On Mon, Jul 13, 2015 at 12:12:06PM +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.
>
> Signed-off-by: Archit Taneja <architt@xxxxxxxxxxxxxx>
> ---
> drivers/gpu/drm/Kconfig | 12 +++
> drivers/gpu/drm/Makefile | 2 +-
> include/drm/drm_fb_helper.h | 192 ++++++++++++++++++++++++++++++++++++++++++++
> 3 files changed, 205 insertions(+), 1 deletion(-)
>
> diff --git a/drivers/gpu/drm/Kconfig b/drivers/gpu/drm/Kconfig
> index e373f8a..8fd670b 100644
> --- a/drivers/gpu/drm/Kconfig
> +++ b/drivers/gpu/drm/Kconfig
> @@ -47,6 +47,18 @@ 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
> + 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. You'd need this if
> + you're looking for console support too.
Maybe add an "If unsure say Y." here.
> +
> config DRM_LOAD_EDID_FIRMWARE
> bool "Allow to specify an EDID data set instead of probing for it"
> depends on DRM_KMS_HELPER
> diff --git a/drivers/gpu/drm/Makefile b/drivers/gpu/drm/Makefile
> index 5713d05..8858510 100644
> --- a/drivers/gpu/drm/Makefile
> +++ b/drivers/gpu/drm/Makefile
> @@ -23,7 +23,7 @@ drm-$(CONFIG_OF) += drm_of.o
> drm_kms_helper-y := drm_crtc_helper.o drm_dp_helper.o drm_probe_helper.o \
> drm_plane_helper.o drm_dp_mst_topology.o drm_atomic_helper.o
> drm_kms_helper-$(CONFIG_DRM_LOAD_EDID_FIRMWARE) += drm_edid_load.o
> -drm_kms_helper-$(CONFIG_DRM_KMS_FB_HELPER) += drm_fb_helper.o
> +drm_kms_helper-$(CONFIG_DRM_FBDEV_EMULATION) += drm_fb_helper.o
> drm_kms_helper-$(CONFIG_DRM_KMS_CMA_HELPER) += drm_fb_cma_helper.o
>
> obj-$(CONFIG_DRM_KMS_HELPER) += drm_kms_helper.o
> diff --git a/include/drm/drm_fb_helper.h b/include/drm/drm_fb_helper.h
> index cc19e88..8f972da 100644
> --- a/include/drm/drm_fb_helper.h
> +++ b/include/drm/drm_fb_helper.h
> @@ -122,6 +122,7 @@ struct drm_fb_helper {
> bool delayed_hotplug;
> };
>
> +#ifdef CONFIG_DRM_FBDEV_EMULATION
> void drm_fb_helper_prepare(struct drm_device *dev, struct drm_fb_helper *helper,
> const struct drm_fb_helper_funcs *funcs);
> int drm_fb_helper_init(struct drm_device *dev,
> @@ -188,4 +189,195 @@ drm_pick_cmdline_mode(struct drm_fb_helper_connector *fb_helper_conn,
> int drm_fb_helper_add_one_connector(struct drm_fb_helper *fb_helper, struct drm_connector *connector);
> int drm_fb_helper_remove_one_connector(struct drm_fb_helper *fb_helper,
> struct drm_connector *connector);
> +#else
> +static inline void drm_fb_helper_prepare(struct drm_device *dev,
> + struct drm_fb_helper *helper,
> + const struct drm_fb_helper_funcs *funcs)
> +{
> +}
> +
> +static inline int drm_fb_helper_init(struct drm_device *dev,
> + struct drm_fb_helper *helper, int crtc_count,
> + int max_conn)
> +{
> + return 0;
> +}
> +
> +static inline void drm_fb_helper_fini(struct drm_fb_helper *helper)
> +{
> +}
> +
> +static inline int drm_fb_helper_blank(int blank, struct fb_info *info)
> +{
> + return 0;
> +}
> +
> +static inline int drm_fb_helper_pan_display(struct fb_var_screeninfo *var,
> + struct fb_info *info)
> +{
> + return 0;
> +}
> +
> +static inline int drm_fb_helper_set_par(struct fb_info *info)
> +{
> + return 0;
> +}
> +
> +static inline int drm_fb_helper_check_var(struct fb_var_screeninfo *var,
> + struct fb_info *info)
> +{
> + return 0;
> +}
> +
> +static inline bool
> +drm_fb_helper_restore_fbdev_mode_unlocked(struct drm_fb_helper *fb_helper)
> +{
> + return true;
> +}
> +
> +static inline struct fb_info *
> +drm_fb_helper_alloc_fbi(struct drm_fb_helper *fb_helper)
> +{
> + return NULL;
> +}
> +
> +static inline void drm_fb_helper_unregister_fbi(struct drm_fb_helper *fb_helper)
> +{
