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[v4,00/13] drm/fbdev: Remove DRM's helpers for fbdev I/O

Message ID 20230524092150.11776-1-tzimmermann@suse.de
Headers show
Series drm/fbdev: Remove DRM's helpers for fbdev I/O | expand

Message

Thomas Zimmermann May 24, 2023, 9:21 a.m. UTC
DRM provides a number of wrappers around fbdev cfb_() sys_(), fb_io_()
and fb_sys_() helpers. The DRM functions don't provide any additional
functionality for most DRM drivers. So remove them and call the fbdev
I/O helpers directly.

The DRM fbdev I/O wrappers were originally added because <linux/fb.h>
does not protect its content with CONFIG_FB. DRM fbdev emulation did
not build if the config option had been disabled. This has been
fixed. For fbdev-generic and i915, the wrappers added support for damage
handling. But this is better handled within the two callers, as each
is special in its damage handling.

Patch 1 adds several internal Kconfig options that DRM drivers (and
possibly other fbdev code) will use to select the correct set of I/O
helpers. Patch 2 adds initializers for struct fb_ops and generator
macros for the callback functions. These macros will simplify drivers.
This patchset applies the new options and macros to DRM fbdev emulation,
but regular fbdev drivers can use them as well.

Patches 3 to 10 replace the DRM wrappers in a number of fbdev emulations.
Patch 10 exports two helpers for damage handling. Patches 12 and 13
update fbdev-generic and i915 with the help of the exported functions.
The patches also remove DRM's fbdev I/O helpers, which are now unused.

DRM's fbdev helpers had to select fbdev I/O helpers for I/O and for
system memory. Each fbdev emulation now selects the correct helpers
for itself. Depending on the selected DRM drivers, kernel builds will
now only contain the necessary fbdev I/O helpers and might be slightly
smaller in size.

v4:
	* use initializer and generator macros for struct fb_ops
	* partially support damage handling in msm (Dmitri)
v3:
	* fix Kconfig options (Jingfeng)
	* minimize changes to exynos (Sam)
v2:
	* simplify Kconfig handling (Sam)

Thomas Zimmermann (13):
  fbdev: Add Kconfig options to select different fb_ops helpers
  fbdev: Add initializer macros for struct fb_ops
  drm/armada: Use regular fbdev I/O helpers
  drm/exynos: Use regular fbdev I/O helpers
  drm/gma500: Use regular fbdev I/O helpers
  drm/radeon: Use regular fbdev I/O helpers
  drm/fbdev-dma: Use regular fbdev I/O helpers
  drm/msm: Use regular fbdev I/O helpers
  drm/omapdrm: Use regular fbdev I/O helpers
  drm/tegra: Use regular fbdev I/O helpers
  drm/fb-helper: Export helpers for marking damage areas
  drm/fbdev-generic: Implement dedicated fbdev I/O helpers
  drm/i915: Implement dedicated fbdev I/O helpers

 drivers/gpu/drm/Kconfig                    |  10 +-
 drivers/gpu/drm/armada/Kconfig             |   1 +
 drivers/gpu/drm/armada/armada_fbdev.c      |   7 +-
 drivers/gpu/drm/drm_fb_helper.c            | 236 ++-------------------
 drivers/gpu/drm/drm_fbdev_dma.c            |  11 +-
 drivers/gpu/drm/drm_fbdev_generic.c        |  11 +-
 drivers/gpu/drm/exynos/Kconfig             |   1 +
 drivers/gpu/drm/exynos/exynos_drm_fbdev.c  |   9 +-
 drivers/gpu/drm/gma500/Kconfig             |   1 +
 drivers/gpu/drm/gma500/fbdev.c             |   8 +-
 drivers/gpu/drm/i915/Kconfig               |   1 +
 drivers/gpu/drm/i915/display/intel_fbdev.c |  14 +-
 drivers/gpu/drm/msm/Kconfig                |   1 +
 drivers/gpu/drm/msm/msm_fbdev.c            |  17 +-
 drivers/gpu/drm/omapdrm/Kconfig            |   1 +
 drivers/gpu/drm/omapdrm/omap_fbdev.c       |  11 +-
 drivers/gpu/drm/radeon/Kconfig             |   1 +
 drivers/gpu/drm/radeon/radeon_fbdev.c      |   9 +-
 drivers/gpu/drm/tegra/Kconfig              |   1 +
 drivers/gpu/drm/tegra/fbdev.c              |   8 +-
 drivers/video/fbdev/Kconfig                |  21 ++
 include/drm/drm_fb_helper.h                |  83 +-------
 include/linux/fb.h                         | 112 ++++++++++
 23 files changed, 212 insertions(+), 363 deletions(-)


