Re: [PATCH] ALSA: hda: Enable sync-write operation as default for all controllers

[Jon Hunter <jonathanh-DDmLM1+adcrQT0dZR+AlfA@public.gmane.org>]

On 14/07/2020 09:30, Takashi Iwai wrote:
> On Tue, 14 Jul 2020 10:08:02 +0200,
> Jon Hunter wrote:
>>
>> Hi Takashi,
>>
>> On 18/06/2020 15:40, Takashi Iwai wrote:
>>> In the end we already enabled the sync-write mode for most of HD-audio
>>> controllers including Intel, and it's no big merit to keep the async
>>> write mode for the rest.  Let's make it as default and drop the
>>> superfluous AZX_DCAPS_SYNC_WRITE bit flag.
>>>
>>> Also, avoid to set the allow_bus_reset flag, which is a quite unstable
>>> and hackish behavior that was needed only for some early platforms
>>> (decades ago).  The straight fallback to the single cmd mode is more
>>> robust.
>>>
>>> Signed-off-by: Takashi Iwai <tiwai-l3A5Bk7waGM@public.gmane.org>
>>
>>
>> I have noticed a regression in HDA playback on our Tegra186 Jetson TX2
>> platform. Bisect is pointing to this patch and reverting this does
>> appear to fix it. Interestingly, I am not seeing any problems on other
>> Tegra platforms, however, Tegra186 does have the IOMMU enabled for HDA
>> which is one different between the other platforms.
>>
>> We can take a closer look at this for Tegra, but I am wondering if we
>> revert this for Tegra for now.
> 
> It's a deja vu, we (or someone else in Nvidia?) discussed it in the
> past?
> 
> The patch below should cure the problem temporarily, as it sets the
> polling mode as default for Tegra.  But it'd be appreciated if you can
> find the root cause.
> 
> 
> thanks,
> 
> Takashi
> 
> --- a/sound/pci/hda/hda_tegra.c
> +++ b/sound/pci/hda/hda_tegra.c
> @@ -394,6 +394,7 @@ static int hda_tegra_create(struct snd_card *card,
>  	if (err < 0)
>  		return err;
>  
> +	chip->bus.core.polling = 1;
>  	chip->bus.core.needs_damn_long_delay = 1;
>  
>  	err = snd_device_new(card, SNDRV_DEV_LOWLEVEL, chip, &ops);
> 

Did you mean ...

diff --git a/sound/pci/hda/hda_tegra.c b/sound/pci/hda/hda_tegra.c
index 0cc5fad1af8a..5637f0129932 100644
--- a/sound/pci/hda/hda_tegra.c
+++ b/sound/pci/hda/hda_tegra.c
@@ -443,6 +443,7 @@ static int hda_tegra_create(struct snd_card *card,
        if (err < 0)
                return err;

+       chip->bus.core.sync_write = 0;
        chip->bus.core.needs_damn_long_delay = 1;
        chip->bus.core.aligned_mmio = 1;

The above works for me.

Cheers
Jon

-- 
nvpublic