dma: mv_xor: Flush descriptors before activating a channel

commit 5a9a55bf9157d3490b0c8c4c81d4708602c26e07 upstream.

We need to use writel() instead of writel_relaxed() when starting
a channel, to ensure all the descriptors have been flushed before
the activation.

While at it, remove the unneeded read-modify-write and make the
code simpler.

Signed-off-by: Lior Amsalem <alior@marvell.com>
Signed-off-by: Ezequiel Garcia <ezequiel.garcia@free-electrons.com>
Signed-off-by: Dan Williams <dan.j.williams@intel.com>
[bwh: Backported to 3.2: it was using __raw_readl() and __raw_writel()
 which are just as wrong]
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>

diff --git a/drivers/dma/mv_xor.c b/drivers/dma/mv_xor.c
index 9a353c2216d09a1c1a498da4344f31a03f90aad3..9b01145e672374d8bf7a144f59b89964d9edf340 100644 (file)
--- a/drivers/dma/mv_xor.c
+++ b/drivers/dma/mv_xor.c
@@ -218,12 +218,10 @@ static void mv_set_mode(struct mv_xor_chan *chan,
 
 static void mv_chan_activate(struct mv_xor_chan *chan)
 {
-       u32 activation;
-
        dev_dbg(chan->device->common.dev, " activate chan.\n");
-       activation = __raw_readl(XOR_ACTIVATION(chan));
-       activation |= 0x1;
-       __raw_writel(activation, XOR_ACTIVATION(chan));
+
+       /* writel ensures all descriptors are flushed before activation */
+       writel(BIT(0), XOR_ACTIVATION(chan));
 }
 
 static char mv_chan_is_busy(struct mv_xor_chan *chan)