Messages in this thread | | | Subject | Re: [alsa-devel] [RFC PATCH 2/2] ASoC: samsung: Print a one-time message if the snow driver's probe defers | From | Javier Martinez Canillas <> | Date | Thu, 20 Oct 2016 07:41:57 -0300 |
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Hello Sylwester,
Thanks a lot for your feedback.
On 10/20/2016 06:12 AM, Sylwester Nawrocki wrote: > On 10/19/2016 07:21 PM, Javier Martinez Canillas wrote: >> If the snd_soc_register_card() fails due a missing resource and the probe >> has to be deferred, the driver prints an error message. >> >> But since many probe retries can happen before a resource is available, >> the printed messages can spam the kernel log buffer and slow the boot. > > Do you know why CPU DAI is not registered by the time snow machine > driver gets probed? Did you try to debug the I2S driver? Does perhaps > deferring happen due to some I2S clocks missing? DMA seems to be > already initialized. > The deferral loop looks suspicious, do you perhaps know what commits
It's suspicious indeed and I've been trying to figure out what changed the behavior in v4.8 but I haven't found it yet.
> in v4.8 cause such changes in probing order? Did you start to use
I did a git bisect to find the first v4.8 commit that caused this but finished in a merge commit c9b95e5961c0 ("Merge tag 'sound-4.8-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/tiwai/sound").
That branch alone works the same than v4.7 so it seems that is not a single commit but a combination from different branches that caused this on integration.
> some drivers as loadable module? >
I see no relevant changes in exynos_defconfig between v4.7..v4.8 and also no changes in drivers/Makefile that could cause things to be initialized on a different order.
But I thought the patches had merits on its own since probe deferral can make a driver probe many times and the error logs were noisy. I wasn't sure though and that's why are marked as RFC.
> As far as the error log is concerned, I would just not print anything > in snow_probe() when register_card() returns EPROBE_DEFER. >
I believe it may be useful to know that a driver's probe is deferring due a missing dependency but have no strong opinion and can remove the message.
Best regards, -- Javier Martinez Canillas Open Source Group Samsung Research America
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