Re: [PATCH 6/7] drm/drivers: drop redundant drm_edid_to_eld() calls

From: "Ville Syrjälä" <ville.syrjala@linux.intel.com>
To: Jani Nikula <jani.nikula@intel.com>
Cc: intel-gfx@lists.freedesktop.org,
	"Russell King" <linux@armlinux.org.uk>,
	dri-devel@lists.freedesktop.org,
	"Thierry Reding" <thierry.reding@gmail.com>,
	"Ben Skeggs" <bskeggs@redhat.com>,
	"Alex Deucher" <alexander.deucher@amd.com>,
	"Vincent Abriou" <vincent.abriou@st.com>,
	"Christian König" <christian.koenig@amd.com>
Subject: Re: [PATCH 6/7] drm/drivers: drop redundant drm_edid_to_eld() calls
Date: Wed, 1 Nov 2017 17:05:03 +0200	[thread overview]
Message-ID: <20171101150503.GC10981@intel.com> (raw)
In-Reply-To: <0959ca02b983afc9e74dd9acd190ba6e25f21678.1509545641.git.jani.nikula@intel.com>

On Wed, Nov 01, 2017 at 04:21:02PM +0200, Jani Nikula wrote:
> diff --git a/drivers/gpu/drm/nouveau/nv50_display.c b/drivers/gpu/drm/nouveau/nv50_display.c
> index e4751f92b342..e0a190a0f029 100644
> --- a/drivers/gpu/drm/nouveau/nv50_display.c
> +++ b/drivers/gpu/drm/nouveau/nv50_display.c
> @@ -2688,7 +2688,6 @@ nv50_audio_enable(struct drm_encoder *encoder, struct drm_display_mode *mode)
>  	if (!drm_detect_monitor_audio(nv_connector->edid))
>  		return;
>  
> -	drm_edid_to_eld(&nv_connector->base, nv_connector->edid);
>  	memcpy(args.data, nv_connector->base.eld, sizeof(args.data));
>  
>  	nvif_mthd(disp->disp, 0, &args,

This being the only call outside a .get_modes() hook means this is the
only one that might change some behaviour.

Looks like nv_connector->edid gets updated in .detect() as one might
expect, so in theory we might get a mismatch between the
drm_detect_monitor_audio(edid) check above and the actual eld contents
here if .detect() gets called without .get_modes(). Not a problem for
the probe helper's .fill_modes(), but eg. the poll helper does do that.

I guess we could always consider doing the edid_to_eld() already from
.detect()/.force() for all drivers if we think there would be a good
reason to populate the ELD even if .get_modes()/.fill_modes() hasn't
been called.

-- 
Ville Syrjälä
Intel OTC
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