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authorAnti Sullin <anti.sullin@artecdesign.ee>2007-11-28 16:21:40 -0800
committerLinus Torvalds <torvalds@woody.linux-foundation.org>2007-11-29 09:24:53 -0800
commite593f070b40887dc0415646a4c0720eb8630c722 (patch)
tree15c7213d85f345602b5a67d7e71c4416b649e6e7 /drivers/video/atmel_lcdfb.c
parent2868f89fc43d16441a90714d4676089bdfc4255a (diff)
atmel_lcdfb: LCDC startup fix
This patch adds an additional loop, that delays turning off the DMA until the LCDC core has been turned off. This prevents the picture to be shifted some random length when the kernel re-initializes the LCDC. Without this patch, the LCDC keeps running for some small time after the PWRCON:LCD_PWR has been cleared ; the FIFO suffers an underrun and on re-starting the LCDC the FIFO data stays shifted. This behavior has been seen and fixed on AT91SAM9261-EK and two custom AT91SAM9261 boards, all of them having different LCD panels. Thanks a lot to Anti Sullin for submitting this patch (long time ago). Signed-off-by: Anti Sullin <anti.sullin@artecdesign.ee> Signed-off-by: Andrew Victor <andrew@sanpeople.com> Signed-off-by: Nicolas Ferre <nicolas.ferre@atmel.com> Acked-by: Haavard Skinnemoen <hskinnemoen@atmel.com> Cc: "Antonino A. Daplas" <adaplas@pol.net> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'drivers/video/atmel_lcdfb.c')
-rw-r--r--drivers/video/atmel_lcdfb.c4
1 files changed, 4 insertions, 0 deletions
diff --git a/drivers/video/atmel_lcdfb.c b/drivers/video/atmel_lcdfb.c
index 235b618b411..11a3a222dfc 100644
--- a/drivers/video/atmel_lcdfb.c
+++ b/drivers/video/atmel_lcdfb.c
@@ -268,6 +268,10 @@ static int atmel_lcdfb_set_par(struct fb_info *info)
/* Turn off the LCD controller and the DMA controller */
lcdc_writel(sinfo, ATMEL_LCDC_PWRCON, sinfo->guard_time << ATMEL_LCDC_GUARDT_OFFSET);
+ /* Wait for the LCDC core to become idle */
+ while (lcdc_readl(sinfo, ATMEL_LCDC_PWRCON) & ATMEL_LCDC_BUSY)
+ msleep(10);
+
lcdc_writel(sinfo, ATMEL_LCDC_DMACON, 0);
if (info->var.bits_per_pixel == 1)