linux-kernel - Re: [PATCH v2 0/9] sound: Use -EPROBE_DEFER instead of i915 module loading.

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Message-ID: <87r0oohyea.wl-tiwai@suse.de>
Date:   Mon, 31 Jul 2023 17:51:57 +0200
From:   Takashi Iwai <tiwai@...e.de>
To:     Maarten Lankhorst <maarten.lankhorst@...ux.intel.com>
Cc:     alsa-devel@...a-project.org, sound-open-firmware@...a-project.org,
        linux-kernel@...r.kernel.org, Jaroslav Kysela <perex@...ex.cz>,
        Takashi Iwai <tiwai@...e.com>,
        Cezary Rojewski <cezary.rojewski@...el.com>,
        Pierre-Louis Bossart <pierre-louis.bossart@...ux.intel.com>,
        Liam Girdwood <liam.r.girdwood@...ux.intel.com>,
        Peter Ujfalusi <peter.ujfalusi@...ux.intel.com>,
        Bard Liao <yung-chuan.liao@...ux.intel.com>,
        Ranjani Sridharan <ranjani.sridharan@...ux.intel.com>,
        Kai Vehmanen <kai.vehmanen@...ux.intel.com>,
        Mark Brown <broonie@...nel.org>,
        Daniel Baluta <daniel.baluta@....com>
Subject: Re: [PATCH v2 0/9] sound: Use -EPROBE_DEFER instead of i915 module loading.

On Wed, 19 Jul 2023 18:41:32 +0200,
Maarten Lankhorst wrote:
> 
> Explicitly loading i915 becomes a problem when upstreaming the new intel driver
> for Tiger Lake and higher graphics (xe). By loading i915, it doesn't wait for
> driver load of xe, and will fail completely before it loads.
> 
> -EPROBE_DEFER has to be returned before any device is created in probe(),
> otherwise the removal of the device will cause EPROBE_DEFER to try again
> in an infinite loop.
> 
> The conversion is done in gradual steps. First I add an argument to
> snd_hdac_i915_init to allow for -EPROBE_DEFER so I can convert each driver
> separately. Then I convert each driver to move snd_hdac_i915_init out of the
> workqueue. Finally I drop the ability to choose modprobe behavior after the
> last user is converted.
> 
> I suspect the avs and skylake drivers used snd_hdac_i915_init purely for the
> modprobe, but I don't have the hardware to test if it can be safely removed.
> It can still be done easily in a followup patch to simplify probing.
> 
> ---
> New since first version:
> 
> - snd_hda_core.gpu_bind is added as a mechanism to force gpu binding,
>   for testing. snd_hda_core.gpu_bind=0 forces waiting for GPU bind to
>   off, snd_hda_core.gpu_bind=1 forces waiting for gpu bind. Default
>   setting depends on whether kernel booted with nomodeset.
> - Incorporated all feedback review.

Maarten, are you working on v3 patch set?
Or, for moving forward, should we merge v2 now and fix the rest based
on that later?


thanks,

Takashi