[RFC,2/5] dmaengine: Add function to request slave channel from a dma_device

[RFC,2/5] dmaengine: Add function to request slave channel from a dma_device

[Peter Ujfalusi]

On 2018-10-09 14:22, Peter Ujfalusi wrote:
> 
> 
> On 2018-10-09 13:49, Vinod wrote:
>> On 24-09-18, 16:00, Peter Ujfalusi wrote:
>>> dma_get_any_slave_channel() would skip using the filter function, which
>>> in some cases needed to be executed before the alloc_chan_resources
>>> callback to make sure that all parameters are provided for the slave
>>> channel.
>>
>> Another request API, i though you had solved that last time around :(
> 
> Yes, I thought so, but this time it is different.
> I want to drop this patch myself also, but I need to figure out a way to
> do what the dmadev_get_slave_channel() allows me to do.
> 
> In path 4, udma_of_xlate() and the udma_dma_filter_fn()
> 
> It might be possible that I look up a free udma_chan, do the setup via
> the filter_fn() and finally call the dma_get_slave_channel().
> Might work fine, but I wanted to avoid to implement my own find free
> channel code when we have it already in DMAengine core.

It is going to be racy against parallel channel requests, but

>>> diff --git a/include/linux/dmaengine.h b/include/linux/dmaengine.h
>>> index 16c9d021988a..32010c6ae13a 100644
>>> --- a/include/linux/dmaengine.h
>>> +++ b/include/linux/dmaengine.h
>>> @@ -1542,6 +1542,8 @@ void dma_async_device_unregister(struct dma_device *device);
>>>  void dma_run_dependencies(struct dma_async_tx_descriptor *tx);
>>>  struct dma_chan *dma_get_slave_channel(struct dma_chan *chan);
>>>  struct dma_chan *dma_get_any_slave_channel(struct dma_device *device);
>>> +struct dma_chan *dmadev_get_slave_channel(struct dma_device *device,
>>> +					  dma_filter_fn fn, void *fn_param);

-struct dma_chan *dma_get_any_slave_channel(struct dma_device *device);
+struct dma_chan *dmadev_get_slave_channel(struct dma_device *device,
 				dma_filter_fn fn, void *fn_param);
+#define dma_get_any_slave_channel(device)\
	 dmadev_get_slave_channel(device, NULL, NULL)

Should cut down on duplicated code at least.


>>>  #define dma_request_channel(mask, x, y) __dma_request_channel(&(mask), x, y)
>>>  #define dma_request_slave_channel_compat(mask, x, y, dev, name) \
>>>  	__dma_request_slave_channel_compat(&(mask), x, y, dev, name)
>>> -- 
>>> Peter
>>>
>>> Texas Instruments Finland Oy, Porkkalankatu 22, 00180 Helsinki.
>>> Y-tunnus/Business ID: 0615521-4. Kotipaikka/Domicile: Helsinki
>>
> 
> - Péter
> 
> Texas Instruments Finland Oy, Porkkalankatu 22, 00180 Helsinki.
> Y-tunnus/Business ID: 0615521-4. Kotipaikka/Domicile: Helsinki
> 

- Péter

Texas Instruments Finland Oy, Porkkalankatu 22, 00180 Helsinki.
Y-tunnus/Business ID: 0615521-4. Kotipaikka/Domicile: Helsinki

[RFC,2/5] dmaengine: Add function to request slave channel from a dma_device

[Peter Ujfalusi]

On 2018-10-09 13:49, Vinod wrote:
> On 24-09-18, 16:00, Peter Ujfalusi wrote:
>> dma_get_any_slave_channel() would skip using the filter function, which
>> in some cases needed to be executed before the alloc_chan_resources
>> callback to make sure that all parameters are provided for the slave
>> channel.
> 
> Another request API, i though you had solved that last time around :(

Yes, I thought so, but this time it is different.
I want to drop this patch myself also, but I need to figure out a way to
do what the dmadev_get_slave_channel() allows me to do.

In path 4, udma_of_xlate() and the udma_dma_filter_fn()

It might be possible that I look up a free udma_chan, do the setup via
the filter_fn() and finally call the dma_get_slave_channel().
Might work fine, but I wanted to avoid to implement my own find free
channel code when we have it already in DMAengine core.

