On 14/02/15 17:54, Maxime Ripard wrote: > 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 : >> >>> On Fri, Feb 06, 2015 at 11:28:11PM +0100, niederp@physik.uni-kl.de >>> wrote: >>>> From: Thomas Niederprüm >>>> >>>> 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. Right, I'm not thrilled =). I don't think it's a good idea to lie to the userspace (except when fixing regressions). Tomi