diff mbox

drm/radeon: apply more strict limits for PLL params v2

Message ID 1397229865-2836-1-git-send-email-deathsimple@vodafone.de (mailing list archive)
State New, archived
Headers show

Commit Message

Christian König April 11, 2014, 3:24 p.m. UTC 
From: Christian König <christian.koenig@amd.com>

Letting post and refernce divider get to big is bad for signal stability.

v2: increase the limit to 210

Signed-off-by: Christian König <christian.koenig@amd.com>
---
 drivers/gpu/drm/radeon/radeon_display.c | 3 +++
 1 file changed, 3 insertions(+)

Comments

Alex Deucher April 11, 2014, 3:33 p.m. UTC | #1 
On Fri, Apr 11, 2014 at 11:24 AM, Christian König
<deathsimple@vodafone.de> wrote:
> From: Christian König <christian.koenig@amd.com>
>
> Letting post and refernce divider get to big is bad for signal stability.
>
> v2: increase the limit to 210

Maybe mention the bug number?

>
> Signed-off-by: Christian König <christian.koenig@amd.com>

Reviewed-by: Alex Deucher <alexander.deucher@amd.com>

> ---
>  drivers/gpu/drm/radeon/radeon_display.c | 3 +++
>  1 file changed, 3 insertions(+)
>
> diff --git a/drivers/gpu/drm/radeon/radeon_display.c b/drivers/gpu/drm/radeon/radeon_display.c
> index 386cfa4..2f42912 100644
> --- a/drivers/gpu/drm/radeon/radeon_display.c
> +++ b/drivers/gpu/drm/radeon/radeon_display.c
> @@ -937,6 +937,9 @@ void radeon_compute_pll_avivo(struct radeon_pll *pll,
>         }
>         post_div = post_div_best;
>
> +       /* limit reference * post divider to a maximum */
> +       ref_div_max = min(210 / post_div, ref_div_max);
> +
>         /* get matching reference and feedback divider */
>         ref_div = max(den / post_div, 1u);
>         fb_div = nom;
> --
> 1.9.1
>
> _______________________________________________
> dri-devel mailing list
> dri-devel@lists.freedesktop.org
> http://lists.freedesktop.org/mailman/listinfo/dri-devel
diff mbox

Patch

diff --git a/drivers/gpu/drm/radeon/radeon_display.c b/drivers/gpu/drm/radeon/radeon_display.c
index 386cfa4..2f42912 100644
--- a/drivers/gpu/drm/radeon/radeon_display.c
+++ b/drivers/gpu/drm/radeon/radeon_display.c
@@ -937,6 +937,9 @@  void radeon_compute_pll_avivo(struct radeon_pll *pll,
 	}
 	post_div = post_div_best;
 
+	/* limit reference * post divider to a maximum */
+	ref_div_max = min(210 / post_div, ref_div_max);
+
 	/* get matching reference and feedback divider */
 	ref_div = max(den / post_div, 1u);
 	fb_div = nom;