[3.13.y.z extended stable] Patch "DRM: armada: fix corruption while loading cursors" has been added to staging queue

Kamal Mostafa kamal at canonical.com
Thu May 1 19:17:55 UTC 2014

This is a note to let you know that I have just added a patch titled

    DRM: armada: fix corruption while loading cursors

to the linux-3.13.y-queue branch of the 3.13.y.z extended stable tree 
which can be found at:


This patch is scheduled to be released in version

If you, or anyone else, feels it should not be added to this tree, please 
reply to this email.

For more information about the 3.13.y.z tree, see



>From ea2c40b5ea2d8249d4f47a2aa3a35519b3a9565a Mon Sep 17 00:00:00 2001
From: Russell King <rmk+kernel at arm.linux.org.uk>
Date: Mon, 7 Apr 2014 12:00:17 +0100
Subject: DRM: armada: fix corruption while loading cursors

commit c39b06951f1dc2e384650288676c5b7dcc0ec92c upstream.

Loading cursors to the LCD controller's SRAM can be corrupted when the
configured pixel clock is relatively slow.  This seems to be caused
when we write back-to-back to the SRAM registers.

There doesn't appear to be any status register we can read to check
when an access has completed.

Inserting a dummy read between the writes appears to fix the problem.

Signed-off-by: Russell King <rmk+kernel at arm.linux.org.uk>
Signed-off-by: Dave Airlie <airlied at redhat.com>
Signed-off-by: Kamal Mostafa <kamal at canonical.com>
 drivers/gpu/drm/armada/armada_crtc.c | 1 +
 1 file changed, 1 insertion(+)

diff --git a/drivers/gpu/drm/armada/armada_crtc.c b/drivers/gpu/drm/armada/armada_crtc.c
index d8e3982..66a492a 100644
--- a/drivers/gpu/drm/armada/armada_crtc.c
+++ b/drivers/gpu/drm/armada/armada_crtc.c
@@ -678,6 +678,7 @@ static void armada_load_cursor_argb(void __iomem *base, uint32_t *pix,
 				       base + LCD_SPU_SRAM_WRDAT);
 			writel_relaxed(addr | SRAM_WRITE,
 				       base + LCD_SPU_SRAM_CTRL);
+			readl_relaxed(base + LCD_SPU_HWC_OVSA_HPXL_VLN);
 			addr += 1;
 			if ((addr & 0x00ff) == 0)
 				addr += 0xf00;

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