From mboxrd@z Thu Jan 1 00:00:00 1970 From: Mika Westerberg Subject: Re: [PATCH] spi/pxa2xx-pci: Enable DMA binding through device name Date: Thu, 24 Jul 2014 17:06:20 +0300 Message-ID: <20140724140620.GP1857@lahna.fi.intel.com> References: <1406196111-22861-1-git-send-email-hock.leong.kweh@intel.com> <10365151.12bEvS9Gvj@wuerfel> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Cc: linux-arm-kernel-IAPFreCvJWM7uuMidbF8XUB+6BGkLq7r@public.gmane.org, Kweh Hock Leong , Eric Miao , Russell King , Haojian Zhuang , Mark Brown , Chew Chiau Ee , Darren Hart , chiauee85-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org, linux-kernel-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, linux-spi-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, Andy Shevchenko To: Arnd Bergmann Return-path: Content-Disposition: inline In-Reply-To: <10365151.12bEvS9Gvj@wuerfel> Sender: linux-spi-owner-u79uwXL29TY76Z2rM5mHXA@public.gmane.org List-ID: 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" > > > > 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 > > Signed-off-by: Kweh, Hock Leong > > 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. -- To unsubscribe from this list: send the line "unsubscribe linux-spi" in the body of a message to majordomo-u79uwXL29TY76Z2rM5mHXA@public.gmane.org More majordomo info at http://vger.kernel.org/majordomo-info.html