linux-kernel - Re: [PATCH 2/2] ALSA: hda/tegra: fix tegra-hda on tegra30 soc

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Date:   Wed, 6 Jan 2021 16:21:41 -0500
From:   Peter Geis <pgwipeout@...il.com>
To:     Sameer Pujar <spujar@...dia.com>
Cc:     Michael Turquette <mturquette@...libre.com>,
        Stephen Boyd <sboyd@...nel.org>,
        Peter De Schrijver <pdeschrijver@...dia.com>,
        Prashant Gaikwad <pgaikwad@...dia.com>,
        Thierry Reding <thierry.reding@...il.com>,
        Jonathan Hunter <jonathanh@...dia.com>,
        Jaroslav Kysela <perex@...ex.cz>,
        Takashi Iwai <tiwai@...e.com>,
        Mohan Kumar <mkumard@...dia.com>, linux-clk@...r.kernel.org,
        linux-tegra@...r.kernel.org, linux-kernel@...r.kernel.org,
        alsa-devel@...a-project.org, Ion Agorria <ion@...rria.com>
Subject: Re: [PATCH 2/2] ALSA: hda/tegra: fix tegra-hda on tegra30 soc

On Tue, Jan 5, 2021 at 1:30 AM Sameer Pujar <spujar@...dia.com> wrote:
>
>
>
> On 12/25/2020 6:50 AM, Peter Geis wrote:
> > External email: Use caution opening links or attachments
> >
> >
> > Currently hda on tegra30 fails to open a stream with an input/output error.
> > This is similar to the issue referenced in [1].
> >
> > For example:
> > speaker-test -Dhw:0,3 -c 2
> >
> > speaker-test 1.2.2
> >
> > Playback device is hw:0,3
> > Stream parameters are 48000Hz, S16_LE, 2 channels
> > Using 16 octaves of pink noise
> > Rate set to 48000Hz (requested 48000Hz)
> > Buffer size range from 64 to 16384
> > Period size range from 32 to 8192
> > Using max buffer size 16384
> > Periods = 4
> > was set period_size = 4096
> > was set buffer_size = 16384
> >   0 - Front Left
> > Write error: -5,Input/output error
> > xrun_recovery failed: -5,Input/output error
> > Transfer failed: Input/output error
> >
> > [1] states "Due to a legacy HW design problem", implying the issue applies to all previous tegra-hda devices.
> > The tegra-hda device was introduced in tegra30 but only utilized in tegra124 until now.
> > For this reason it is unknown when this issue first manifested.
> >
> > Applying the fix in [1] universally resolves this issue on tegra30.
> > Tested on the Ouya game console and the tf201 tablet.
> >
> > [1] 60019d8c650d ("ALSA: hda/tegra: workaround playback failure on Tegra194")
>
> This issue was never seen on Tegra210/Tegra186 and hence at that time it
> was thought to be specific to Tegra194. I never tested this on Tegra30
> since I don't have this device. I will clarify this with HW folks if
> workaround is safer for all chips.

So this is confirmed to not affect Tegra210 and Tegra186, but it does
affect Tegra194 and Tegra30.
Is it possible for the hardware team to pitch on on where the fix was
implemented?

>
> >
> > Signed-off-by: Peter Geis <pgwipeout@...il.com>
> > Tested-by: Ion Agorria <ion@...rria.com>
> > ---
> >   sound/pci/hda/hda_tegra.c | 3 +--
> >   1 file changed, 1 insertion(+), 2 deletions(-)
> >
> > diff --git a/sound/pci/hda/hda_tegra.c b/sound/pci/hda/hda_tegra.c
> > index 70164d1428d4..f8d61e677a09 100644
> > --- a/sound/pci/hda/hda_tegra.c
> > +++ b/sound/pci/hda/hda_tegra.c
> > @@ -388,8 +388,7 @@ static int hda_tegra_first_init(struct azx *chip, struct platform_device *pdev)
> >           * in powers of 2, next available ratio is 16 which can be
> >           * used as a limiting factor here.
> >           */
> > -       if (of_device_is_compatible(np, "nvidia,tegra194-hda"))
> > -               chip->bus.core.sdo_limit = 16;
> > +       chip->bus.core.sdo_limit = 16;
>
> Future Tegra chips address this problem and hence cannot be enforced by
> default. May be we can have like below:
>
> if (of_device_is_compatible(np, "nvidia,tegra30-hda"))
> chip->bus.core.sdo_limit = 16;
>

It will need to be a bit more complicated than that, since the
tegra186 and tegra210 device trees have "nvidia,tegra30-hda" as a
fallback.
Looking at the generation map, tegra30-hda can be the fallback for the
broken implementation and tegra210-hda can be the fallback for the
working implementation.
Does that work for you?

> >
> >          /* codec detection */
> >          if (!bus->codec_mask) {
> > --
> > 2.25.1
> >
>