>>
>> Signed-off-by: Peter Ujfalusi <peter.ujfalusi@ti.com>
>> ---
>>  drivers/dma/dmaengine.c   | 20 ++++++++++++++++++++
>>  include/linux/dmaengine.h |  2 ++
>>  2 files changed, 22 insertions(+)
>>
>> diff --git a/drivers/dma/dmaengine.c b/drivers/dma/dmaengine.c
>> index 27b6d7c2d8a0..b80f1bdd8813 100644
>> --- a/drivers/dma/dmaengine.c
>> +++ b/drivers/dma/dmaengine.c
>> @@ -634,6 +634,26 @@ struct dma_chan *dma_get_any_slave_channel(struct dma_device *device)
>>  }
>>  EXPORT_SYMBOL_GPL(dma_get_any_slave_channel);
>>  
>> +struct dma_chan *dmadev_get_slave_channel(struct dma_device *device,
>> +					  dma_filter_fn fn, void *fn_param)
>> +{
>> +	dma_cap_mask_t mask;
>> +	struct dma_chan *chan;
>> +
>> +	dma_cap_zero(mask);
>> +	dma_cap_set(DMA_SLAVE, mask);
>> +
>> +	/* lock against __dma_request_channel */
>> +	mutex_lock(&dma_list_mutex);
>> +
>> +	chan = find_candidate(device, &mask, fn, fn_param);
>> +
>> +	mutex_unlock(&dma_list_mutex);
>> +
>> +	return IS_ERR(chan) ? NULL : chan;
>> +}
>> +EXPORT_SYMBOL_GPL(dmadev_get_slave_channel);
>> +
>>  /**
>>   * __dma_request_channel - try to allocate an exclusive channel
>>   * @mask: capabilities that the channel must satisfy
>> diff --git a/include/linux/dmaengine.h b/include/linux/dmaengine.h
>> index 16c9d021988a..32010c6ae13a 100644
>> --- a/include/linux/dmaengine.h
>> +++ b/include/linux/dmaengine.h
>> @@ -1542,6 +1542,8 @@ void dma_async_device_unregister(struct dma_device *device);
>>  void dma_run_dependencies(struct dma_async_tx_descriptor *tx);
>>  struct dma_chan *dma_get_slave_channel(struct dma_chan *chan);
>>  struct dma_chan *dma_get_any_slave_channel(struct dma_device *device);
>> +struct dma_chan *dmadev_get_slave_channel(struct dma_device *device,
>> +					  dma_filter_fn fn, void *fn_param);
>>  #define dma_request_channel(mask, x, y) __dma_request_channel(&(mask), x, y)
>>  #define dma_request_slave_channel_compat(mask, x, y, dev, name) \
>>  	__dma_request_slave_channel_compat(&(mask), x, y, dev, name)
>> -- 
>> Peter
>>
>> Texas Instruments Finland Oy, Porkkalankatu 22, 00180 Helsinki.
>> Y-tunnus/Business ID: 0615521-4. Kotipaikka/Domicile: Helsinki
> 

- Péter

Texas Instruments Finland Oy, Porkkalankatu 22, 00180 Helsinki.
Y-tunnus/Business ID: 0615521-4. Kotipaikka/Domicile: Helsinki

[RFC,2/5] dmaengine: Add function to request slave channel from a dma_device

[Vinod Koul]

On 24-09-18, 16:00, Peter Ujfalusi wrote:
> dma_get_any_slave_channel() would skip using the filter function, which
> in some cases needed to be executed before the alloc_chan_resources
> callback to make sure that all parameters are provided for the slave
> channel.

