Re: [PATCH 1/2] ASoC: Intel: sst: Fallback to BYT-CR if IRQ 5 is missing

Stephan Gerhold
2019-01-01T21:11:30Z

On Mon, Dec 31, 2018 at 02:44:58PM -0600, Pierre-Louis Bossart wrote:
>
> On 12/31/18 10:30 AM, Stephan Gerhold wrote:
> > On Mon, Dec 31, 2018 at 09:38:21AM -0600, Pierre-Louis Bossart wrote:
> > > On 12/22/18 8:47 AM, Stephan Gerhold wrote:
> > > > Some devices detected as BYT-T by the PMIC-type based detection
> > > > have only a single IRQ listed in the 80860F28 ACPI device. This
> > > > causes -ENXIO later when attempting to get the IRQ at index 5.
> > > > It turns out these devices behave more like BYT-CR devices,
> > > > and using the IRQ at index 0 makes sound work correctly.
> > > >
> > > > This patch adds a fallback for these devices to is_byt_cr():
> > > > If there is no IRQ resource at index 5, treating the device
> > > > as BYT-T is guaranteed to fail later, so we can safely treat
> > > > these devices as BYT-CR without breaking any working device.
> > > >
> > > > Link: http://mailman.alsa-project.org/pipermail/alsa-devel/2018-December/143176.html
> > > > Signed-off-by: Stephan Gerhold <stephan@gerhold.net>
> > > > ---
> > > > Moved the "Detected Baytrail-CR platform" message to is_byt_cr()
> > > > so we can log a different message if the fallback is used.
> > > >
> > > > Tested this on my device as-is, and simulated a "normal"
> > > > BYT-T and BYT-CR device (copied their IRQs to a custom DSDT).
> > > >
> > > > sound/soc/intel/atom/sst/sst_acpi.c | 24 ++++++++++++++++++------
> > > > 1 file changed, 18 insertions(+), 6 deletions(-)
> > > >
> > > > diff --git a/sound/soc/intel/atom/sst/sst_acpi.c b/sound/soc/intel/atom/sst/sst_acpi.c
> > > > index 3a95ebbfc45d..755a396121ff 100644
> > > > --- a/sound/soc/intel/atom/sst/sst_acpi.c
> > > > +++ b/sound/soc/intel/atom/sst/sst_acpi.c
> > > > @@ -255,10 +255,22 @@ static int is_byt(void)
> > > > return status;
> > > > }
> > > > -static int is_byt_cr(struct device *dev, bool *bytcr)
> > > > +static int is_byt_cr(struct platform_device *pdev, bool *bytcr)
> > > > {
> > > > + struct device *dev = &pdev->dev;
> > > > int status = 0;
> > > > + if (platform_get_resource(pdev, IORESOURCE_IRQ, 5) == NULL) {
> > > > + /*
> > > > + * Some devices detected as BYT-T have only a single IRQ listed,
> > > > + * causing platform_get_irq with index 5 to return -ENXIO.
> > > > + * The correct IRQ in this case is at index 0, as used on BYT-CR.
> > > > + */
> > > > + dev_info(dev, "Falling back to Baytrail-CR platform\n");
> > > > + *bytcr = true;
> > > > + return status;
> > > > + }
> > > > +
> > > Isn't this going to bypass the PMIC-based detection on all BYT-CR devices?
> > > Maybe move this code as a fallback used when the PMIC-based detection isn't
> > > positive?
> > >
> > Except for the message that is logged, it does not really make a
> > difference. PMIC-based detection is still used for most BYT-CR devices,
> > which usually have 6 IRQs listed. For the few that have not, the end
> > result (bytcr = true) is the same, even if they now use the fallback.
> >
> > I mentioned this in a previous mail when I asked you which option you
> > would prefer (see [1]). Since is_byt_cr() has multiple returns,
> > I cannot just put it last without refactoring the entire method.
> > (Which is something I wanted to avoid...)
>
> Ah yes, but there was a side thread with Andy Shevchenko where we discussed
> that the initial return can be simplified since there are wrappers for
> iosf_mbi_available even when CONFIG_IOSF_MBI is not enabled. The code could
> be something like
>
> diff --git a/sound/soc/intel/atom/sst/sst_acpi.c
> b/sound/soc/intel/atom/sst/sst_acpi.c
> index ac542535b9d5..58e389a64c6a 100644
> --- a/sound/soc/intel/atom/sst/sst_acpi.c
> +++ b/sound/soc/intel/atom/sst/sst_acpi.c
> @@ -255,17 +255,16 @@ static int is_byt(void)
>         return status;
>  }
>
> -static int is_byt_cr(struct device *dev, bool *bytcr)
> +static int is_byt_cr(struct platform_device *pdev, bool *bytcr)
>  {
> +       struct device *dev = &pdev->dev;
> +       u32 bios_status;
>         int status = 0;
>
> -       if (IS_ENABLED(CONFIG_IOSF_MBI)) {
> -               u32 bios_status;
> +       if (!is_byt())
> +               return status;
>
> -               if (!is_byt() || !iosf_mbi_available()) {
> -                       /* bail silently */
> -                       return status;
> -               }
> +       if (iosf_mbi_available()) {
>
>                 status = iosf_mbi_read(BT_MBI_UNIT_PMC, /* 0x04 PUNIT */
>                                        MBI_REG_READ, /* 0x10 */
> @@ -286,6 +285,20 @@ static int is_byt_cr(struct device *dev, bool *bytcr)
>         } else {
>                 dev_info(dev, "IOSF_MBI not enabled, no BYT-CR
> detection\n");
>         }
> +
> +       if (*bytcr == false &&
> +           platform_get_resource(pdev, IORESOURCE_IRQ, 5) == NULL) {
> +               /*
> +                * Some devices detected as BYT-T have only a single IRQ
> listed,
> +                * causing platform_get_irq with index 5 to return -ENXIO.
> +                * The correct IRQ in this case is at index 0, as used on
> +                * BYT-CR.
> +                */
> +               dev_info(dev, "Falling back to Baytrail-CR platform\n");
> +               status = 0;
> +               *bytcr = true;
> +       }
> +
>         return status;
>  }
>
>

