Re: [PATCH v2] media: omap3isp: Use dma_request_chan_by_mask() to request the DMA channel

[Laurent Pinchart]

Hi Peter,

Thank you for the patch.

On Friday 04 Nov 2016 09:58:02 Peter Ujfalusi wrote:
> When requesting the DMA channel it was mandatory that we do not have DMA
> resource nor valid DMA channel via DT. In this case the
> dma_request_slave_channel_compat() would fall back and request any channel
> with SW trigger.
> 
> The same can be achieved with the dma_request_chan_by_mask() without the
> misleading use of the DMAengine API - implying that the omap3isp does
> need to have DMA resource or valid dma binding in DT.
> 
> Signed-off-by: Peter Ujfalusi 
> CC: Laurent Pinchart 
> CC: Mauro Carvalho Chehab 

Reviewed-by: Laurent Pinchart 

and added to my tree.

> ---
> Hi,
> 
> Changes sicne v1:
> - use dma_request_chan_by_mask() to request the channel as for the histogram
> data reading we do not have hw syncronisation. Add comment about this also
> to clarify the reason.
> 
> Regards,
> Peter
> 
>  drivers/media/platform/omap3isp/isphist.c | 28 +++-
> 1 file changed, 15 insertions(+), 13 deletions(-)
> 
> diff --git a/drivers/media/platform/omap3isp/isphist.c
> b/drivers/media/platform/omap3isp/isphist.c index
> 7138b043a4aa..a4ed5d140d48 100644
> --- a/drivers/media/platform/omap3isp/isphist.c
> +++ b/drivers/media/platform/omap3isp/isphist.c
> @@ -18,7 +18,6 @@
>  #include 
>  #include 
>  #include 
> -#include 
>  #include 
>  #include 
> 
> @@ -486,27 +485,30 @@ int omap3isp_hist_init(struct isp_device *isp)
>   hist->isp = isp;
> 
>   if (HIST_CONFIG_DMA) {
> - struct platform_device *pdev = to_platform_device(isp->dev);
> - struct resource *res;
> - unsigned int sig = 0;
>   dma_cap_mask_t mask;
> 
> + /*
> +  * We need slave capable channel without DMA request line for
> +  * reading out the data.
> +  * For this we can use dma_request_chan_by_mask() as we are
> +  * happy with any channel as long as it is capable of slave
> +  * configuration.
> +  */
>   dma_cap_zero(mask);
>   dma_cap_set(DMA_SLAVE, mask);
> + hist->dma_ch = dma_request_chan_by_mask();
> + if (IS_ERR(hist->dma_ch)) {
> + ret = PTR_ERR(hist->dma_ch);
> + if (ret == -EPROBE_DEFER)
> + return ret;
> 
> - res = platform_get_resource_byname(pdev, IORESOURCE_DMA,
> -"hist");
> - if (res)
> - sig = res->start;
> -
> - hist->dma_ch = dma_request_slave_channel_compat(mask,
> - omap_dma_filter_fn, , isp->dev, "hist");
> - if (!hist->dma_ch)
> + hist->dma_ch = NULL;
>   dev_warn(isp->dev,
>"hist: DMA channel request failed, using 
PIO\n");
> - else
> + } else {
>   dev_dbg(isp->dev, "hist: using DMA channel %s\n",
>   dma_chan_name(hist->dma_ch));
> + }
>   }
> 
>   hist->ops = _ops;

-- 
Regards,

Laurent Pinchart

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[PATCH v2] media: omap3isp: Use dma_request_chan_by_mask() to request the DMA channel

[Peter Ujfalusi]

When requesting the DMA channel it was mandatory that we do not have DMA
resource nor valid DMA channel via DT. In this case the
dma_request_slave_channel_compat() would fall back and request any channel
with SW trigger.

The same can be achieved with the dma_request_chan_by_mask() without the
misleading use of the DMAengine API - implying that the omap3isp does
need to have DMA resource or valid dma binding in DT.

Signed-off-by: Peter Ujfalusi 
CC: Laurent Pinchart 
CC: Mauro Carvalho Chehab 
---
Hi,

Changes sicne v1:
- use dma_request_chan_by_mask() to request the channel as for the histogram
  data reading we do not have hw syncronisation. Add comment about this also to
  clarify the reason.

Regards,
Peter

 drivers/media/platform/omap3isp/isphist.c | 28 +++-
 1 file changed, 15 insertions(+), 13 deletions(-)

diff --git a/drivers/media/platform/omap3isp/isphist.c 
b/drivers/media/platform/omap3isp/isphist.c
index 7138b043a4aa..a4ed5d140d48 100644
--- a/drivers/media/platform/omap3isp/isphist.c
+++ b/drivers/media/platform/omap3isp/isphist.c
@@ -18,7 +18,6 @@
 #include 
 #include 
 #include 
-#include 
 #include 
 #include 
 
@@ -486,27 +485,30 @@ int omap3isp_hist_init(struct isp_device *isp)
hist->isp = isp;
 
if (HIST_CONFIG_DMA) {
-   struct platform_device *pdev = to_platform_device(isp->dev);
-   struct resource *res;
-   unsigned int sig = 0;
dma_cap_mask_t mask;
 
+   /*
+* We need slave capable channel without DMA request line for
+* reading out the data.
+* For this we can use dma_request_chan_by_mask() as we are
+* happy with any channel as long as it is capable of slave
+* configuration.
+*/
dma_cap_zero(mask);
dma_cap_set(DMA_SLAVE, mask);
+   hist->dma_ch = dma_request_chan_by_mask();
+   if (IS_ERR(hist->dma_ch)) {
+   ret = PTR_ERR(hist->dma_ch);
+   if (ret == -EPROBE_DEFER)
+   return ret;
 
-   res = platform_get_resource_byname(pdev, IORESOURCE_DMA,
-  "hist");
-   if (res)
-   sig = res->start;
-
-   hist->dma_ch = dma_request_slave_channel_compat(mask,
-   omap_dma_filter_fn, , isp->dev, "hist");
-   if (!hist->dma_ch)
+   hist->dma_ch = NULL;
dev_warn(isp->dev,
 "hist: DMA channel request failed, using 
PIO\n");
-   else
+   } else {
dev_dbg(isp->dev, "hist: using DMA channel %s\n",
dma_chan_name(hist->dma_ch));
+   }
}
 
hist->ops = _ops;
-- 
2.10.2

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