[Intel-gfx] [PATCH 2/9] drm/i915: Reinstate an early latency==0 check for skl+

[Lisovskiy, Stanislav]

On Fri, 2018-12-21 at 19:14 +0200, Ville Syrjala wrote:
> From: Ville Syrjälä <ville.syrjala at linux.intel.com>
> 
> 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 at linux.intel.com>
> ---
>  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)) &&

Reviewed-by: Stanislav Lisovskiy <stanislav.lisovskiy at intel.com>

-- 
Best Regards,

Lisovskiy Stanislav