-rockchip variant driver
> already implements the atomic_check drm helper, so mode_fixup cannot be
> handled and implemented there (as drm_atomic_helper relies on either
> atomic_check or mode_fixup).
> 
> This commit implements this helper. It only checks that this mode is
> correct from the connector point of view
> 
> Signed-off-by: Romain Perier <romain.perier@collabora.com>

Yup this is how it's supposed to be done, check bridge limits in the
bridge's mode_fixup hook.

Acked-by: Daniel Vetter <daniel.vetter@ffwll.ch>
> ---
>  drivers/gpu/drm/bridge/dw-hdmi.c | 16 ++++++++++++++++
>  1 file changed, 16 insertions(+)
> 
> diff --git a/drivers/gpu/drm/bridge/dw-hdmi.c b/drivers/gpu/drm/bridge/dw-hdmi.c
> index 22211ff..3bd0807 100644
> --- a/drivers/gpu/drm/bridge/dw-hdmi.c
> +++ b/drivers/gpu/drm/bridge/dw-hdmi.c
> @@ -1740,6 +1740,21 @@ static int dw_hdmi_bridge_attach(struct drm_bridge *bridge)
>  	return 0;
>  }
>  
> +
> +static bool dw_hdmi_bridge_mode_fixup(struct drm_bridge *bridge,
> +				      const struct drm_display_mode *orig_mode,
> +				      struct drm_display_mode *mode)
> +{
> +	struct dw_hdmi *hdmi = bridge->driver_private;
> +	struct drm_connector *connector = &hdmi->connector;
> +	enum drm_mode_status status;
> +
> +	status = dw_hdmi_connector_mode_valid(connector, mode);
> +	if (status != MODE_OK)
> +		return false;
> +	return true;
> +}
> +
>  static void dw_hdmi_bridge_mode_set(struct drm_bridge *bridge,
>  				    struct drm_display_mode *orig_mode,
>  				    struct drm_display_mode *mode)
> @@ -1781,6 +1796,7 @@ static const struct drm_bridge_funcs dw_hdmi_bridge_funcs = {
>  	.enable = dw_hdmi_bridge_enable,
>  	.disable = dw_hdmi_bridge_disable,
>  	.mode_set = dw_hdmi_bridge_mode_set,
> +	.mode_fixup = dw_hdmi_bridge_mode_fixup,
>  };
>  
>  static irqreturn_t dw_hdmi_i2c_irq(struct dw_hdmi *hdmi)
> -- 
> 2.9.3
> 
> _______________________________________________
> dri-devel mailing list
> dri-devel@lists.freedesktop.org
> https://lists.freedesktop.org/mailman/listinfo/dri-devel
On 04/08/2017 12:03 AM, Daniel Vetter wrote:
> On Fri, Apr 07, 2017 at 02:17:43PM +0200, Romain Perier wrote:
>> This helper is supposed to validate or reject the modeline before it
>> applied by the mode setting. Currently this function has been dropped,
>> it was previously set to a dummy function that always returned true. For
>> both cases, this means that userspace can ask for a bad modeline that
>> will be always accepted.
>>
>> On some platforms, like Rockchip, the drm dw_hdmi-rockchip variant driver
>> already implements the atomic_check drm helper, so mode_fixup cannot be
>> handled and implemented there (as drm_atomic_helper relies on either
>> atomic_check or mode_fixup).
>>
>> This commit implements this helper. It only checks that this mode is
>> correct from the connector point of view
>>
>> Signed-off-by: Romain Perier <romain.perier@collabora.com>	
>
> Yup this is how it's supposed to be done, check bridge limits in the
> bridge's mode_fixup hook.
>
> Acked-by: Daniel Vetter <daniel.vetter@ffwll.ch>

queued to drm-misc-next-fixes (so that it makes it into 4.12).

Thanks,
Archit

>> ---
>>  drivers/gpu/drm/bridge/dw-hdmi.c | 16 ++++++++++++++++
>>  1 file changed, 16 insertions(+)
>>
>> diff --git a/drivers/gpu/drm/bridge/dw-hdmi.c b/drivers/gpu/drm/bridge/dw-hdmi.c
>> index 22211ff..3bd0807 100644
>> --- a/drivers/gpu/drm/bridge/dw-hdmi.c
>> +++ b/drivers/gpu/drm/bridge/dw-hdmi.c
>> @@ -1740,6 +1740,21 @@ static int dw_hdmi_bridge_attach(struct drm_bridge *bridge)
>>  	return 0;
>>  }
>>
>> +
>> +static bool dw_hdmi_bridge_mode_fixup(struct drm_bridge *bridge,
>> +				      const struct drm_display_mode *orig_mode,
>> +				      struct drm_display_mode *mode)
>> +{
>> +	struct dw_hdmi *hdmi = bridge->driver_private;
>> +	struct drm_connector *connector = &hdmi->connector;
>> +	enum drm_mode_status status;
>> +
>> +	status = dw_hdmi_connector_mode_valid(connector, mode);
>> +	if (status != MODE_OK)
>> +		return false;
>> +	return true;
>> +}
>> +
>>  static void dw_hdmi_bridge_mode_set(struct drm_bridge *bridge,
>>  				    struct drm_display_mode *orig_mode,
>>  				    struct drm_display_mode *mode)
>> @@ -1781,6 +1796,7 @@ static const struct drm_bridge_funcs dw_hdmi_bridge_funcs = {
>>  	.enable = dw_hdmi_bridge_enable,
>>  	.disable = dw_hdmi_bridge_disable,
>>  	.mode_set = dw_hdmi_bridge_mode_set,
>> +	.mode_fixup = dw_hdmi_bridge_mode_fixup,
>>  };
>>
>>  static irqreturn_t dw_hdmi_i2c_irq(struct dw_hdmi *hdmi)
>> --
>> 2.9.3
>>
>> _______________________________________________
>> dri-devel mailing list
>> dri-devel@lists.freedesktop.org
>> https://lists.freedesktop.org/mailman/listinfo/dri-devel
>