linux-kernel - Re: [PATCH v2] media: rcar_drif: Use dma_request_chan() instead dma_request_slave

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Date:   Mon, 20 Jan 2020 14:49:12 +0200
From:   Peter Ujfalusi <peter.ujfalusi@...com>
To:     <mchehab@...nel.org>, <rashanmu@...il.com>, <geert@...ux-m68k.org>
CC:     <vkoul@...nel.org>, <linux-media@...r.kernel.org>,
        <linux-kernel@...r.kernel.org>, <linux-renesas-soc@...r.kernel.org>
Subject: Re: [PATCH v2] media: rcar_drif: Use dma_request_chan() instead
 dma_request_slave_channel()

Hi,


On 20/01/2020 14.47, Peter Ujfalusi wrote:
> dma_request_slave_channel() is a wrapper on top of dma_request_chan()
> eating up the error code.
> 
> By using dma_request_chan() directly the driver can support deferred
> probing against DMA.

yes, this is suppose to be v3, but missed to change the subject-prefix.

> Signed-off-by: Peter Ujfalusi <peter.ujfalusi@...com>
> Reviewed-by: Geert Uytterhoeven <geert+renesas@...der.be>
> ---
> Hi,
> 
> Changes since v2:
> - Use %pe to print error name using the ch->dmach pointer
> - Set ch->dmach to NULL in case of error
> 
> Changes since v1:
> - Do not print error in case of EPROBE_DEFER
> - Added Reviewed-by from Geert
> 
> Regards,
> Peter
> 
>  drivers/media/platform/rcar_drif.c | 12 ++++++++----
>  1 file changed, 8 insertions(+), 4 deletions(-)
> 
> diff --git a/drivers/media/platform/rcar_drif.c b/drivers/media/platform/rcar_drif.c
> index 0f267a237b42..3d2451ac347d 100644
> --- a/drivers/media/platform/rcar_drif.c
> +++ b/drivers/media/platform/rcar_drif.c
> @@ -275,10 +275,14 @@ static int rcar_drif_alloc_dmachannels(struct rcar_drif_sdr *sdr)
>  	for_each_rcar_drif_channel(i, &sdr->cur_ch_mask) {
>  		struct rcar_drif *ch = sdr->ch[i];
>  
> -		ch->dmach = dma_request_slave_channel(&ch->pdev->dev, "rx");
> -		if (!ch->dmach) {
> -			rdrif_err(sdr, "ch%u: dma channel req failed\n", i);
> -			ret = -ENODEV;
> +		ch->dmach = dma_request_chan(&ch->pdev->dev, "rx");
> +		if (IS_ERR(ch->dmach)) {
> +			ret = PTR_ERR(ch->dmach);
> +			if (ret != -EPROBE_DEFER)
> +				rdrif_err(sdr,
> +					  "ch%u: dma channel req failed: %pe\n",
> +					  i, ch->dmach);
> +			ch->dmach = NULL;
>  			goto dmach_error;
>  		}
>  
> 

- Péter

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