Re: [PATCH v2 0/9] sound: Use -EPROBE_DEFER instead of i915 module loading.
From: Maarten Lankhorst
Date: Mon Jul 31 2023 - 12:38:34 EST
Hey,
Den 2023-07-31 kl. 17:51, skrev Takashi Iwai:
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?
I've been working on a small change to keep the workqueue in SOF and
only move the binding to the probe function to match what snd-hda-intel
is doing, but I don't know if that is needed?
It was a bit unclear to me based on feedback if I should try to kill the
workqueue on all drivers (but with no way to test), or keep it around.
Cheers,
~Maarten