linux-kernel - Re: [PATCH] mmc: bcm2835: Use dma_request_chan() instead dma_request_slave

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Message-ID: <cd316378273d18b93b5dcad8b357821a708c7805.camel@suse.de>
Date:   Tue, 17 Dec 2019 12:37:25 +0100
From:   Nicolas Saenz Julienne <nsaenzjulienne@...e.de>
To:     Peter Ujfalusi <peter.ujfalusi@...com>, ulf.hansson@...aro.org,
        f.fainelli@...il.com, rjui@...adcom.com, sbranden@...adcom.com
Cc:     vkoul@...nel.org, linux-mmc@...r.kernel.org,
        linux-kernel@...r.kernel.org,
        bcm-kernel-feedback-list@...adcom.com,
        linux-rpi-kernel@...ts.infradead.org,
        linux-arm-kernel@...ts.infradead.org
Subject: Re: [PATCH] mmc: bcm2835: Use dma_request_chan() instead
 dma_request_slave_channel()

Hi Peter,

On Tue, 2019-12-17 at 13:26 +0200, 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.
> 
> Signed-off-by: Peter Ujfalusi <peter.ujfalusi@...com>
> ---
>  drivers/mmc/host/bcm2835.c | 10 +++++++++-
>  1 file changed, 9 insertions(+), 1 deletion(-)
> 
> diff --git a/drivers/mmc/host/bcm2835.c b/drivers/mmc/host/bcm2835.c
> index 99f61fd2a658..3821f159d36d 100644
> --- a/drivers/mmc/host/bcm2835.c
> +++ b/drivers/mmc/host/bcm2835.c
> @@ -1393,7 +1393,15 @@ static int bcm2835_probe(struct platform_device *pdev)
>  	host->dma_chan = NULL;
>  	host->dma_desc = NULL;
>  
> -	host->dma_chan_rxtx = dma_request_slave_channel(dev, "rx-tx");
> +	host->dma_chan_rxtx = dma_request_chan(dev, "rx-tx");
> +	if (IS_ERR(host->dma_chan_rxtx)) {
> +		if (PTR_ERR(host->dma_chan_rxtx) == -EPROBE_DEFER)
> +			return -EPROBE_DEFER;

I think you should 'goto err' here, as you have to free the mmc host structure
allocated earlier in the probe function.

Other than that the patch looks good to me.

Regards,
Nicolas


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