Re: [PATCH 00/18] dmaengine/amba-pl08x updates

From: Russell King - ARM Linux
Date: Fri Jul 29 2011 - 08:44:10 EST


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?
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