Re: [PATCH 2/7] drm/i915: Add get_eld audio component

From: Takashi Iwai <tiwai@suse.de>
To: "Ville Syrjälä" <ville.syrjala@linux.intel.com>
Cc: alsa-devel@alsa-project.org,
	Mengdong Lin <mengdong.lin@linux.intel.com>,
	Vinod Koul <vinod.koul@intel.com>,
	intel-gfx@lists.freedesktop.org,
	Daniel Vetter <daniel.vetter@intel.com>,
	David Henningsson <david.henningsson@canonical.com>
Subject: Re: [PATCH 2/7] drm/i915: Add get_eld audio component
Date: Mon, 30 Nov 2015 16:29:57 +0100	[thread overview]
Message-ID: <s5hlh9fy07e.wl-tiwai@suse.de> (raw)
In-Reply-To: <20151130152441.GS4437@intel.com>

On Mon, 30 Nov 2015 16:24:41 +0100,
Ville Syrjälä wrote:
> 
> On Mon, Nov 30, 2015 at 02:37:46PM +0100, Takashi Iwai wrote:
> > Implement a new i915_audio_component_ops, get_eld().  It's called by
> > the audio driver to fetch the current ELD of the given HDMI/DP port.
> > It returns the size of ELD bytes if it's valid, or zero if the audio
> > is disabled or unplugged, or a negative error code.
> 
> Why do we need this? Isn't it something the eld notify hook should
> pass from i915 to the audio driver?

We need this at least in two situations:
- when the audio driver is probed
- when the audio driver is resumed

> At least with the locking you have for this, the audio driver can not
> call this from the eld notify hook since it would deadlock.

OK, then we may change the eld_notify to pass the values in the
arguments, and also add the new op with a lock to be called from other
places from other places.

Takashi
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