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SubjectRe: [PATCH] dw_dmac: don't exceed AHB master number in dwc_get_data_width
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On Mon, Jan 14, 2013 at 7:50 PM, Andy Shevchenko
<andriy.shevchenko@linux.intel.com> wrote:
> The driver's default assumes that hardware has two AHB masters which might be
> not true. In such rare cases we have not to exceed a number of the AHB masters
> present in the hardware. Thus, the AHB master with highest possible number will
> be used to retrieve the data witdh value.
>
> The patch also changes the logic a bit when the master parameter of the
> dwc_get_data_width() is out of range. Now the function will return a value
> related to the first AHB master.
>
> Signed-off-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
> ---
> drivers/dma/dw_dmac.c | 7 ++++---
> 1 file changed, 4 insertions(+), 3 deletions(-)
>
> diff --git a/drivers/dma/dw_dmac.c b/drivers/dma/dw_dmac.c
> index 30ff2a4..b2d564a 100644
> --- a/drivers/dma/dw_dmac.c
> +++ b/drivers/dma/dw_dmac.c
> @@ -80,13 +80,14 @@ static inline unsigned int dwc_get_data_width(struct dma_chan *chan, int master)
> {
> struct dw_dma *dw = to_dw_dma(chan->device);
> struct dw_dma_slave *dws = chan->private;
> + unsigned int m = 0;
>
> if (master == SRC_MASTER)
> - return dw->data_width[dwc_get_sms(dws)];
> + m = dwc_get_sms(dws);
> else if (master == DST_MASTER)
> - return dw->data_width[dwc_get_dms(dws)];
> + m = dwc_get_dms(dws);
>
> - return 0;
> + return dw->data_width[min_t(unsigned int, dw->nr_masters - 1, m)];

The details of the patch are fine, but i didn't get how do you get
master 1 selected
on a system where you have only 1 master?


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