base-commit: 216281f91018b24567e59ae46ce7e96fb92063cf
prerequisite-patch-id: 0aa359f6144c4015c140c8a6750be19099c676fb
prerequisite-patch-id: c67e5d886a47b7d0266d81100837557fda34cb24
prerequisite-patch-id: cbc453ee02fae02af22fbfdce56ab732c7a88c36
prerequisite-patch-id: 8bff2b12862e44027a25837ea7510f633d40839e
prerequisite-patch-id: 97ac107455aff4e0ec039d166ecdd2430d20f22e

Comments

Thomas Zimmermann May 30, 2023, 7:12 a.m. UTC | #1
Hi

Am 29.05.23 um 21:36 schrieb Sam Ravnborg:
> Hi Thomas,
> 
> On Wed, May 24, 2023 at 11:21:50AM +0200, Thomas Zimmermann wrote:
>> Implement dedicated fbdev helpers for framebuffer I/O instead
>> of using DRM's helpers. Use an fbdev generator macro for
>> deferred I/O to create the fbdev callbacks. i915 was the only
>> caller of the DRM helpers, so remove them from the helper module.
>>
>> i915's fbdev emulation is still incomplete as it doesn't implement
>> deferred I/O and damage handling for mmaped pages.
>>
>> v4:
>> 	* generate deferred-I/O helpers
>> 	* use initializer macros for fb_ops
>> v2:
>> 	* use FB_IO_HELPERS options
>>
>> Signed-off-by: Thomas Zimmermann <tzimmermann@suse.de>
>> Cc: Jani Nikula <jani.nikula@linux.intel.com>
>> Cc: Joonas Lahtinen <joonas.lahtinen@linux.intel.com>
>> Cc: Rodrigo Vivi <rodrigo.vivi@intel.com>
>> Cc: Tvrtko Ursulin <tvrtko.ursulin@linux.intel.com>
>> Cc: "Ville Syrjälä" <ville.syrjala@linux.intel.com>
>> ---
>>   drivers/gpu/drm/Kconfig                    |   3 -
>>   drivers/gpu/drm/drm_fb_helper.c            | 107 ---------------------
>>   drivers/gpu/drm/i915/Kconfig               |   1 +
>>   drivers/gpu/drm/i915/display/intel_fbdev.c |  14 +--
>>   include/drm/drm_fb_helper.h                |  39 --------
>>   5 files changed, 9 insertions(+), 155 deletions(-)
>>
>> diff --git a/drivers/gpu/drm/Kconfig b/drivers/gpu/drm/Kconfig
>> index 92a782827b7b..bb2e48cc6cd6 100644
>> --- a/drivers/gpu/drm/Kconfig
>> +++ b/drivers/gpu/drm/Kconfig
>> @@ -133,9 +133,6 @@ config DRM_FBDEV_EMULATION
>>   	bool "Enable legacy fbdev support for your modesetting driver"
>>   	depends on DRM_KMS_HELPER
>>   	depends on FB=y || FB=DRM_KMS_HELPER
>> -	select FB_CFB_FILLRECT
>> -	select FB_CFB_COPYAREA
>> -	select FB_CFB_IMAGEBLIT
>>   	select FRAMEBUFFER_CONSOLE if !EXPERT
>>   	select FRAMEBUFFER_CONSOLE_DETECT_PRIMARY if FRAMEBUFFER_CONSOLE
>>   	default y
>> diff --git a/drivers/gpu/drm/drm_fb_helper.c b/drivers/gpu/drm/drm_fb_helper.c
>> index bab6b252f02a..9978147bbc8a 100644
>> --- a/drivers/gpu/drm/drm_fb_helper.c
>> +++ b/drivers/gpu/drm/drm_fb_helper.c
>> @@ -736,113 +736,6 @@ void drm_fb_helper_deferred_io(struct fb_info *info, struct list_head *pagerefli
>>   }
>>   EXPORT_SYMBOL(drm_fb_helper_deferred_io);
>>   
>> -/**
>> - * drm_fb_helper_cfb_read - Implements struct &fb_ops.fb_read for I/O memory
>> - * @info: fb_info struct pointer
>> - * @buf: userspace buffer to read from framebuffer memory
>> - * @count: number of bytes to read from framebuffer memory
>> - * @ppos: read offset within framebuffer memory
>> - *
>> - * Returns:
>> - * The number of bytes read on success, or an error code otherwise.
>> - */
>> -ssize_t drm_fb_helper_cfb_read(struct fb_info *info, char __user *buf,
>> -			       size_t count, loff_t *ppos)
>> -{
>> -	return fb_io_read(info, buf, count, ppos);
>> -}
>> -EXPORT_SYMBOL(drm_fb_helper_cfb_read);
>> -
>> -/**
>> - * drm_fb_helper_cfb_write - Implements struct &fb_ops.fb_write for I/O memory
>> - * @info: fb_info struct pointer
>> - * @buf: userspace buffer to write to framebuffer memory
>> - * @count: number of bytes to write to framebuffer memory
>> - * @ppos: write offset within framebuffer memory
>> - *
>> - * Returns:
>> - * The number of bytes written on success, or an error code otherwise.
>> - */
>> -ssize_t drm_fb_helper_cfb_write(struct fb_info *info, const char __user *buf,
>> -				size_t count, loff_t *ppos)
>> -{
>> -	struct drm_fb_helper *helper = info->par;
>> -	loff_t pos = *ppos;
>> -	ssize_t ret;
>> -	struct drm_rect damage_area;
>> -
>> -	ret = fb_io_write(info, buf, count, ppos);
>> -	if (ret <= 0)
>> -		return ret;
>> -
>> -	if (helper->funcs->fb_dirty) {
>> -		drm_fb_helper_memory_range_to_clip(info, pos, ret, &damage_area);
>> -		drm_fb_helper_damage(helper, damage_area.x1, damage_area.y1,
>> -				     drm_rect_width(&damage_area),
>> -				     drm_rect_height(&damage_area));
>> -	}
> 
> The generated helpers do not have the if (helper->funcs->fb_dirty)
> check.
> Is this implemented somewhere else that I missed?

