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

[Stephan Gerhold]

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 at 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;
> >   	}