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SubjectRe: [PATCH v2] media: omap3isp: Use dma_request_chan_by_mask() to request the DMA channel
Date
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 <peter.ujfalusi@ti.com>
> CC: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
> CC: Mauro Carvalho Chehab <mchehab@osg.samsung.com>

Reviewed-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>

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 <linux/delay.h>
> #include <linux/device.h>
> #include <linux/dmaengine.h>
> -#include <linux/omap-dmaengine.h>
> #include <linux/slab.h>
> #include <linux/uaccess.h>
>
> @@ -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(&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, &sig, 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 = &hist_ops;

--
Regards,

Laurent Pinchart

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