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.
Cc: stable@vger.kernel.org # 3.13 Signed-off-by: Russell King rmk+kernel@arm.linux.org.uk --- David,
Could you take this patch - it's also a good idea that it's back ported to stable kernels as it affects all releases which this driver has been in. I don't see the need for a pull request as this is just a single patch.
Thanks.
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 19ffd5c22944..357e5eb59e89 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;