linux-kernel - Re: [GIT PULL] sound updates for 4.21

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Date:   Mon, 31 Dec 2018 09:22:02 -0600
From:   Pierre-Louis Bossart <pierre-louis.bossart@...ux.intel.com>
To:     Azat Khuzhin <dohardgopro@...il.com>, Takashi Iwai <tiwai@...e.de>
Cc:     Linus Torvalds <torvalds@...ux-foundation.org>,
        Ingo Molnar <mingo@...nel.org>,
        Mark Brown <broonie@...nel.org>,
        Liam Girdwood <lgirdwood@...il.com>,
        Linux Kernel Mailing List <linux-kernel@...r.kernel.org>
Subject: Re: [GIT PULL] sound updates for 4.21


On 12/31/18 7:43 AM, Azat Khuzhin wrote:
>> +/* CFL and later models, preferring ASoC when DSP is available */
>> +#define IS_CFL_PLUS(pci)            \
>> +       ((pci)->vendor == 0x8086 &&  \
>> +        ((pci)->device == 0xa348 || \
>> +         (pci)->device == 0x9dc8 || \
>> +         (pci)->device == 0x34c8))
>> +
>>   static char *driver_short_names[] = {
>>          [AZX_DRIVER_ICH] = "HDA Intel",
>>          [AZX_DRIVER_PCH] = "HDA Intel PCH",
>> @@ -2056,7 +2063,7 @@ static int azx_probe(struct pci_dev *pci,
>>          if (pci_id->driver_data & AZX_DCAPS_INTEL_SHARED) {
>>                  switch (skl_pci_binding) {
>>                  case SND_SKL_PCI_BIND_AUTO:
>> -                       if (pci->class != 0x040300) {
>> +                       if (pci->class != 0x040300 && IS_CFL_PLUS(pci)) {
>>                                  dev_info(&pci->dev, "The DSP is enabled on this platform, aborting probe\n");
>>                                  return -ENODEV;
>>                          }
> lenovo thinkpad carbon 6th gen - no sound after this patch, and this
> patch should fix sound issue for it (not tested, just checking the
> condition and pci attrs)
> But what interesting is that I cannot remove snd_soc_skl module
> without reboot (to adjust "pci_binding=1" so make sound works),
> because kernel hang after short period doing it:
>
> # rmmod snd_soc_skl_ssp_clk
> # rmmod snd_soc_skl
>
> WARN_ON triggered on rmmod:

This is unfortunately a known issue with this driver, Takashi and I had 
a couple of email threads on this. Even without errors removing the 
module doesn't seem to release all resources. I don't like this at all, 
and for the Sound Open Firmware (SOF) driver I mandated module 
load-unload as a functional requirement along with zero warnings w/ 
Sparse, Coccinelle and friends, but on this legacy code I am afraid 
there is no simple fix - at least not in a merge window or a single 
kernel cycle.