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

Stephan Gerhold
2018-12-31T16:30:29Z

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...)

[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;
> > }