It's not needed any longer.  We used to test if the fbdev code needs 
damage handling by looking for a fb_dirty callback. If so, we ran the 
damage handling code.

With the patchset applied, the fbdev code that does not need damage 
handling calls fb_{io,sys}_write() directly.  The fbdev code that needs 
damage handling (generic, i915, msm) uses the generator macro that 
creates necessary the calls unconditionally.  We know each case at build 
time.

(I think I have to move the msm patch after patch 10/13 to make it 
bisectable.)

AFAICT the missing test for fb_dirty is also one of the reasons why 
there's a difference in performance.

Hopefully, this answers your question?

Best regards
Thomas

> 
> 	Sam
> 
> 
>> -
>> -	return ret;
>> -}
>> -EXPORT_SYMBOL(drm_fb_helper_cfb_write);
>> -
>> -/**
>> - * drm_fb_helper_cfb_fillrect - wrapper around cfb_fillrect
>> - * @info: fbdev registered by the helper
>> - * @rect: info about rectangle to fill
>> - *
>> - * A wrapper around cfb_fillrect implemented by fbdev core
>> - */
>> -void drm_fb_helper_cfb_fillrect(struct fb_info *info,
>> -				const struct fb_fillrect *rect)
>> -{
>> -	struct drm_fb_helper *helper = info->par;
>> -
>> -	cfb_fillrect(info, rect);
>> -
>> -	if (helper->funcs->fb_dirty)
>> -		drm_fb_helper_damage(helper, rect->dx, rect->dy, rect->width, rect->height);
>> -}
>> -EXPORT_SYMBOL(drm_fb_helper_cfb_fillrect);
>> -
>> -/**
>> - * drm_fb_helper_cfb_copyarea - wrapper around cfb_copyarea
>> - * @info: fbdev registered by the helper
>> - * @area: info about area to copy
>> - *
>> - * A wrapper around cfb_copyarea implemented by fbdev core
>> - */
>> -void drm_fb_helper_cfb_copyarea(struct fb_info *info,
>> -				const struct fb_copyarea *area)
>> -{
>> -	struct drm_fb_helper *helper = info->par;
>> -
>> -	cfb_copyarea(info, area);
>> -
>> -	if (helper->funcs->fb_dirty)
>> -		drm_fb_helper_damage(helper, area->dx, area->dy, area->width, area->height);
>> -}
>> -EXPORT_SYMBOL(drm_fb_helper_cfb_copyarea);
>> -
>> -/**
>> - * drm_fb_helper_cfb_imageblit - wrapper around cfb_imageblit
>> - * @info: fbdev registered by the helper
>> - * @image: info about image to blit
>> - *
>> - * A wrapper around cfb_imageblit implemented by fbdev core
>> - */
>> -void drm_fb_helper_cfb_imageblit(struct fb_info *info,
>> -				 const struct fb_image *image)
>> -{
>> -	struct drm_fb_helper *helper = info->par;
>> -
>> -	cfb_imageblit(info, image);
>> -
>> -	if (helper->funcs->fb_dirty)
>> -		drm_fb_helper_damage(helper, image->dx, image->dy, image->width, image->height);
>> -}
