[05/12] drm/ast: Fix calculation of MCLK

Submitted by Benjamin Herrenschmidt on Feb. 23, 2017, 10:53 p.m.

Details

Message ID 20170223225357.9572-5-benh@kernel.crashing.org
State New
Headers show
Series "Series without cover letter" ( rev: 2 1 ) in DRI devel

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Commit Message

Benjamin Herrenschmidt Feb. 23, 2017, 10:53 p.m.
Some braces were missing causing an incorrect calculation.

Y.C. Chen from Aspeed provided me with the right formula
which I tested on AST2400 and 2500.

The MCLK isn't currently used by the driver (it will eventually
to filter modes) so the issue isn't catastrophic.

Also make the printed value a bit more meaningful

Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
---
 drivers/gpu/drm/ast/ast_main.c | 6 ++++--
 1 file changed, 4 insertions(+), 2 deletions(-)

Patch hide | download patch | download mbox

diff --git a/drivers/gpu/drm/ast/ast_main.c b/drivers/gpu/drm/ast/ast_main.c
index 718c15b..d194af3 100644
--- a/drivers/gpu/drm/ast/ast_main.c
+++ b/drivers/gpu/drm/ast/ast_main.c
@@ -352,7 +352,7 @@  static int ast_get_dram_info(struct drm_device *dev)
 		div = 0x1;
 		break;
 	}
-	ast->mclk = ref_pll * (num + 2) / (denum + 2) * (div * 1000);
+	ast->mclk = ref_pll * (num + 2) / ((denum + 2) * (div * 1000));
 	return 0;
 }
 
@@ -496,7 +496,9 @@  int ast_driver_load(struct drm_device *dev, unsigned long flags)
 		if (ret)
 			goto out_free;
 		ast->vram_size = ast_get_vram_info(dev);
-		DRM_INFO("dram %d %d %d %08x\n", ast->mclk, ast->dram_type, ast->dram_bus_width, ast->vram_size);
+		DRM_INFO("dram MCLK=%u Mhz type=%d bus_width=%d size=%08x\n",
+			 ast->mclk, ast->dram_type,
+			 ast->dram_bus_width, ast->vram_size);
 	}
 
 	if (need_post)

Comments

On Fri, Feb 24, 2017 at 9:23 AM, Benjamin Herrenschmidt
<benh@kernel.crashing.org> wrote:
> Some braces were missing causing an incorrect calculation.
>
> Y.C. Chen from Aspeed provided me with the right formula
> which I tested on AST2400 and 2500.

Y. C. Chen, can you point out this calculation in the programming guide?

All of the PLL calculations I can find in the ast2400 documentation
are different to this one.

Cheers,

Joel

>
> The MCLK isn't currently used by the driver (it will eventually
> to filter modes) so the issue isn't catastrophic.
>
> Also make the printed value a bit more meaningful
>
> Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
> ---
>  drivers/gpu/drm/ast/ast_main.c | 6 ++++--
>  1 file changed, 4 insertions(+), 2 deletions(-)
>
> diff --git a/drivers/gpu/drm/ast/ast_main.c b/drivers/gpu/drm/ast/ast_main.c
> index 718c15b..d194af3 100644
> --- a/drivers/gpu/drm/ast/ast_main.c
> +++ b/drivers/gpu/drm/ast/ast_main.c
> @@ -352,7 +352,7 @@ static int ast_get_dram_info(struct drm_device *dev)
>                 div = 0x1;
>                 break;
>         }
> -       ast->mclk = ref_pll * (num + 2) / (denum + 2) * (div * 1000);
> +       ast->mclk = ref_pll * (num + 2) / ((denum + 2) * (div * 1000));
>         return 0;
>  }
>
> @@ -496,7 +496,9 @@ int ast_driver_load(struct drm_device *dev, unsigned long flags)
>                 if (ret)
>                         goto out_free;
>                 ast->vram_size = ast_get_vram_info(dev);
> -               DRM_INFO("dram %d %d %d %08x\n", ast->mclk, ast->dram_type, ast->dram_bus_width, ast->vram_size);
> +               DRM_INFO("dram MCLK=%u Mhz type=%d bus_width=%d size=%08x\n",
> +                        ast->mclk, ast->dram_type,
> +                        ast->dram_bus_width, ast->vram_size);
>         }
>
>         if (need_post)
> --
> 2.9.3
>
On Fri, 2017-02-24 at 12:54 +1030, Joel Stanley wrote:
> On Fri, Feb 24, 2017 at 9:23 AM, Benjamin Herrenschmidt
> <benh@kernel.crashing.org> wrote:
> > Some braces were missing causing an incorrect calculation.
> > 
> > Y.C. Chen from Aspeed provided me with the right formula
> > which I tested on AST2400 and 2500.
> 
> Y. C. Chen, can you point out this calculation in the programming
> guide?
> 
> All of the PLL calculations I can find in the ast2400 documentation
> are different to this one.

