lkml.org 
[lkml]   [2015]   [Feb]   [14]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
/
Date
From
SubjectRe: [PATCH 5/8] fbdev: ssd1307fb: Add module parameter bitsperpixel.
On Sat, Feb 07, 2015 at 05:05:03PM +0100, Thomas Niederprüm wrote:
> Am Sat, 7 Feb 2015 12:20:43 +0100
> schrieb Maxime Ripard <maxime.ripard@free-electrons.com>:
>
> > On Fri, Feb 06, 2015 at 11:28:11PM +0100, niederp@physik.uni-kl.de
> > wrote:
> > > From: Thomas Niederprüm <niederp@physik.uni-kl.de>
> > >
> > > This patch adds a module parameter 'bitsperpixel' to adjust the
> > > colordepth of the framebuffer. All values >1 will result in memory
> > > map of the requested color depth. However only the MSB of each
> > > pixel will be sent to the device. The framebuffer identifies itself
> > > as a grayscale display with the specified depth.
> >
> > I'm not sure this is the right thing to do.
> >
> > The bits per pixel for this display is rightfully defined, used and
> > reported to the userspace, why would you want to change that?
>
> You are right of course. The display is 1bpp and it reports to be 1
> bpp. The problem is that there is almost no userspace library that can
> handle 1 bit framebuffers correctly. So it is nice if the framebuffer
> (optionally) can expose itself as 8 bits per pixel grayscale to the
> userspace program. As an example this allows to run DirectFB on the
> framebuffer, which is not possible out of the box for 1bpp.
>
> Also note that if do not set the module parameter at load time
> the framebuffer will be 1bpp. So you have to actively set that module
> parameter to make the framebuffer pretend to be more than 1bpp.
>
> In any case I don't cling to that patch, I just thought it was a nice
> feature.

I'd say that the right fix would be to patch DirectFB, instead of
faking that in the kernel.

But again, that's probably Tomi's call, not mine.

Maxime

--
Maxime Ripard, Free Electrons
Embedded Linux, Kernel and Android engineering
http://free-electrons.com
[unhandled content-type:application/pgp-signature]
\
 
 \ /
  Last update: 2015-02-14 17:01    [W:0.119 / U:3.192 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site