[Intel-gfx] [PATCH 5/6] drm/i915: don't write PLANE_BUF_CFG twice every time

[Matt Roper]

On Thu, Oct 04, 2018 at 04:15:59PM -0700, Paulo Zanoni wrote:
> We were writing to PLANE_BUF_CFG(pipe, plane_id) twice for every
> platform, and we were even using different values on the gen10- planar
> case. The first write is useless since it just gets replaced with the
> next one, so kill it.
> 
> There's a lot to improve in the DDB code, but let's start by avoiding
> the double write.
> 
> Signed-off-by: Paulo Zanoni <paulo.r.zanoni at intel.com>

Looks like leftover code that was intended for removal in commit
b879d58ff31ba ("drm/i915/skl+: refactor WM calculation for NV12").

Reviewed-by: Matt Roper <matthew.d.roper at intel.com>

One other comment below.

> ---
>  drivers/gpu/drm/i915/intel_pm.c | 2 --
>  1 file changed, 2 deletions(-)
> 
> diff --git a/drivers/gpu/drm/i915/intel_pm.c b/drivers/gpu/drm/i915/intel_pm.c
> index 14f13a371989..53b4a9a2de69 100644
> --- a/drivers/gpu/drm/i915/intel_pm.c
> +++ b/drivers/gpu/drm/i915/intel_pm.c
> @@ -5040,8 +5040,6 @@ static void skl_write_plane_wm(struct intel_crtc *intel_crtc,
>  	skl_write_wm_level(dev_priv, PLANE_WM_TRANS(pipe, plane_id),
>  			   &wm->trans_wm);
>  
> -	skl_ddb_entry_write(dev_priv, PLANE_BUF_CFG(pipe, plane_id),
> -			    &ddb->plane[pipe][plane_id]);
>  	/* FIXME: add proper NV12 support for ICL. */
>  	if (INTEL_GEN(dev_priv) >= 11)
>  		return skl_ddb_entry_write(dev_priv,

Neither this function nor skl_ddb_entry_write() have return values, so
I'm surprised this doesn't raise a compiler warning.  Maybe while we're
touching this area of the code we should drop the 'return' here and
convert the next 'if' to an 'else if.'


Matt

> -- 
> 2.14.4
> 
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-- 
Matt Roper
Graphics Software Engineer
IoTG Platform Enabling & Development
Intel Corporation
(916) 356-2795