atmel_lcdfb: add board parameter specify framebuffer memory size

Specify how much physically continuous, DMA capable memory will be
allocated at driver initialization time.  This allow to create framebuffer
device with larger virtual resolution.  Combine with y-panning this can be
used to implement double buffering acceleration method.

Signed-off-by: Stanislaw Gruszka <stf_xl@wp.pl>
Acked-by: Haavard Skinnemoen <haavard.skinnemoen@atmel.com>
Acked-by: Krzysztof Helt <krzysztof.h1@wp.pl>
Cc: Nicolas Ferre <nicolas.ferre@atmel.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

drivers/video/atmel_lcdfb.c

@@ -242,9 +242,11 @@ static int atmel_lcdfb_alloc_video_memory(struct atmel_lcdfb_info *sinfo)
 {
 	struct fb_info *info = sinfo->info;
 	struct fb_var_screeninfo *var = &info->var;
+	unsigned int smem_len;
 
-	info->fix.smem_len = (var->xres_virtual * var->yres_virtual
-			    * ((var->bits_per_pixel + 7) / 8));
+	smem_len = (var->xres_virtual * var->yres_virtual
+		    * ((var->bits_per_pixel + 7) / 8));
+	info->fix.smem_len = max(smem_len, sinfo->smem_len);
 
 	info->screen_base = dma_alloc_writecombine(info->device, info->fix.smem_len,
 					(dma_addr_t *)&info->fix.smem_start, GFP_KERNEL);
@@ -796,6 +798,7 @@ static int __init atmel_lcdfb_probe(struct platform_device *pdev)
 		sinfo->default_monspecs = pdata_sinfo->default_monspecs;
 		sinfo->atmel_lcdfb_power_control = pdata_sinfo->atmel_lcdfb_power_control;
 		sinfo->guard_time = pdata_sinfo->guard_time;
+		sinfo->smem_len = pdata_sinfo->smem_len;
 		sinfo->lcdcon_is_backlight = pdata_sinfo->lcdcon_is_backlight;
 		sinfo->lcd_wiring_mode = pdata_sinfo->lcd_wiring_mode;
 	} else {

include/video/atmel_lcdc.h

@@ -41,6 +41,7 @@ struct atmel_lcdfb_info {
 	struct work_struct	task;
 
 	unsigned int		guard_time;
+	unsigned int 		smem_len;
 	struct platform_device	*pdev;
 	struct clk		*bus_clk;
 	struct clk		*lcdc_clk;