From e593f070b40887dc0415646a4c0720eb8630c722 Mon Sep 17 00:00:00 2001 From: Anti Sullin Date: Wed, 28 Nov 2007 16:21:40 -0800 Subject: [PATCH] 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 Signed-off-by: Andrew Victor Signed-off-by: Nicolas Ferre Acked-by: Haavard Skinnemoen Cc: "Antonino A. Daplas" Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- drivers/video/atmel_lcdfb.c | 4 ++++ 1 file changed, 4 insertions(+) diff --git a/drivers/video/atmel_lcdfb.c b/drivers/video/atmel_lcdfb.c index 235b618b41..11a3a222df 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) -- 2.39.5