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:

quoted

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?