Messages in this thread | | | Date | Thu, 24 Jul 2014 17:06:20 +0300 | From | Mika Westerberg <> | Subject | Re: [PATCH] spi/pxa2xx-pci: Enable DMA binding through device name |
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On Thu, Jul 24, 2014 at 01:42:10PM +0200, Arnd Bergmann wrote: > On Thursday 24 July 2014 18:01:51 Kweh Hock Leong wrote: > > From: "Chew, Chiau Ee" <chiau.ee.chew@intel.com> > > > > Intel LPSS Baytrail supports two DMA controllers and SPI is only > > using one of the DMA controller. During DMA channel request, > > we need to ensure the requested Tx and Rx channels are from the correct > > DMA controller. Thus, we add extra checking in filter callback funtion > > by matching against the DMA controller device name. > > > > Signed-off-by: Chew, Chiau Ee <chiau.ee.chew@intel.com> > > Signed-off-by: Kweh, Hock Leong <hock.leong.kweh@intel.com> > > I'm confused. Doesn't Bay Trail use ACPI to do the DMA > engine configuration? That should set find the right device/chan_id/slave_id > combination without any interaction, through the use of dma_request_slave_channel.
It is also possible that the corresponding Baytrail system doesn't have ACPI enabled BIOS in which case it dma_request_slave_channel() doesn't help here.
> On a related note, there seems to be a bug in this driver, which > attempts to set the slave_id through dmaengine_slave_config(), which > is wrong in both cases, ACPI and filter functions.
Good point. We will fix this, thanks.
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