Another request API, i though you had solved that last time around :(

> 
> Signed-off-by: Peter Ujfalusi <peter.ujfalusi@ti.com>
> ---
>  drivers/dma/dmaengine.c   | 20 ++++++++++++++++++++
>  include/linux/dmaengine.h |  2 ++
>  2 files changed, 22 insertions(+)
> 
> diff --git a/drivers/dma/dmaengine.c b/drivers/dma/dmaengine.c
> index 27b6d7c2d8a0..b80f1bdd8813 100644
> --- a/drivers/dma/dmaengine.c
> +++ b/drivers/dma/dmaengine.c
> @@ -634,6 +634,26 @@ struct dma_chan *dma_get_any_slave_channel(struct dma_device *device)
>  }
>  EXPORT_SYMBOL_GPL(dma_get_any_slave_channel);
>  
> +struct dma_chan *dmadev_get_slave_channel(struct dma_device *device,
> +					  dma_filter_fn fn, void *fn_param)
> +{
> +	dma_cap_mask_t mask;
> +	struct dma_chan *chan;
> +
> +	dma_cap_zero(mask);
> +	dma_cap_set(DMA_SLAVE, mask);
> +
> +	/* lock against __dma_request_channel */
> +	mutex_lock(&dma_list_mutex);
> +
> +	chan = find_candidate(device, &mask, fn, fn_param);
> +
> +	mutex_unlock(&dma_list_mutex);
> +
> +	return IS_ERR(chan) ? NULL : chan;
> +}
> +EXPORT_SYMBOL_GPL(dmadev_get_slave_channel);
> +
>  /**
>   * __dma_request_channel - try to allocate an exclusive channel
>   * @mask: capabilities that the channel must satisfy
> diff --git a/include/linux/dmaengine.h b/include/linux/dmaengine.h
> index 16c9d021988a..32010c6ae13a 100644
> --- a/include/linux/dmaengine.h
> +++ b/include/linux/dmaengine.h
> @@ -1542,6 +1542,8 @@ void dma_async_device_unregister(struct dma_device *device);
>  void dma_run_dependencies(struct dma_async_tx_descriptor *tx);
>  struct dma_chan *dma_get_slave_channel(struct dma_chan *chan);
>  struct dma_chan *dma_get_any_slave_channel(struct dma_device *device);
> +struct dma_chan *dmadev_get_slave_channel(struct dma_device *device,
> +					  dma_filter_fn fn, void *fn_param);
>  #define dma_request_channel(mask, x, y) __dma_request_channel(&(mask), x, y)
>  #define dma_request_slave_channel_compat(mask, x, y, dev, name) \
>  	__dma_request_slave_channel_compat(&(mask), x, y, dev, name)
> -- 
> Peter
> 
> Texas Instruments Finland Oy, Porkkalankatu 22, 00180 Helsinki.
> Y-tunnus/Business ID: 0615521-4. Kotipaikka/Domicile: Helsinki

[RFC,2/5] dmaengine: Add function to request slave channel from a dma_device

[Peter Ujfalusi]

dma_get_any_slave_channel() would skip using the filter function, which
in some cases needed to be executed before the alloc_chan_resources
callback to make sure that all parameters are provided for the slave
channel.

Signed-off-by: Peter Ujfalusi <peter.ujfalusi@ti.com>
---
 drivers/dma/dmaengine.c   | 20 ++++++++++++++++++++
 include/linux/dmaengine.h |  2 ++
 2 files changed, 22 insertions(+)

diff --git a/drivers/dma/dmaengine.c b/drivers/dma/dmaengine.c
index 27b6d7c2d8a0..b80f1bdd8813 100644
--- a/drivers/dma/dmaengine.c
+++ b/drivers/dma/dmaengine.c
@@ -634,6 +634,26 @@ struct dma_chan *dma_get_any_slave_channel(struct dma_device *device)
 }
 EXPORT_SYMBOL_GPL(dma_get_any_slave_channel);
 
+struct dma_chan *dmadev_get_slave_channel(struct dma_device *device,
+					  dma_filter_fn fn, void *fn_param)
+{
+	dma_cap_mask_t mask;
+	struct dma_chan *chan;
+
+	dma_cap_zero(mask);
+	dma_cap_set(DMA_SLAVE, mask);
+
+	/* lock against __dma_request_channel */
+	mutex_lock(&dma_list_mutex);
+
+	chan = find_candidate(device, &mask, fn, fn_param);
+
+	mutex_unlock(&dma_list_mutex);
+
+	return IS_ERR(chan) ? NULL : chan;
+}
+EXPORT_SYMBOL_GPL(dmadev_get_slave_channel);
+
 /**
  * __dma_request_channel - try to allocate an exclusive channel
  * @mask: capabilities that the channel must satisfy
diff --git a/include/linux/dmaengine.h b/include/linux/dmaengine.h
index 16c9d021988a..32010c6ae13a 100644
--- a/include/linux/dmaengine.h
+++ b/include/linux/dmaengine.h
@@ -1542,6 +1542,8 @@ void dma_async_device_unregister(struct dma_device *device);
 void dma_run_dependencies(struct dma_async_tx_descriptor *tx);
 struct dma_chan *dma_get_slave_channel(struct dma_chan *chan);
 struct dma_chan *dma_get_any_slave_channel(struct dma_device *device);
+struct dma_chan *dmadev_get_slave_channel(struct dma_device *device,
+					  dma_filter_fn fn, void *fn_param);
 #define dma_request_channel(mask, x, y) __dma_request_channel(&(mask), x, y)
 #define dma_request_slave_channel_compat(mask, x, y, dev, name) \
 	__dma_request_slave_channel_compat(&(mask), x, y, dev, name)