[Intel-gfx] [PATCH v2 1/3] drm/i915: Fix up CNL cdclk related limits

[Rodrigo Vivi]

cool, with

v2 of patch 1
v2 of patch 2
patch 3

display works properly here on cnl.

On Mon, Jul 10, 2017 at 6:02 AM,  <ville.syrjala at linux.intel.com> wrote:
> From: Ville Syrjälä <ville.syrjala at linux.intel.com>
>
> Follow the GLK path when computing cdclk and related limits. CNL
> pipes also produce two pixels per clock, so that's what we should
> really use. However for the purposes of pixel rate calculations we
> will assume one pixel per clock to keep the voltage higher, at least
> until the missing voltage scaling for DDI clocks is implemented.
>
> For the HBR2 vs. audio issue the limit should more correctly be 336
> MHz, but the GLK limit of 316.8 MHz works just as well and results
> in picking at least 336 MHz. Also toss in some related w/a numbers.
>
> v2: Assume 1 pixel per clock for the purposes of max pixel rate
>     calculation until DDI clock voltage scaling is handled
>
> Cc: Paulo Zanoni <paulo.r.zanoni at intel.com>
> Cc: Rodrigo Vivi <rodrigo.vivi at intel.com>
> Cc: Dhinakaran Pandiyan <dhinakaran.pandiyan at intel.com>
> Cc: Maarten Lankhorst <maarten.lankhorst at linux.intel.com>
> Signed-off-by: Ville Syrjälä <ville.syrjala at linux.intel.com>
> ---
>  drivers/gpu/drm/i915/intel_cdclk.c | 20 ++++++++++++++------
>  1 file changed, 14 insertions(+), 6 deletions(-)
>
> diff --git a/drivers/gpu/drm/i915/intel_cdclk.c b/drivers/gpu/drm/i915/intel_cdclk.c
> index 1241e5891b29..4b8eb6a7d852 100644
> --- a/drivers/gpu/drm/i915/intel_cdclk.c
> +++ b/drivers/gpu/drm/i915/intel_cdclk.c
> @@ -1752,12 +1752,13 @@ static int bdw_adjust_min_pipe_pixel_rate(struct intel_crtc_state *crtc_state,
>             crtc_state->has_audio &&
>             crtc_state->port_clock >= 540000 &&
>             crtc_state->lane_count == 4) {
> -               if (IS_CANNONLAKE(dev_priv))
> -                       pixel_rate = max(316800, pixel_rate);
> -               else if (IS_GEMINILAKE(dev_priv))
> +               if (IS_CANNONLAKE(dev_priv) || IS_GEMINILAKE(dev_priv)) {
> +                       /* Display WA #1145: glk,cnl */
>                         pixel_rate = max(2 * 316800, pixel_rate);
> -               else
> +               } else if (IS_GEN9(dev_priv) || IS_BROADWELL(dev_priv)) {
> +                       /* Display WA #1144: skl,bxt */
>                         pixel_rate = max(432000, pixel_rate);
> +               }
>         }
>
>         /* According to BSpec, "The CD clock frequency must be at least twice
> @@ -1766,7 +1767,7 @@ static int bdw_adjust_min_pipe_pixel_rate(struct intel_crtc_state *crtc_state,
>          * two pixels per clock.
>          */
>         if (crtc_state->has_audio && INTEL_GEN(dev_priv) >= 9) {
> -               if (IS_GEMINILAKE(dev_priv))
> +               if (IS_CANNONLAKE(dev_priv) || IS_GEMINILAKE(dev_priv))
>                         pixel_rate = max(2 * 2 * 96000, pixel_rate);
>                 else
>                         pixel_rate = max(2 * 96000, pixel_rate);
> @@ -1999,7 +2000,14 @@ static int intel_compute_max_dotclk(struct drm_i915_private *dev_priv)
>  {
>         int max_cdclk_freq = dev_priv->max_cdclk_freq;
>
> -       if (IS_GEMINILAKE(dev_priv))
> +       if (INTEL_GEN(dev_priv) >= 10)
> +               /*
> +                * FIXME: Allow '2 * max_cdclk_freq'
> +                * once DDI clock voltage requirements are
> +                * handled correctly.
> +                */
> +               return max_cdclk_freq;
> +       else if (IS_GEMINILAKE(dev_priv))
>                 /*
>                  * FIXME: Limiting to 99% as a temporary workaround. See
>                  * glk_calc_cdclk() for details.

Are you sure we don't want this workaround also? With so similar
display engines I wonder if we would end with similar issues.
But I'm just asking... because honestly I didn't check that 99%
workaround closely enough yet...

The rest of the patch makes sense for me and works so feel free to use:

Reviewed-by: Rodrigo Vivi <rodrigo.vivi at intel.com>
Tested-by: Rodrigo Vivi <rodrigo.vivi at intel.com>

rv-b only for this test for now, but tested-by you could use in all 3
patches mentioned above...


> --
> 2.13.0
>
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-- 
Rodrigo Vivi
Blog: http://blog.vivi.eng.br