Hi,
On 03/13/2015 02:36 PM, Daniel Vetter wrote:
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:
We move all the #include <linux/fb.h> from drivers into drm_fb_helper.h
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.
I was trying this out. Removing 'linux/fb.h' and replacing stub fb funcs won't really work because struct declarations(like fb_info) also get removed.
I considered placing '#if IS_ENABLED(CONFIG_FB)' within linux/fb.h itself, but that seemed a bit too intrusive.
This is what I'm currently doing:
- Some funcs, like framebufer_alloc/release, alloc_cmap/dealloc_cmap would actually benefit if we have drm fb helpers for them. They are used in exactly the same manner by all the drivers.
- For the rest of the functions that are sparsely used, I was considering making very simple drm_fb_* wrapper functions. Something like:
void drm_fb_helper_deferred_io_init(struct drm_fb_helper *helper) { if (helper->fbdev) fb_deferred_io_init(helper->fbdev); }
We could have all fb calls called within drm_fb_helper.c, creating drm_fb_helper_* stub functions would then be an easier task. What do you think?
Archit