Messages in this thread | | | Subject | Re: [PATCH] dw_dmac: adjust slave_id accordingly to request line base | From | Andy Shevchenko <> | Date | Wed, 30 Jan 2013 09:32:56 +0200 |
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On Tue, 2013-01-29 at 20:57 +0530, Viresh Kumar wrote: > On Tue, Jan 29, 2013 at 10:52 AM, Mika Westerberg > <mika.westerberg@linux.intel.com> wrote: > > We had a discusssion about this with Andy as well. The thing is that there > > is no way in current resource to pass DMA request line numbers supported by > > the controller to the driver in a generic way. We on the other hand have to > > deal this somehow as we have a shared DMA controller on Lynxpoint where the > > offset will start from 16 (but it might be something else as well). > > > > Is there something which limits the usage of IORESOUCE_DMA to be only > > usable for ISA DMA channels? > > Andy, > > Why do we need this request_line_base? Why not program the actual value > directly into the slave structure (base + offset)?
Slave device exactly has knowledge about this number slave_id = (base +offset). However...
> In case it is required, add it in platform data field or can add DT > binding for it.
We get a device from the ACPI CSRT table. During enumeration we don't know what kind of the device it is. From the enumeration point of view each device enumerated from CSRT is a platform device (see drivers/acpi/csrt.c for the details).
That's why we have to pass this info somehow to the DMAC driver. And like Mika already mentioned we have no other generic way except IORESOURCE_DMA. If you have something better in mind, please share. We could adopt our code then.
-- Andy Shevchenko <andriy.shevchenko@linux.intel.com> Intel Finland Oy
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