atmel_lcdfb: LCDC startup fix

From: Anti Sullin <[email protected]>

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).

@@ -268,6 +268,10 @@
 	/* 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)

-------------------------------------------------------------------------
This SF.net email is sponsored by: Microsoft Defy all challenges. Microsoft(R) Visual Studio 2005.
http://clk.atdmt.com/MRT/go/vse0120000070mrt/direct/01/