linux-kernel - Re: [PATCH 09/19] ASoC: amd: ps: add support for Soundwire DMA interrupts

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Message-ID: <3ec7726d-b70f-df8b-f6b6-8e876b43a570@amd.com>
Date:   Thu, 12 Jan 2023 16:25:00 +0530
From:   "Mukunda,Vijendar" <vijendar.mukunda@....com>
To:     Pierre-Louis Bossart <pierre-louis.bossart@...ux.intel.com>,
        broonie@...nel.org, vkoul@...nel.org, alsa-devel@...a-project.org
Cc:     Basavaraj.Hiregoudar@....com, Sunil-kumar.Dommati@....com,
        Mario.Limonciello@....com, Mastan.Katragadda@....com,
        arungopal.kondaveeti@....com, Liam Girdwood <lgirdwood@...il.com>,
        Jaroslav Kysela <perex@...ex.cz>,
        Takashi Iwai <tiwai@...e.com>,
        Syed Saba Kareem <Syed.SabaKareem@....com>,
        Nathan Chancellor <nathan@...nel.org>,
        open list <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH 09/19] ASoC: amd: ps: add support for Soundwire DMA
 interrupts

On 11/01/23 21:08, Pierre-Louis Bossart wrote:
>
>
>> @@ -167,9 +167,11 @@ struct acp63_dev_data {
>>  	struct platform_device *pdev[ACP63_DEVS];
>>  	struct mutex acp_lock; /* protect shared registers */
>>  	struct fwnode_handle *sdw_fw_node;
>> +	struct work_struct acp_sdw_dma_work;
>>  	u16 pdev_mask;
>>  	u16 pdev_count;
>>  	u16 pdm_dev_index;
>> +	u16 dma_intr_stat[ACP63_SDW_MAX_STREAMS];
> streams and DMAs are different things in SoundWire. You can have a 1:N
> mapping.
>
>>  	u8 sdw_master_count;
>>  	u16 sdw0_dev_index;
>>  	u16 sdw1_dev_index;
>> diff --git a/sound/soc/amd/ps/pci-ps.c b/sound/soc/amd/ps/pci-ps.c
>> index 0fbe5e27f3fb..5b82ee8e3ad8 100644
>> --- a/sound/soc/amd/ps/pci-ps.c
>> +++ b/sound/soc/amd/ps/pci-ps.c
>> @@ -113,14 +113,37 @@ static int acp63_deinit(void __iomem *acp_base, struct device *dev)
>>  	return 0;
>>  }
>>  
>> +static void acp63_sdw_dma_workthread(struct work_struct *work)
>> +{
>> +	struct acp63_dev_data *adata = container_of(work, struct acp63_dev_data,
>> +						    acp_sdw_dma_work);
>> +	struct sdw_dma_dev_data *sdw_dma_data;
>> +	u32 stream_index;
>> +	u16 pdev_index;
>> +
>> +	pdev_index = adata->sdw_dma_dev_index;
>> +	sdw_dma_data = dev_get_drvdata(&adata->pdev[pdev_index]->dev);
>> +
>> +	for (stream_index = 0; stream_index < ACP63_SDW_MAX_STREAMS; stream_index++) {
>> +		if (adata->dma_intr_stat[stream_index]) {
>> +			if (sdw_dma_data->sdw_stream[stream_index])
>> +				snd_pcm_period_elapsed(sdw_dma_data->sdw_stream[stream_index]);
> is there a reason why you do this in a work thread?
>
> IIRC we did this in SOF because of an issue where during an xrun a stop
> IPC would be sent while we were dealing with an IPC.
>
> I don't quite see why it's needed for a DMA?
>
> What am I missing?
Initially, we have used in atomic context. We have seen issues
during stream closure, in interrupt context , handling
period_elapsed causing sleep in atomic context.
To avoid that , we have declared dai_link as non-atomic and
moved period_elapsed code to work queue.
>> +			adata->dma_intr_stat[stream_index] = 0;
>> +		}
>> +	}
>> +}