xiaomi-sm8450/android_kernel_xiaomi_sm8450
1
0
Fork 0
Code Issues Pull Requests Actions Packages Projects Releases Wiki Activity

dmaengine: ensure all DMA engine drivers initialize their cookies

Browse Source 
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 <rmk+kernel@arm.linux.org.uk>
Tested-by: Linus Walleij <linus.walleij@linaro.org>
Reviewed-by: Linus Walleij <linus.walleij@linaro.org>
Acked-by: Jassi Brar <jassisinghbrar@gmail.com>
[imx-sdma.c & mxs-dma.c]
Tested-by: Shawn Guo <shawn.guo@linaro.org>
Signed-off-by: Vinod Koul <vinod.koul@linux.intel.com>
This commit is contained in:
Russell King - ARM Linux
2012-03-06 22:36:27 +00:00
committed by Vinod Koul
parent 2a926e4602
commit 8ac695463f
9 changed files with 9 additions and 0 deletions
Download Patch File Download Diff File Expand all files Collapse all files

1
drivers/dma/ioat/dma.c
View File

@@ -109,6 +109,7 @@ void ioat_init_channel(struct ioatdma_device *device, struct ioat_chan_common *c
chan->reg_base = device->reg_base + (0x80 * (idx + 1));
spin_lock_init(&chan->cleanup_lock);
chan->common.device = dma;
dma_cookie_init(&chan->common);
list_add_tail(&chan->common.device_node, &dma->channels);
device->idx[idx] = chan;
init_timer(&chan->timer);