On Fri, Mar 13, 2015 at 11:55:07AM +0530, Archit Taneja wrote:
On 03/11/2015 08:47 PM, Daniel Vetter wrote:
On Wed, Mar 11, 2015 at 01:51:02PM +0530, Archit Taneja wrote:
On 03/10/2015 05:47 PM, Daniel Vetter wrote:
On Tue, Mar 10, 2015 at 03:52:41PM +0530, Archit Taneja wrote:
On 03/10/2015 03:35 PM, Daniel Vetter wrote:
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: >>>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.
I was trying that out. Removing DRM_KMS_FB_HELPER and having DRM_FBDEV_EMULATION disabled breaks drivers which use FB stuff internally in their respective xyz_fbdev.c files.
But with the stubbed out functions that should work, right? Why doesn't it?
There are still calls to functions from fb core like fb_set_suspend and register_framebuffer which aren't covered by the drm fb helper functions.
Hm, sounds like we need another patch to stub out fb_set_suspend when fbdev isn't enabled. Is there anything else?
There are a handful of fb core functions which are called by drm drivers:
fb_alloc_cmap/fb_dealloc_cmap
fb_sys_read/fb_sys_write
register_framebuffer/unregister_framebuffer/unlink_framebuffer/ remove_conflicting_framebuffers
fb_set_suspend
fb_deferred_io_init/fb_deferred_io_cleanup
framebuffer_alloc/framebuffer_release
Hm yeah that's somewhat annoying indeed. What about the following: 1. We move all the #include <linux/fb.h> from drivers into drm_fb_helper.h
2. Then we add stubs for these functions in drm_fb_helper.h, like this
#if defined(CONFIG_FB) #include <linux/fb.h> #else
/* static inline stubs for all the fb stuff used by kms drivers */ #endif
Imo this makes sense since kms drivers really have a bit a special situation with fbdev. They're not full-blown fbdev drivers and can be useful fully without fbdev.
What do you think? -Daniel