Different PLL register, see my other email. I've checked the result
of the calculation on our AST2500 and AST2400 machines.

Cheers,
Ben.

> Cheers,
> 
> Joel
> 
> > 
> > The MCLK isn't currently used by the driver (it will eventually
> > to filter modes) so the issue isn't catastrophic.
> > 
> > Also make the printed value a bit more meaningful
> > 
> > Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
> > ---
> >  drivers/gpu/drm/ast/ast_main.c | 6 ++++--
> >  1 file changed, 4 insertions(+), 2 deletions(-)
> > 
> > diff --git a/drivers/gpu/drm/ast/ast_main.c
> > b/drivers/gpu/drm/ast/ast_main.c
> > index 718c15b..d194af3 100644
> > --- a/drivers/gpu/drm/ast/ast_main.c
> > +++ b/drivers/gpu/drm/ast/ast_main.c
> > @@ -352,7 +352,7 @@ static int ast_get_dram_info(struct drm_device
> > *dev)
> >                 div = 0x1;
> >                 break;
> >         }
> > -       ast->mclk = ref_pll * (num + 2) / (denum + 2) * (div *
> > 1000);
> > +       ast->mclk = ref_pll * (num + 2) / ((denum + 2) * (div *
> > 1000));
> >         return 0;
> >  }
> > 
> > @@ -496,7 +496,9 @@ int ast_driver_load(struct drm_device *dev,
> > unsigned long flags)
> >                 if (ret)
> >                         goto out_free;
> >                 ast->vram_size = ast_get_vram_info(dev);
> > -               DRM_INFO("dram %d %d %d %08x\n", ast->mclk, ast-
> > >dram_type, ast->dram_bus_width, ast->vram_size);
> > +               DRM_INFO("dram MCLK=%u Mhz type=%d bus_width=%d
> > size=%08x\n",
> > +                        ast->mclk, ast->dram_type,
> > +                        ast->dram_bus_width, ast->vram_size);
> >         }
> > 
> >         if (need_post)
> > --
> > 2.9.3
> >
On Fri, Feb 24, 2017 at 1:08 PM, Benjamin Herrenschmidt
<benh@kernel.crashing.org> wrote:
> On Fri, 2017-02-24 at 12:54 +1030, Joel Stanley wrote:
>> On Fri, Feb 24, 2017 at 9:23 AM, Benjamin Herrenschmidt
>> <benh@kernel.crashing.org> wrote:
>> > Some braces were missing causing an incorrect calculation.
>> >
>> > Y.C. Chen from Aspeed provided me with the right formula
>> > which I tested on AST2400 and 2500.
>>
>> Y. C. Chen, can you point out this calculation in the programming
>> guide?
>>
>> All of the PLL calculations I can find in the ast2400 documentation
>> are different to this one.
>
> Different PLL register, see my other email. I've checked the result
> of the calculation on our AST2500 and AST2400 machines.

I see now. It woudl be good to see the calculation added to Aspeed's
documentation in the future.

Acked-by: Joel Stanley <joel@jms.id.au>

Cheers,

Joel
Tested-by: Y.C. Chen <yc_chen@aspeedtech.com>

-----Original Message-----
From: Benjamin Herrenschmidt [mailto:benh@kernel.crashing.org] 
Sent: Friday, February 24, 2017 6:54 AM
To: dri-devel@lists.freedesktop.org
Cc: YC Chen <yc_chen@aspeedtech.com>; airlied@redhat.com; eich@suse.come; linuxppc-dev@ozlabs.org
Subject: [PATCH 05/12] drm/ast: Fix calculation of MCLK

Some braces were missing causing an incorrect calculation.

Y.C. Chen from Aspeed provided me with the right formula which I tested on AST2400 and 2500.

The MCLK isn't currently used by the driver (it will eventually to filter modes) so the issue isn't catastrophic.

Also make the printed value a bit more meaningful

Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>