> +}
> +static inline void drm_fb_helper_release_fbi(struct drm_fb_helper *fb_helper)
> +{
> +}
> +
> +static inline void drm_fb_helper_fill_var(struct fb_info *info,
> + struct drm_fb_helper *fb_helper,
> + uint32_t fb_width, uint32_t fb_height)
> +{
> +}
> +
> +static inline void drm_fb_helper_fill_fix(struct fb_info *info, uint32_t pitch,
> + uint32_t depth)
> +{
> +}
> +
> +static inline int drm_fb_helper_setcmap(struct fb_cmap *cmap,
> + struct fb_info *info)
> +{
> + return 0;
> +}
> +
> +static inline void drm_fb_helper_unlink_fbi(struct drm_fb_helper *fb_helper)
> +{
> +}
> +
> +static inline ssize_t drm_fb_helper_sys_read(struct fb_info *info,
> + char __user *buf, size_t count,
> + loff_t *ppos)
> +{
> + return -ENODEV;
> +}
> +
> +static inline ssize_t drm_fb_helper_sys_write(struct fb_info *info,
> + const char __user *buf, size_t count,
> + loff_t *ppos)
> +{
> + return -ENODEV;
> +}
> +
> +static inline void drm_fb_helper_sys_fillrect(struct fb_info *info,
> + const struct fb_fillrect *rect)
> +{
> +}
> +
> +static inline void drm_fb_helper_sys_copyarea(struct fb_info *info,
> + const struct fb_copyarea *area)
> +{
> +}
> +
> +static inline void drm_fb_helper_sys_imageblit(struct fb_info *info,
> + const struct fb_image *image)
> +{
> +}
> +
> +static inline void drm_fb_helper_cfb_fillrect(struct fb_info *info,
> + const struct fb_fillrect *rect)
> +{
> +}
> +
> +static inline void drm_fb_helper_cfb_copyarea(struct fb_info *info,
> + const struct fb_copyarea *area)
> +{
> +}
> +
> +static inline void drm_fb_helper_cfb_imageblit(struct fb_info *info,
> + const struct fb_image *image)
> +{
> +}
> +
> +static inline void drm_fb_helper_set_suspend(struct drm_fb_helper *fb_helper,
> + int state)
> +{
> +}
> +
> +static inline int
> +drm_fb_helper_remove_conflicting_framebuffers(struct apertures_struct *a,
> + const char *name, bool primary)
> +{
> + return 0;
> +}
The above dummy functions don't exist yet - is this part of a more
extensive patch series to introduce those as drm fb helpers too? Should
probably be dropped for now.
-Daniel
> +
> +static inline int drm_fb_helper_hotplug_event(struct drm_fb_helper *fb_helper)
> +{
> + return 0;
> +}
> +
> +static inline int drm_fb_helper_initial_config(struct drm_fb_helper *fb_helper,
> + int bpp_sel)
> +{
> + return 0;
> +}
> +
> +static inline int
> +drm_fb_helper_single_add_all_connectors(struct drm_fb_helper *fb_helper)
> +{
> + return 0;
> +}
> +
> +static inline int drm_fb_helper_debug_enter(struct fb_info *info)
> +{
> + return 0;
> +}
> +
> +static inline int drm_fb_helper_debug_leave(struct fb_info *info)
> +{
> + return 0;
> +}
> +
> +static inline struct drm_display_mode *
> +drm_has_preferred_mode(struct drm_fb_helper_connector *fb_connector,
> + int width, int height)
> +{
> + return NULL;
> +}
> +
> +static inline struct drm_display_mode *
> +drm_pick_cmdline_mode(struct drm_fb_helper_connector *fb_helper_conn,
> + int width, int height)
> +{
> + return NULL;
> +}
> +
> +static inline int
> +drm_fb_helper_add_one_connector(struct drm_fb_helper *fb_helper,
> + struct drm_connector *connector)
> +{
> + return 0;
> +}
> +
> +static inline int
> +drm_fb_helper_remove_one_connector(struct drm_fb_helper *fb_helper,
> + struct drm_connector *connector)
> +{
> + return 0;
> +}
> +#endif
> #endif
> --
> The Qualcomm Innovation Center, Inc. is a member of the Code Aurora Forum,
> hosted by The Linux Foundation
>
--
Daniel Vetter
Software Engineer, Intel Corporation
http://blog.ffwll.ch
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