Thanks! That looks fine to me. I will test it on my device and send a v2
shortly.

Speaking of simplifying is_byt_cr(): Especially its usage in

ret = is_byt_cr(pdev, &bytcr);
if (!(ret < 0 || !bytcr)) {
/* override resource info */
byt_rvp_platform_data.res_info = &bytcr_res_info;
}

with the negated "or" has been rather confusing to read for me.
In my opinion, it would be easier to understand as:
if (ret == 0 && bytcr)

The return value (`ret`) is only used in this if statement.
Since `bytcr` stays false when an error occurs in is_byt_cr(),
we could further simplify this by returning the bool directly:
if (is_byt_cr(pdev))

Together with:

static bool is_byt_cr(struct platform_device *pdev)
{
struct device *dev = &pdev->dev;

if (!is_byt())
return false;

if (iosf_mbi_available()) {
u32 bios_status;
int status = iosf_mbi_read(BT_MBI_UNIT_PMC, /* 0x04 PUNIT */
MBI_REG_READ, /* 0x10 */
0x006, /* BIOS_CONFIG */
&bios_status);

if (status) {
dev_err(dev, "could not read PUNIT BIOS_CONFIG\n");
} else {
/* bits 26:27 mirror PMIC options */
bios_status = (bios_status >> 26) & 3;

if ((bios_status == 1) || (bios_status == 3)) {
dev_info(dev, "Detected Baytrail-CR platform\n");
return true;
} else {
dev_info(dev, "BYT-CR not detected\n");
}
}
} else {
dev_info(dev, "IOSF_MBI not enabled, no BYT-CR detection\n");
}

if (platform_get_resource(pdev, IORESOURCE_IRQ, 5) == NULL) {
/*
* Some devices detected as BYT-T have only a single IRQ listed,
* causing platform_get_irq with index 5 to return -ENXIO.
* The correct IRQ in this case is at index 0, as used on BYT-CR.
*/
dev_info(dev, "Falling back to Baytrail-CR platform\n");
return true;
}

return false;
}

What do you think?

>
>
> >
> > [1]: http://mailman.alsa-project.org/pipermail/alsa-devel/2018-December/143339.html
> >
> > > > if (IS_ENABLED(CONFIG_IOSF_MBI)) {
> > > > u32 bios_status;
> > > > @@ -278,10 +290,12 @@ static int is_byt_cr(struct device *dev, bool *bytcr)
> > > > /* bits 26:27 mirror PMIC options */
> > > > bios_status = (bios_status >> 26) & 3;
> > > > - if ((bios_status == 1) || (bios_status == 3))
> > > > + if ((bios_status == 1) || (bios_status == 3)) {
> > > > + dev_info(dev, "Detected Baytrail-CR platform\n");
> > > > *bytcr = true;
> > > > - else
> > > > + } else {
> > > > dev_info(dev, "BYT-CR not detected\n");
> > > > + }
> > > > }
> > > > } else {
> > > > dev_info(dev, "IOSF_MBI not enabled, no BYT-CR detection\n");
> > > > @@ -333,10 +347,8 @@ static int sst_acpi_probe(struct platform_device *pdev)
> > > > if (ret < 0)
> > > > return ret;
> > > > - ret = is_byt_cr(dev, &bytcr);
> > > > + ret = is_byt_cr(pdev, &bytcr);
> > > > if (!(ret < 0 || !bytcr)) {
> > > > - dev_info(dev, "Detected Baytrail-CR platform\n");
> > > > -
> > > > /* override resource info */
> > > > byt_rvp_platform_data.res_info = &bytcr_res_info;
> > > > }
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