linux-kernel - Re: [PATCH] dmaengine: add channel device name to channel registration

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Date: Thu, 21 Dec 2023 18:11:33 +0100
From: Amelie Delaunay <amelie.delaunay@...s.st.com>
To: Vinod Koul <vkoul@...nel.org>
CC: Fenghua Yu <fenghua.yu@...el.com>, Dave Jiang <dave.jiang@...el.com>,
        <linux-stm32@...md-mailman.stormreply.com>,
        <dmaengine@...r.kernel.org>, <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH] dmaengine: add channel device name to channel
 registration

Hi Vinod,

On 12/21/23 17:13, Vinod Koul wrote:
> On 13-12-23, 18:40, Amelie Delaunay wrote:
>> Channel device name is used for sysfs, but also by dmatest filter function.
>>
>> With dynamic channel registration, channels can be registered after dma
>> controller registration. Users may want to have specific channel names.
>>
>> If name is NULL, the channel name relies on previous implementation,
>> dma<controller_device_id>chan<channel_device_id>.
> 
> lgtm, where is the user for this..?
> 

I'll send beginning of next year a DMA controller driver for STM32MP25 
SoC family. It relies on the dynamic channel registration. It will be a 
user of this dma_async_device_channel_register(struct dma_device 
*device, struct dma_chan *chan, const char *name).

Regards,
Amelie

>>
>> Signed-off-by: Amelie Delaunay <amelie.delaunay@...s.st.com>
>> ---
>>   drivers/dma/dmaengine.c   | 16 ++++++++++------
>>   drivers/dma/idxd/dma.c    |  2 +-
>>   include/linux/dmaengine.h |  3 ++-
>>   3 files changed, 13 insertions(+), 8 deletions(-)
>>
>> diff --git a/drivers/dma/dmaengine.c b/drivers/dma/dmaengine.c
>> index b7388ae62d7f..7848428da2d6 100644
>> --- a/drivers/dma/dmaengine.c
>> +++ b/drivers/dma/dmaengine.c
>> @@ -1037,7 +1037,8 @@ static int get_dma_id(struct dma_device *device)
>>   }
>>   
>>   static int __dma_async_device_channel_register(struct dma_device *device,
>> -					       struct dma_chan *chan)
>> +					       struct dma_chan *chan,
>> +					       const char *name)
>>   {
>>   	int rc;
>>   
>> @@ -1066,8 +1067,10 @@ static int __dma_async_device_channel_register(struct dma_device *device,
>>   	chan->dev->device.parent = device->dev;
>>   	chan->dev->chan = chan;
>>   	chan->dev->dev_id = device->dev_id;
>> -	dev_set_name(&chan->dev->device, "dma%dchan%d",
>> -		     device->dev_id, chan->chan_id);
>> +	if (!name)
>> +		dev_set_name(&chan->dev->device, "dma%dchan%d", device->dev_id, chan->chan_id);
>> +	else
>> +		dev_set_name(&chan->dev->device, name);
>>   	rc = device_register(&chan->dev->device);
>>   	if (rc)
>>   		goto err_out_ida;
>> @@ -1087,11 +1090,12 @@ static int __dma_async_device_channel_register(struct dma_device *device,
>>   }
>>   
>>   int dma_async_device_channel_register(struct dma_device *device,
>> -				      struct dma_chan *chan)
>> +				      struct dma_chan *chan,
>> +				      const char *name)
>>   {
>>   	int rc;
>>   
>> -	rc = __dma_async_device_channel_register(device, chan);
>> +	rc = __dma_async_device_channel_register(device, chan, name);
>>   	if (rc < 0)
>>   		return rc;
>>   
>> @@ -1200,7 +1204,7 @@ int dma_async_device_register(struct dma_device *device)
>>   
>>   	/* represent channels in sysfs. Probably want devs too */
>>   	list_for_each_entry(chan, &device->channels, device_node) {
>> -		rc = __dma_async_device_channel_register(device, chan);
>> +		rc = __dma_async_device_channel_register(device, chan, NULL);
>>   		if (rc < 0)
>>   			goto err_out;
>>   	}
>> diff --git a/drivers/dma/idxd/dma.c b/drivers/dma/idxd/dma.c
>> index 47a01893cfdb..101a265567a9 100644
>> --- a/drivers/dma/idxd/dma.c
>> +++ b/drivers/dma/idxd/dma.c
>> @@ -269,7 +269,7 @@ static int idxd_register_dma_channel(struct idxd_wq *wq)
>>   		desc->txd.tx_submit = idxd_dma_tx_submit;
>>   	}
>>   
>> -	rc = dma_async_device_channel_register(dma, chan);
>> +	rc = dma_async_device_channel_register(dma, chan, NULL);
>>   	if (rc < 0) {
>>   		kfree(idxd_chan);
>>   		return rc;
>> diff --git a/include/linux/dmaengine.h b/include/linux/dmaengine.h
>> index 3df70d6131c8..cbad92cc3e0b 100644
>> --- a/include/linux/dmaengine.h
>> +++ b/include/linux/dmaengine.h
>> @@ -1574,7 +1574,8 @@ int dma_async_device_register(struct dma_device *device);
>>   int dmaenginem_async_device_register(struct dma_device *device);
>>   void dma_async_device_unregister(struct dma_device *device);
>>   int dma_async_device_channel_register(struct dma_device *device,
>> -				      struct dma_chan *chan);
>> +				      struct dma_chan *chan,
>> +				      const char *name);
>>   void dma_async_device_channel_unregister(struct dma_device *device,
>>   					 struct dma_chan *chan);
>>   void dma_run_dependencies(struct dma_async_tx_descriptor *tx);
>> -- 
>> 2.25.1
>