dma: mv_xor: clear the window override control registers

The XOR channels on Marvell SoCs have a Window Override Control
register that allow to do some fancy things with addresses. Those
features are not used by the driver, but some U-Boot versions anyway
modify those registers.

For some reason, the U-Boot on OpenBlocks AX3-4 was setting an invalid
value in those registers when the addition 2 GB DRAM chip was plugged
into the board, causing the XOR driver to fail in using the XOR
engines.

By setting those registers to 0 during the driver initialization, we
ensure that the registers are configured according with the driver
operation model.

Thanks to Lior Amsalem <alior@marvell.com> for his help in debugging
this problem.

Signed-off-by: Thomas Petazzoni <thomas.petazzoni@free-electrons.com>

1 files changed, 2 insertions, 0 deletions

diff --git a/drivers/dma/mv_xor.c b/drivers/dma/mv_xor.c
index f450fe8cbd61..2c69b89eac4f 100644
--- a/drivers/dma/mv_xor.c
+++ b/drivers/dma/mv_xor.c
@@ -1240,6 +1240,8 @@ mv_xor_conf_mbus_windows(struct mv_xor_device *xordev,
 
         writel(win_enable, base + WINDOW_BAR_ENABLE(0));
         writel(win_enable, base + WINDOW_BAR_ENABLE(1));
+        writel(0, base + WINDOW_OVERRIDE_CTRL(0));
+        writel(0, base + WINDOW_OVERRIDE_CTRL(1));
 }
 
 static int __devinit mv_xor_probe(struct platform_device *pdev)