From: dhylands@gmail.com (Dave Hylands)
To: kernelnewbies@lists.kernelnewbies.org
Subject: Double buffer support in Framebuffer?
Date: Wed, 27 Apr 2011 20:22:48 -0700 [thread overview]
Message-ID: <BANLkTim32cbFJq_F3G=OSnPMCNyqzTz9rQ@mail.gmail.com> (raw)
In-Reply-To: <BANLkTi=EaY-3NR+-w0HNnFkHVi7xwyZB=w@mail.gmail.com>
Hi Philip,
Replying to all this time.
On Wed, Apr 27, 2011 at 4:24 PM, siqiao chen <siqiaochen@gmail.com> wrote:
> Hello, Could I ask how do I enable double buffer support in FrameBuffer
> device?
> I think I could manually increase xres_virtual/yres_virtual to 2 times of
> the display size in video driver and swap xoffset/yoffset after VSync. But
> could I know if this is the right way to do double buffering or this
> function is already built-in?
You're on the right track. You only need to double xres_virtual or
yres_virtual, not both.
Let's suppose that your display is 800x480. Then your display driver
needs to size the framebuffer to be 800x960, and you'd use
FBIOPAN_DISPLAY to toggle between 0,0 and 0,480.
The driver has to support the double sized framebuffer and the pan
command (or maybe you can modify yoffset directly? I haven't tried
this approach myself).
--
Dave Hylands
Shuswap, BC, Canada
http://www.davehylands.com
next prev parent reply other threads:[~2011-04-28 3:22 UTC|newest]
Thread overview: 3+ messages / expand[flat|nested] mbox.gz Atom feed top
2011-04-27 23:24 Double buffer support in Framebuffer? siqiao chen
2011-04-28 3:22 ` Dave Hylands [this message]
2011-04-28 4:47 ` siqiao chen
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