On Fri, Dec 21, 2018 at 07:14:29PM +0200, Ville Syrjala wrote:
> From: Ville Syrjälä <ville.syrjala@xxxxxxxxxxxxxxx>
>
> I thought we could remove all the early latency==0 checks
> and rely on skl_wm_method{1,2}() checking for it. But
> skl_compute_plane_wm() applies a bunch of workarounds to bump
> up the latency before calling those guys so clearly it won't
> end up doing the right thing. Also not sure if the calculations
> based on the method1/2 results are safe agaisnt overflows so
> it might not work all that well in any case. Let's put the
> early check back.
>
> Signed-off-by: Ville Syrjälä <ville.syrjala@xxxxxxxxxxxxxxx>
Should we remove the tests from skl_wm_method{1,2}() now? I suppose
someone could still use the debugfs interface to set a latency value of
exactly (UINT32_MAX - workaround amount) to make latency wrap around and
hit 0, but I'm not sure if that's really any worse than if they shoot
themselves in the foot by setting a too-low non-zero latency. I don't
think we divide by latency anywhere.
Either way,
Reviewed-by: Matt Roper <matthew.d.roper@xxxxxxxxx>
> ---
> drivers/gpu/drm/i915/intel_pm.c | 3 +++
> 1 file changed, 3 insertions(+)
>
> diff --git a/drivers/gpu/drm/i915/intel_pm.c b/drivers/gpu/drm/i915/intel_pm.c
> index d132ef10fa60..0aac7e7b660f 100644
> --- a/drivers/gpu/drm/i915/intel_pm.c
> +++ b/drivers/gpu/drm/i915/intel_pm.c
> @@ -4701,6 +4701,9 @@ static void skl_compute_plane_wm(const struct intel_crtc_state *cstate,
> to_intel_atomic_state(cstate->base.state);
> bool apply_memory_bw_wa = skl_needs_memory_bw_wa(state);
>
> + if (latency == 0)
> + return;
> +
> /* Display WA #1141: kbl,cfl */
> if ((IS_KABYLAKE(dev_priv) || IS_COFFEELAKE(dev_priv) ||
> IS_CNL_REVID(dev_priv, CNL_REVID_A0, CNL_REVID_B0)) &&
> --
> 2.19.2
>
> _______________________________________________
> Intel-gfx mailing list
> Intel-gfx@xxxxxxxxxxxxxxxxxxxxx
> https://lists.freedesktop.org/mailman/listinfo/intel-gfx
--
Matt Roper
Graphics Software Engineer
IoTG Platform Enabling & Development
Intel Corporation
(916) 356-2795
_______________________________________________
Intel-gfx mailing list
Intel-gfx@xxxxxxxxxxxxxxxxxxxxx
https://lists.freedesktop.org/mailman/listinfo/intel-gfx
