linux-kernel - Re: [PATCH v3 05/59] dmaengine: Make channel allocation callbacks optional

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Message-ID: <17062495.59UaxHxT3Y@avalon>
Date:	Thu, 23 Oct 2014 00:05:13 +0300
From:	Laurent Pinchart <laurent.pinchart@...asonboard.com>
To:	Maxime Ripard <maxime.ripard@...e-electrons.com>
Cc:	dmaengine@...r.kernel.org, Vinod Koul <vinod.koul@...el.com>,
	linux-arm-kernel@...ts.infradead.org, linux-kernel@...r.kernel.org,
	Antoine Ténart <antoine@...e-electrons.com>,
	lars@...afoo.de, Russell King <linux@....linux.org.uk>,
	Dan Williams <dan.j.williams@...el.com>
Subject: Re: [PATCH v3 05/59] dmaengine: Make channel allocation callbacks optional

Hi Maxime,

Thank you for the patch.

On Wednesday 22 October 2014 17:43:19 Maxime Ripard wrote:
> Nowadays, some drivers don't have anything in there channel allocation
> callbacks anymore.
> 
> Remove the BUG_ON if those callbacks aren't implemented, in order to allow
> drivers to not implement them.
> 
> Signed-off-by: Maxime Ripard <maxime.ripard@...e-electrons.com>

Acked-by: Laurent Pinchart <laurent.pinchart@...asonboard.com>

> ---
>  drivers/dma/dmaengine.c | 18 +++++++++++-------
>  1 file changed, 11 insertions(+), 7 deletions(-)
> 
> diff --git a/drivers/dma/dmaengine.c b/drivers/dma/dmaengine.c
> index 72f10e2f5c32..9b2cd74b8f2e 100644
> --- a/drivers/dma/dmaengine.c
> +++ b/drivers/dma/dmaengine.c
> @@ -235,9 +235,11 @@ static int dma_chan_get(struct dma_chan *chan)
>  		return -ENODEV;
> 
>  	/* allocate upon first client reference */
> -	ret = chan->device->device_alloc_chan_resources(chan);
> -	if (ret < 0)
> -		goto err_out;
> +	if (chan->device->device_alloc_chan_resources) {
> +		ret = chan->device->device_alloc_chan_resources(chan);
> +		if (ret < 0)
> +			goto err_out;
> +	}
> 
>  	if (!dma_has_cap(DMA_PRIVATE, chan->device->cap_mask))
>  		balance_ref_count(chan);
> @@ -259,11 +261,15 @@ err_out:
>   */
>  static void dma_chan_put(struct dma_chan *chan)
>  {
> +	/* This channel is not in use, bail out */
>  	if (!chan->client_count)
> -		return; /* this channel failed alloc_chan_resources */
> +		return;
> +
>  	chan->client_count--;
>  	module_put(dma_chan_to_owner(chan));
> -	if (chan->client_count == 0)
> +
> +	/* This channel is not in use anymore, free it */
> +	if (!chan->client_count && chan->device->device_free_chan_resources)
>  		chan->device->device_free_chan_resources(chan);
>  }
> 
> @@ -819,8 +825,6 @@ int dma_async_device_register(struct dma_device *device)
> BUG_ON(dma_has_cap(DMA_INTERLEAVE, device->cap_mask) &&
>  		!device->device_prep_interleaved_dma);
> 
> -	BUG_ON(!device->device_alloc_chan_resources);
> -	BUG_ON(!device->device_free_chan_resources);
>  	BUG_ON(!device->device_tx_status);
>  	BUG_ON(!device->device_issue_pending);
>  	BUG_ON(!device->dev);

-- 
Regards,

Laurent Pinchart

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