linux-kernel - Re: [PATCH v2 2/2] drm: sun4i: hdmi: Add support for sun4i HDMI encoder audio

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Date:   Wed, 22 Jan 2020 09:46:17 +0100
From:   Maxime Ripard <mripard@...nel.org>
To:     Mark Brown <broonie@...nel.org>
Cc:     Stefan Mavrodiev <stefan@...mex.com>,
        Dan Williams <dan.j.williams@...el.com>,
        Vinod Koul <vkoul@...nel.org>, Chen-Yu Tsai <wens@...e.org>,
        David Airlie <airlied@...ux.ie>,
        Daniel Vetter <daniel@...ll.ch>,
        open list <linux-kernel@...r.kernel.org>,
        "open list:DMA GENERIC OFFLOAD ENGINE SUBSYSTEM" 
        <dmaengine@...r.kernel.org>,
        "moderated list:ARM/Allwinner sunXi SoC support" 
        <linux-arm-kernel@...ts.infradead.org>,
        "open list:DRM DRIVERS FOR ALLWINNER A10" 
        <dri-devel@...ts.freedesktop.org>, linux-sunxi@...glegroups.com
Subject: Re: [PATCH v2 2/2] drm: sun4i: hdmi: Add support for sun4i HDMI
 encoder audio

On Tue, Jan 21, 2020 at 06:32:47PM +0000, Mark Brown wrote:
> On Tue, Jan 21, 2020 at 07:29:37PM +0100, Maxime Ripard wrote:
>
> > > Mark, our issue here is that we have a driver tied to a device that is
> > > an HDMI encoder. Obviously, we'll want to register into DRM, which is
> > > what we were doing so far, with the usual case where at remove /
> > > unbind time, in order to free the resources, we just retrieve our
> > > pointer to our private structure using the device's drvdata.
>
> > > Now, snd_soc_register_card also sets that pointer to the card we try
> > > to register, which is problematic. It seems that it's used to handle
> > > suspend / resume automatically, which in this case would be also not
> > > really fit for us (or rather, we would need to do more that just
> > > suspend the audio part).
>
> There's a drvdata field in the snd_soc_card for cases like this - would
> that work for you?

Ah, right, we could just retrieve the snd_soc_card in the unbind, and
the retrieve our structure that way. That's pretty simple :)

Stefan, I guess this is the easiest solution, we should just make sure
that there's a comment to explain why we retrieve snd_soc_card in the
unbind, since it's somewhat unusual.

Thanks!
Maxime

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