Re: [PATCH 1/8] dmaengine: Add matching device node validation in __dma_request_channel()

[Peter Ujfalusi <peter.ujfalusi@ti.com>]

Hi,

On 07/05/2019 9.09, Baolin Wang wrote:
> When user try to request one DMA channel by __dma_request_channel(), it won't
> validate if it is the correct DMA device to request, that will lead each DMA
> engine driver to validate the correct device node in their filter function
> if it is necessary.
> 
> Thus we can add the matching device node validation in the DMA engine core,
> to remove all of device node validation in the drivers.

I have picked this patch to my TI UDMA series and with
__dma_request_channel() it works as expected - picking the channel from
the correct DMA device.

Tested-by: Peter Ujfalusi <peter.ujfalusi@ti.com>

> 
> Signed-off-by: Baolin Wang <baolin.wang@linaro.org>
> ---
>  drivers/dma/dmaengine.c   |   10 ++++++++--
>  drivers/dma/of-dma.c      |    4 ++--
>  include/linux/dmaengine.h |   12 ++++++++----
>  3 files changed, 18 insertions(+), 8 deletions(-)
> 
> diff --git a/drivers/dma/dmaengine.c b/drivers/dma/dmaengine.c
> index 3a11b10..610080c 100644
> --- a/drivers/dma/dmaengine.c
> +++ b/drivers/dma/dmaengine.c
> @@ -641,11 +641,13 @@ struct dma_chan *dma_get_any_slave_channel(struct dma_device *device)
>   * @mask: capabilities that the channel must satisfy
>   * @fn: optional callback to disposition available channels
>   * @fn_param: opaque parameter to pass to dma_filter_fn
> + * @np: device node to look for DMA channels
>   *
>   * Returns pointer to appropriate DMA channel on success or NULL.
>   */
>  struct dma_chan *__dma_request_channel(const dma_cap_mask_t *mask,
> -				       dma_filter_fn fn, void *fn_param)
> +				       dma_filter_fn fn, void *fn_param,
> +				       struct device_node *np)
>  {
>  	struct dma_device *device, *_d;
>  	struct dma_chan *chan = NULL;
> @@ -653,6 +655,10 @@ struct dma_chan *__dma_request_channel(const dma_cap_mask_t *mask,
>  	/* Find a channel */
>  	mutex_lock(&dma_list_mutex);
>  	list_for_each_entry_safe(device, _d, &dma_device_list, global_node) {
> +		/* Finds a DMA controller with matching device node */
> +		if (np && device->dev->of_node && np != device->dev->of_node)
> +			continue;
> +
>  		chan = find_candidate(device, mask, fn, fn_param);
>  		if (!IS_ERR(chan))
>  			break;
> @@ -769,7 +775,7 @@ struct dma_chan *dma_request_chan_by_mask(const dma_cap_mask_t *mask)
>  	if (!mask)
>  		return ERR_PTR(-ENODEV);
>  
> -	chan = __dma_request_channel(mask, NULL, NULL);
> +	chan = __dma_request_channel(mask, NULL, NULL, NULL);
>  	if (!chan) {
>  		mutex_lock(&dma_list_mutex);
>  		if (list_empty(&dma_device_list))
> diff --git a/drivers/dma/of-dma.c b/drivers/dma/of-dma.c
> index 91fd395..6b43d04 100644
> --- a/drivers/dma/of-dma.c
> +++ b/drivers/dma/of-dma.c
> @@ -316,8 +316,8 @@ struct dma_chan *of_dma_simple_xlate(struct of_phandle_args *dma_spec,
>  	if (count != 1)
>  		return NULL;
>  
> -	return dma_request_channel(info->dma_cap, info->filter_fn,
> -			&dma_spec->args[0]);
> +	return __dma_request_channel(&info->dma_cap, info->filter_fn,
> +				     &dma_spec->args[0], dma_spec->np);
>  }
>  EXPORT_SYMBOL_GPL(of_dma_simple_xlate);
>  
> diff --git a/include/linux/dmaengine.h b/include/linux/dmaengine.h
> index d49ec5c..504085b 100644
> --- a/include/linux/dmaengine.h
> +++ b/include/linux/dmaengine.h
> @@ -1314,7 +1314,8 @@ static inline enum dma_status dma_async_is_complete(dma_cookie_t cookie,
>  enum dma_status dma_wait_for_async_tx(struct dma_async_tx_descriptor *tx);
>  void dma_issue_pending_all(void);
>  struct dma_chan *__dma_request_channel(const dma_cap_mask_t *mask,
> -					dma_filter_fn fn, void *fn_param);
> +				       dma_filter_fn fn, void *fn_param,
> +				       struct device_node *np);
>  struct dma_chan *dma_request_slave_channel(struct device *dev, const char *name);
>  
>  struct dma_chan *dma_request_chan(struct device *dev, const char *name);
> @@ -1339,7 +1340,9 @@ static inline void dma_issue_pending_all(void)
>  {
>  }
>  static inline struct dma_chan *__dma_request_channel(const dma_cap_mask_t *mask,
> -					      dma_filter_fn fn, void *fn_param)
> +						     dma_filter_fn fn,
> +						     void *fn_param,
> +						     struct device_node *np)
>  {
>  	return NULL;
>  }
> @@ -1411,7 +1414,8 @@ static inline int dmaengine_desc_free(struct dma_async_tx_descriptor *desc)
>  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);
> -#define dma_request_channel(mask, x, y) __dma_request_channel(&(mask), x, y)
> +#define dma_request_channel(mask, x, y) \
> +	__dma_request_channel(&(mask), x, y, NULL)
>  #define dma_request_slave_channel_compat(mask, x, y, dev, name) \
>  	__dma_request_slave_channel_compat(&(mask), x, y, dev, name)
>  
> @@ -1429,6 +1433,6 @@ static inline int dmaengine_desc_free(struct dma_async_tx_descriptor *desc)
>  	if (!fn || !fn_param)
>  		return NULL;
>  
> -	return __dma_request_channel(mask, fn, fn_param);
> +	return __dma_request_channel(mask, fn, fn_param, NULL);
>  }
>  #endif /* DMAENGINE_H */
> 

- Péter

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