From: Russell King - ARM Linux Date: Tue, 6 Mar 2012 22:36:27 +0000 (+0000) Subject: dmaengine: ensure all DMA engine drivers initialize their cookies X-Git-Tag: v3.4-rc1~39^2~20^2~2 X-Git-Url: http://git.openpandora.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=8ac695463f37af902e953d575d3f782e32e170da;p=pandora-kernel.git dmaengine: ensure all DMA engine drivers initialize their cookies Ensure all DMA engine drivers initialize their cookies in the same way, so that they all behave in a similar fashion. This means their first issued cookie will be 2 rather than 1, and will increment to INT_MAX before returning 1 and starting over. In connection with this, Dan Williams said: > Russell King wrote: > > Secondly, some DMA engine drivers initialize the dma_chan cookie to 0, > > others to 1.  Is there a reason for this, or are these all buggy? > > I know that ioat and iop-adma expect 0 to mean "I have cleaned up this > descriptor and it is idle", and would break if zero was an in-flight > cookie value. The reserved usage of zero is an driver internal > concern, but I have no problem formalizing it as a reserved value. Signed-off-by: Russell King Tested-by: Linus Walleij Reviewed-by: Linus Walleij Acked-by: Jassi Brar [imx-sdma.c & mxs-dma.c] Tested-by: Shawn Guo Signed-off-by: Vinod Koul --- Reading git-diff-tree failed