On Tue, Jan 15, 2013 at 3:54 AM, Viresh Kumar <viresh.ku...@linaro.org> wrote:
> On Mon, Jan 14, 2013 at 7:50 PM, Andy Shevchenko
> <andriy.shevche...@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.shevche...@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?
min_t(..., nr_masters - 1, m) defines this. m is returned value with
default settings, let's say 1. In that case if nr_masters is also 1
the min_t(..., 1-1, 1) returns 0.
The value of nr_masters itself is come from autoconfig or platform data.
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--
With Best Regards,
Andy Shevchenko
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