On Tue, Mar 10, 2015 at 03:22:49PM +0530, Archit Taneja wrote: > > > On 03/10/2015 03:17 PM, Daniel Vetter wrote: > >On Tue, Mar 10, 2015 at 03:11:28PM +0530, Archit Taneja wrote: > >>Legacy fbdev emulation support via DRM is achieved through KMS FB helpers. > >>Most modesetting drivers enable provide fbdev emulation by default by > >>selecting > >>KMS FB helpers. A few provide a separate Kconfig option for the user to > >>enable > >>or disbale fbdev emulation. > >> > >>Enabling fbdev emulation is finally a distro-level decision. Having a top > >>level > >>Kconfig option for fbdev emulation helps by providing a uniform way to > >>enable/disable fbdev emulation for any modesetting driver. It also lets us > >>remove unnecessary driver specific Kconfig options that causes bloat. > >> > >>With a top level Kconfig in place, we can stub out the fb helper functions > >>when > >>not needed without breaking functionality. Having stub functions also > >>prevents > >>drivers to require wrapping fb helper function calls with #ifdefs. > >> > >>DRM_FBDEV_EMULATION defaults to y since many drivers enable fbdev emulation > >>by > >>default and majority of distributions expect the fbdev interface in the > >>kernel. > >> > >>For now, this config selects both FB_SYS_* and FB_CFB_* configs as some > >>modesetting drivers use the former and other the later. This needs to be > >>taken > >>care of in a better way. > >> > >>Signed-off-by: Archit Taneja <arch...@codeaurora.org> > >>--- > >> drivers/gpu/drm/Kconfig | 18 +++++++ > >> drivers/gpu/drm/Makefile | 4 ++ > >> include/drm/drm_fb_helper.h | 120 > >> ++++++++++++++++++++++++++++++++++++++++++++ > >> 3 files changed, 142 insertions(+) > >> > >>diff --git a/drivers/gpu/drm/Kconfig b/drivers/gpu/drm/Kconfig > >>index 151a050..38f83a0 100644 > >>--- a/drivers/gpu/drm/Kconfig > >>+++ b/drivers/gpu/drm/Kconfig > >>@@ -40,6 +40,24 @@ config DRM_KMS_FB_HELPER > >> help > >> FBDEV helpers for KMS drivers. > >> > >>+config DRM_FBDEV_EMULATION > >>+ bool "Enable legacy fbdev support for your modesetting driver" > >>+ depends on DRM > >>+ select DRM_KMS_HELPER > >>+ select DRM_KMS_FB_HELPER > >>+ select FB_SYS_FILLRECT > >>+ select FB_SYS_COPYAREA > >>+ select FB_SYS_IMAGEBLIT > >>+ select FB_SYS_FOPS > >>+ select FB_CFB_FILLRECT > >>+ select FB_CFB_COPYAREA > >>+ select FB_CFB_IMAGEBLIT > >>+ default y > >>+ help > >>+ Choose this option if you have a need for the legacy fbdev > >>+ support. Note that this support also provide the linux console > >>+ support on top of your modesetting driver. > > > >Maybe clarify that for linux console support you also need > >CONFIG_FRAMEBUFFER_CONSOLE? fbdev alone isn't enough. > > DRM_KMS_FB_HELPER selects that for us, right?
Hm right I've missed that. Reminds me that you need one more patch at the end to remove all the various select DRM_KMS_FB_HELPER from all drm drivers. Otherwise this knob here won't work by default if you e.g. select radeon. In general we can't mix explicit options with menu entries with a select. -Daniel -- Daniel Vetter Software Engineer, Intel Corporation +41 (0) 79 365 57 48 - http://blog.ffwll.ch -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
