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

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Date:   Fri, 18 Jun 2021 12:41:09 +0100
From:   Srinivas Kandagatla <srinivas.kandagatla@...aro.org>
To:     Marek Szyprowski <m.szyprowski@...sung.com>,
        Srinivasa Rao Mandadapu <srivasam@...eaurora.org>,
        agross@...nel.org, bjorn.andersson@...aro.org, lgirdwood@...il.com,
        broonie@...nel.org, robh+dt@...nel.org, plai@...eaurora.org,
        bgoswami@...eaurora.org, perex@...ex.cz, tiwai@...e.com,
        rohitkr@...eaurora.org, linux-arm-msm@...r.kernel.org,
        alsa-devel@...a-project.org, devicetree@...r.kernel.org,
        linux-kernel@...r.kernel.org, swboyd@...omium.org,
        judyhsiao@...omium.org
Subject: Re: [PATCH v3] ASoC: qcom: Fix for DMA interrupt clear reg
 overwriting

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@...eaurora.org>
> 
> 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
>