From: Mark Jackson <mpfj-list@mimc.co.uk>
Subject: [RFC] Setting default virtual fb geometry
Date: Wed, 12 Aug 2009 09:59:54 +0100
Message-ID: <4A82848A.6020108@mimc.co.uk>
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Errors-To: linux-fbdev-devel-bounces@lists.sourceforge.net
To: linux-fbdev-devel@lists.sourceforge.net

At the moment you can set fbmem from the kernel bootargs, and
xres / yres are usually setup in the board init files.

However, there doesn;t seem to be any simple way to specify
the virtual size of the display (eg. for double buffering).

I have "hacked" the Atmel display driver in a quick and dirty
way to fulfil my needs, but I guess it needs a more formal
approach.

Anyone care to comment on how this "issue" might be resolved ?

Regards
Mark
---
 drivers/video/atmel_lcdfb.c |    5 +++++
 1 files changed, 5 insertions(+), 0 deletions(-)

diff --git a/drivers/video/atmel_lcdfb.c b/drivers/video/atmel_lcdfb.c
index 2864e05..54df737 100644
--- a/drivers/video/atmel_lcdfb.c
+++ b/drivers/video/atmel_lcdfb.c
@@ -353,6 +353,11 @@ static int atmel_lcdfb_check_var(struct fb_var_screeninfo *var,
 		return -EINVAL;
 	}
 
+	/* Calculate virtual yres based on fbmem size */
+	var->yres_virtual = info->fix.smem_len /
+				(var->xres * var->yres * (var->bits_per_pixel / 8));
+	var->yres_virtual *= var->yres;
+
 	/* Do not allow to have real resoulution larger than virtual */
 	if (var->xres > var->xres_virtual)
 		var->xres_virtual = var->xres;

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