From mboxrd@z Thu Jan 1 00:00:00 1970 From: linux@arm.linux.org.uk (Russell King - ARM Linux) Date: Fri, 29 Jul 2011 13:43:46 +0100 Subject: [PATCH 00/18] dmaengine/amba-pl08x updates In-Reply-To: <4E329848.7070606@st.com> References: <20110729105759.GE25640@n2100.arm.linux.org.uk> <4E329616.2030505@st.com> <20110729111920.GK25640@n2100.arm.linux.org.uk> <4E329848.7070606@st.com> Message-ID: <20110729124346.GL25640@n2100.arm.linux.org.uk> To: linux-arm-kernel@lists.infradead.org List-Id: linux-arm-kernel.lists.infradead.org On Fri, Jul 29, 2011 at 04:53:52PM +0530, viresh kumar wrote: > On 07/29/2011 04:49 PM, Russell King - ARM Linux wrote: > > Ok, so lets have the driver explicitly enforce one SG entry if peripheral > > flow is set. It would also be a good idea to pass not zero length, but > > the real transfer size in the SG entry for the sake of having the API > > know the full information about the transfer. > > In my case, JPEG driver doesn't know how much data to transfer. So i have to > send zero from there. Also, i am not sure why would peripheral needs to be > flow controller if the peripherals driver already know how much to transfer? If the jpeg driver doesn't know how much data will be transferred, how can it allocate a buffer for the device to DMA into?