linux-kernel - Re: [PATCH v2 2/2] sound: lpass-platform: Move dma channel allocation to pcmops

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Message-ID: <576007FA.2050705@linaro.org>
Date:	Tue, 14 Jun 2016 14:34:50 +0100
From:	Srinivas Kandagatla <srinivas.kandagatla@...aro.org>
To:	Mark Brown <broonie@...nel.org>, alsa-devel@...a-project.org,
	Patrick Lai <plai@...eaurora.org>,
	Banajit Goswami <bgoswami@...eaurora.org>,
	Liam Girdwood <lgirdwood@...il.com>,
	Jaroslav Kysela <perex@...ex.cz>,
	Takashi Iwai <tiwai@...e.com>, linux-kernel@...r.kernel.org
Subject: Re: [PATCH v2 2/2] sound: lpass-platform: Move dma channel allocation
 to pcmops



On 14/06/16 13:49, Kenneth Westfield wrote:
> On Tue, Jun 14, 2016 at 09:30:03AM +0100, Srinivas Kandagatla wrote:
>> Move dma channel allocations to pcmops open and close functions. Reason
>> to do this is that, lpass_platform_pcm_free() accesses snd_soc_pcm_runtime
>> via substream->private data, However By this time runtimes are already
>> freed as part of soc_cleanup_card_resources() sequence.
>>
>> This patch moves the channel allocations/deallocations to pcmops open()
>> and close() respectively, where the code has valid snd_soc_pcm_runtime.
>
>> ---
>>   sound/soc/qcom/lpass-platform.c | 155 +++++++++++++++++++---------------------
>>   1 file changed, 74 insertions(+), 81 deletions(-)
>>
>> diff --git a/sound/soc/qcom/lpass-platform.c b/sound/soc/qcom/lpass-platform.c
>> index db000c6..3bd2cd6 100644
>> --- a/sound/soc/qcom/lpass-platform.c
>> +++ b/sound/soc/qcom/lpass-platform.c
>> @@ -61,7 +61,36 @@ static int lpass_platform_pcmops_open(struct snd_pcm_substream *substream)
>
>> +		if (substream->stream == SNDRV_PCM_STREAM_PLAYBACK) {
>> +			pcm_data->rdma_ch = ch;
>> +			reg =  LPAIF_RDMACTL_REG(v, ch);
>
> Spacing.
Ok, s/  / /
>
>> +		} else {
>> +			pcm_data->wrdma_ch = ch;
>> +			reg =  LPAIF_WRDMACTL_REG(v, ch);
>
> Spacing.
Yep
>
>> +static int lpass_platform_pcmops_close(struct snd_pcm_substream *substream)
>> +{
>> +	struct snd_soc_pcm_runtime *soc_runtime = substream->private_data;
>> +	struct lpass_pcm_data *pcm_data = snd_soc_pcm_get_drvdata(soc_runtime);
>> +	struct lpass_data *drvdata =
>> +		snd_soc_platform_get_drvdata(soc_runtime->platform);
>> +	struct lpass_variant *v = drvdata->variant;
>> +	int ch;
>> +
>> +	if (v->free_dma_channel) {
>> +		if (substream->stream == SNDRV_PCM_STREAM_PLAYBACK)
>> +			ch = pcm_data->rdma_ch;
>> +		else
>> +			ch = pcm_data->wrdma_ch;
>> +
>> +		if (ch >= 0)
>> +			v->free_dma_channel(drvdata, ch);
>> +	}
>
> Since this is being moved from free() to close(), drvdata->substream[ch]
> should be set to NULL.  Otherwise, the array could fill up as the PCM is
> opened/closed.
Yep, we could do that.
>
>> @@ -471,14 +529,12 @@ static int lpass_platform_pcm_new(struct snd_soc_pcm_runtime *soc_runtime)
>>   	struct snd_pcm *pcm = soc_runtime->pcm;
>>   	struct snd_pcm_substream *psubstream, *csubstream;
>>   	struct snd_soc_dai *cpu_dai = soc_runtime->cpu_dai;
>> -	struct lpass_data *drvdata =
>> -		snd_soc_platform_get_drvdata(soc_runtime->platform);
>> -	struct lpass_variant *v = drvdata->variant;
>> -	int ret = -EINVAL;
>> +	struct device *dev = soc_runtime->platform->dev;
>>   	struct lpass_pcm_data *data;
>>   	size_t size = lpass_platform_pcm_hardware.buffer_bytes_max;
>> +	int ret = -EINVAL;
>>
>> -	data = devm_kzalloc(soc_runtime->dev, sizeof(*data), GFP_KERNEL);
>> +	data = devm_kzalloc(dev, sizeof(*data), GFP_KERNEL);
>
> Is the reason for changing the dev pointer similar to why it was changed
> for snd_dma_alloc_pages() below?
Yep, Only reason is that I can fit stuff in single line.
>
>> +		ret = snd_dma_alloc_pages(SNDRV_DMA_TYPE_DEV, dev, size,
>> +					  &psubstream->dma_buffer);
>>   		if (ret) {
>> -			dev_err(soc_runtime->dev,
>> -				"%s() error writing to rdmactl reg: %d\n",
>> -				__func__, ret);
>> -			goto capture_alloc_err;
>> +			dev_err(dev, "can't alloc playback dma buffer\n");
>
> Print the return value.
Ok.
>
>> +		ret = snd_dma_alloc_pages(SNDRV_DMA_TYPE_DEV, dev, size,
>> +					  &csubstream->dma_buffer);
>>   		if (ret) {
>> -			dev_err(soc_runtime->dev,
>> -				"%s() error writing to wrdmactl reg: %d\n",
>> -				__func__, ret);
>> -			goto capture_reg_err;
>> +			dev_err(dev, "can't alloc capture dma buffer\n");
>
> Ditto.
Ok.
>

Thanks,
srini