Re: [PATCH v3] ASoC: qcom: Fix for DMA interrupt clear reg overwriting

[Srinivas Kandagatla]

Hi Marek,

Thanks for testing next and reporting this back.

On 17/06/2021 20:35, Marek Szyprowski wrote:
> Hi,
>
> On 09.06.2021 09:23, Srinivasa Rao Mandadapu wrote:
> > The DMA interrupt clear register overwritten during
> > simultaneous playback and capture in lpass platform
> > interrupt handler. It's causing playback or capture stuck
> > in similtaneous plaback on speaker and capture on dmic test.
> > Update appropriate reg fields of corresponding channel instead
> > of entire register write.
> >
> > Fixes: commit c5c8635a04711 ("ASoC: qcom: Add LPASS platform driver")
> >
> > Signed-off-by: Srinivasa Rao Mandadapu <srivasam@xxxxxxxxxxxxxx>
>
> This patch landed recently in linux-next as commit da0363f7bfd3 ("ASoC:
> qcom: Fix for DMA interrupt clear reg overwriting"). It breaks ALSA
> playback on DragonBoard 410c (arch/arm64/boot/dts/qcom/apq8016-sbc.dts).
> After applying this patch, running 'speaker-test -l1' never finishes.
> There is no error nor kernel warning message. Before that commit, the
> playback worked fine on that board.

TBH, I should have looked at the hw register description that is being 
updated in the patch. This is a software write only and hardware 
readable register for which update_bits really does not make sense at 
all. While digging out I found an issue with regmap_cache reads which 
should have reported an error while attempting to even do this. I sent 
out a patch to fix this.

Now for this patch itself, We should send a patch to revert it.


thanks,
srini


> > ---
> > Changes since v2:
> > 	-- Removed redundant variables.
> > Changes since v1:
> > 	-- Subject lines changed.
> >    sound/soc/qcom/lpass-platform.c | 12 ++++++------
> >    1 file changed, 6 insertions(+), 6 deletions(-)
> >
> > diff --git a/sound/soc/qcom/lpass-platform.c b/sound/soc/qcom/lpass-platform.c
> > index 0df9481ea4c6..f9df76d37858 100644
> > --- a/sound/soc/qcom/lpass-platform.c
> > +++ b/sound/soc/qcom/lpass-platform.c
> > @@ -526,7 +526,7 @@ static int lpass_platform_pcmops_trigger(struct snd_soc_component *component,
> >    			return -EINVAL;
> >    		}
> >    
> > -		ret = regmap_write(map, reg_irqclr, val_irqclr);
> > +		ret = regmap_update_bits(map, reg_irqclr, val_irqclr, val_irqclr);
> >    		if (ret) {
> >    			dev_err(soc_runtime->dev, "error writing to irqclear reg: %d\n", ret);
> >    			return ret;
> > @@ -650,10 +650,11 @@ static irqreturn_t lpass_dma_interrupt_handler(
> >    	struct lpass_variant *v = drvdata->variant;
> >    	irqreturn_t ret = IRQ_NONE;
> >    	int rv;
> > -	unsigned int reg = 0, val = 0;
> > +	unsigned int reg, val, mask;
> >    	struct regmap *map;
> >    	unsigned int dai_id = cpu_dai->driver->id;
> >    
> > +	mask = LPAIF_IRQ_ALL(chan);
> >    	switch (dai_id) {
> >    	case LPASS_DP_RX:
> >    		map = drvdata->hdmiif_map;
> > @@ -676,8 +677,7 @@ static irqreturn_t lpass_dma_interrupt_handler(
> >    	return -EINVAL;
> >    	}
> >    	if (interrupts & LPAIF_IRQ_PER(chan)) {
> > -
> > -		rv = regmap_write(map, reg, LPAIF_IRQ_PER(chan) | val);
> > +		rv = regmap_update_bits(map, reg, mask, (LPAIF_IRQ_PER(chan) | val));
> >    		if (rv) {
> >    			dev_err(soc_runtime->dev,
> >    				"error writing to irqclear reg: %d\n", rv);
> > @@ -688,7 +688,7 @@ static irqreturn_t lpass_dma_interrupt_handler(
> >    	}
> >    
> >    	if (interrupts & LPAIF_IRQ_XRUN(chan)) {
> > -		rv = regmap_write(map, reg, LPAIF_IRQ_XRUN(chan) | val);
> > +		rv = regmap_update_bits(map, reg, mask, (LPAIF_IRQ_XRUN(chan) | val));
> >    		if (rv) {
> >    			dev_err(soc_runtime->dev,
> >    				"error writing to irqclear reg: %d\n", rv);
> > @@ -700,7 +700,7 @@ static irqreturn_t lpass_dma_interrupt_handler(
> >    	}
> >    
> >    	if (interrupts & LPAIF_IRQ_ERR(chan)) {
> > -		rv = regmap_write(map, reg, LPAIF_IRQ_ERR(chan) | val);
> > +		rv = regmap_update_bits(map, reg, mask, (LPAIF_IRQ_ERR(chan) | val));
> >    		if (rv) {
> >    			dev_err(soc_runtime->dev,
> >    				"error writing to irqclear reg: %d\n", rv);
>
> Best regards