video: atmel_hlcdfb: enable dcache support

To support dcache, we need flush DMA descriptor buffer before enable lcd
DMA.

Also we need call lcd_set_flush_dcache(1) to make lcd driver flush the
lcd buffer if there is any change.

Cc: Anatolij Gustschin <agust@denx.de>
Signed-off-by: Josh Wu <josh.wu@atmel.com>
Acked-by: Anatolij Gustschin <agust@denx.de>
Signed-off-by: Andreas Bießmann <andreas.devel@googlemail.com>

drivers/video/atmel_hlcdfb.c

@@ -171,6 +171,9 @@ void lcd_ctrl_init(void *lcdbase)
 			| LCDC_BASECTRL_DMAIEN | LCDC_BASECTRL_DFETCH;
 	desc->next = (u32)desc;
 
+	/* Flush the DMA descriptor if we enabled dcache */
+	flush_dcache_range((u32)desc, (u32)desc + sizeof(*desc));
+
 	lcdc_writel(&regs->lcdc_baseaddr, desc->address);
 	lcdc_writel(&regs->lcdc_basectrl, desc->control);
 	lcdc_writel(&regs->lcdc_basenext, desc->next);
@@ -194,4 +197,7 @@ void lcd_ctrl_init(void *lcdbase)
 	lcdc_writel(&regs->lcdc_lcden, value | LCDC_LCDEN_PWMEN);
 	while (!(lcdc_readl(&regs->lcdc_lcdsr) & LCDC_LCDSR_PWMSTS))
 		udelay(1);
+
+	/* Enable flushing if we enabled dcache */
+	lcd_set_flush_dcache(1);
 }