Am Tue, 10 Mar 2015 12:45:49 +0200 schrieb Tomi Valkeinen <tomi.valkeinen@xxxxxx>: > 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 <maxime.ripard@xxxxxxxxxxxxxxxxxx>: > >> > >>> On Fri, Feb 06, 2015 at 11:28:11PM +0100, niederp@xxxxxxxxxxxxxxxx > >>> wrote: > >>>> From: Thomas Niederprüm <niederp@xxxxxxxxxxxxxxxx> > >>>> > >>>> 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). Ok, since Maxime and you agree that this is not desirable I will drop that patch in v4. Thomas -- To unsubscribe from this list: send the line "unsubscribe linux-fbdev" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
