linux-kernel - Re: [PATCH] ALSA: hda: Request driver probe from an async task

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Message-ID: <s5hpo2qru3r.wl-tiwai@suse.de>
Date:   Mon, 23 Apr 2018 14:21:44 +0200
From:   Takashi Iwai <tiwai@...e.de>
To:     "Paul Menzel" <pmenzel+alsa-devel@...gen.mpg.de>
Cc:     "Jaroslav Kysela" <perex@...ex.cz>, <alsa-devel@...a-project.org>,
        <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH] ALSA: hda: Request driver probe from an async task

On Mon, 23 Apr 2018 14:05:52 +0200,
Paul Menzel wrote:
> 
> From: Paul Menzel <pmenzel@...gen.mpg.de>
> Date: Sat, 24 Mar 2018 09:28:43 +0100
> 
> On an ASRock E350M1, with Linux 4.17-rc1 according to `initcall_debug`
> calling `azx_driver_init` takes sometimes more than a few milliseconds,
> and up to 200 ms.
> 
> ```
> [    2.892598] calling  azx_driver_init+0x0/0xfe4 [snd_hda_intel] @ 218
> [    2.943002] initcall azx_driver_init+0x0/0xfe4 [snd_hda_intel]
> returned 0 after 49195 usecs
> ```
> 
> Trying to execute the Linux kernel in less than 500 ms, this is quite a
> hold-up, and therefore request the probe from an async task.
> 
> With this change, the test shows, that the function returns earlier.
> 
> ```
> [    3.254800] calling  azx_driver_init+0x0/0xfe4 [snd_hda_intel] @ 227
> [    3.254887] initcall azx_driver_init+0x0/0xfe4 [snd_hda_intel]
> returned 0 after 66 usecs
> ```
> 
> The same behavior is visible on a Dell OptiPlex 7010. The longer times
> seem to happen, when the module *e1000e* is probed during the same time.
> 
> Signed-off-by: Paul Menzel <pmenzel@...gen.mpg.de>

What actually took so long?  Could you analyze further instead of
blindly putting the flag?


thanks,

Takashi