On Thu, 2013-09-19 at 22:55 +0100, Russell King wrote:
> This code sequence:
> if (!pdev->dev.dma_mask) {
> pdev->dev.dma_mask = &pdev->dev.coherent_dma_mask;
> pdev->dev.coherent_dma_mask = DMA_BIT_MASK(32);
> }
> bypasses the architectures check on the DMA mask. It can be replaced
> with dma_coerce_mask_and_coherent(), avoiding the direct initialization
> of this mask.
>
> Signed-off-by: Russell King <[email protected]>
> ---
> drivers/dma/dw/platform.c | 8 +++-----
> 1 files changed, 3 insertions(+), 5 deletions(-)
>
> diff --git a/drivers/dma/dw/platform.c b/drivers/dma/dw/platform.c
> index e35d975..453822c 100644
> --- a/drivers/dma/dw/platform.c
> +++ b/drivers/dma/dw/platform.c
> @@ -191,11 +191,9 @@ static int dw_probe(struct platform_device *pdev)
> if (IS_ERR(chip->regs))
> return PTR_ERR(chip->regs);
>
> - /* Apply default dma_mask if needed */
> - if (!dev->dma_mask) {
> - dev->dma_mask = &dev->coherent_dma_mask;
> - dev->coherent_dma_mask = DMA_BIT_MASK(32);
> - }
> + err = dma_coerce_mask_and_coherent(&pdev->dev, DMA_BIT_MASK(32));
> + if (err)
> + return err;
I have at least one question.
In case of new code you always assign dev->dma_mask.
static inline int dma_coerce_mask_and_coherent(struct device *dev, u64
mask)
{
dev->dma_mask = &dev->coherent_dma_mask;
return dma_set_mask_and_coherent(dev, mask);
}
So, the question is how keep the initialized dma_mask (and should we do
so by your opinion)?
Additional question, who will free memory allocated for dma_mask in case
if it was allocated, dma_mask initialized and then your code just
substitute the address to some new value?
--
Andy Shevchenko <[email protected]>
Intel Finland Oy
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