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由 Russell King - ARM Linux 提交于
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: NRussell King <rmk+kernel@arm.linux.org.uk> Tested-by: NLinus Walleij <linus.walleij@linaro.org> Reviewed-by: NLinus Walleij <linus.walleij@linaro.org> Acked-by: NJassi Brar <jassisinghbrar@gmail.com> [imx-sdma.c & mxs-dma.c] Tested-by: NShawn Guo <shawn.guo@linaro.org> Signed-off-by: NVinod Koul <vinod.koul@linux.intel.com>
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