>> -EXPORT_SYMBOL(drm_fb_helper_cfb_imageblit);
>> -
>>   /**
>>    * drm_fb_helper_set_suspend - wrapper around fb_set_suspend
>>    * @fb_helper: driver-allocated fbdev helper, can be NULL
>> diff --git a/drivers/gpu/drm/i915/Kconfig b/drivers/gpu/drm/i915/Kconfig
>> index e4f4d2e3fdfe..01b5a8272a27 100644
>> --- a/drivers/gpu/drm/i915/Kconfig
>> +++ b/drivers/gpu/drm/i915/Kconfig
>> @@ -17,6 +17,7 @@ config DRM_I915
>>   	select DRM_KMS_HELPER
>>   	select DRM_PANEL
>>   	select DRM_MIPI_DSI
>> +	select FB_IO_HELPERS if DRM_FBDEV_EMULATION
>>   	select RELAY
>>   	select I2C
>>   	select I2C_ALGOBIT
>> diff --git a/drivers/gpu/drm/i915/display/intel_fbdev.c b/drivers/gpu/drm/i915/display/intel_fbdev.c
>> index aab1ae74a8f7..eccaceaf8b9d 100644
>> --- a/drivers/gpu/drm/i915/display/intel_fbdev.c
>> +++ b/drivers/gpu/drm/i915/display/intel_fbdev.c
>> @@ -28,6 +28,7 @@
>>   #include <linux/console.h>
>>   #include <linux/delay.h>
>>   #include <linux/errno.h>
>> +#include <linux/fb.h>
>>   #include <linux/init.h>
>>   #include <linux/kernel.h>
>>   #include <linux/mm.h>
>> @@ -84,6 +85,10 @@ static void intel_fbdev_invalidate(struct intel_fbdev *ifbdev)
>>   	intel_frontbuffer_invalidate(to_frontbuffer(ifbdev), ORIGIN_CPU);
>>   }
>>   
>> +FB_GEN_DEFAULT_DEFERRED_IO_OPS(intel_fbdev,
>> +			       drm_fb_helper_damage_range,
>> +			       drm_fb_helper_damage_area)
>> +
>>   static int intel_fbdev_set_par(struct fb_info *info)
>>   {
>>   	struct intel_fbdev *ifbdev = to_intel_fbdev(info->par);
>> @@ -132,15 +137,12 @@ static int intel_fbdev_mmap(struct fb_info *info, struct vm_area_struct *vma)
>>   
>>   static const struct fb_ops intelfb_ops = {
>>   	.owner = THIS_MODULE,
>> +	__FB_DEFAULT_DEFERRED_OPS_RDWR(intel_fbdev),
>>   	DRM_FB_HELPER_DEFAULT_OPS,
>>   	.fb_set_par = intel_fbdev_set_par,
>> -	.fb_read = drm_fb_helper_cfb_read,
>> -	.fb_write = drm_fb_helper_cfb_write,
>> -	.fb_fillrect = drm_fb_helper_cfb_fillrect,
>> -	.fb_copyarea = drm_fb_helper_cfb_copyarea,
>> -	.fb_imageblit = drm_fb_helper_cfb_imageblit,
>> -	.fb_pan_display = intel_fbdev_pan_display,
>>   	.fb_blank = intel_fbdev_blank,
>> +	.fb_pan_display = intel_fbdev_pan_display,
>> +	__FB_DEFAULT_DEFERRED_OPS_DRAW(intel_fbdev),
>>   	.fb_mmap = intel_fbdev_mmap,
>>   };
>>   
>> diff --git a/include/drm/drm_fb_helper.h b/include/drm/drm_fb_helper.h
>> index b50fd0c0b713..4863b0f8299e 100644
>> --- a/include/drm/drm_fb_helper.h
>> +++ b/include/drm/drm_fb_helper.h
>> @@ -258,18 +258,6 @@ void drm_fb_helper_damage_area(struct fb_info *info, u32 x, u32 y, u32 width, u3
>>   
>>   void drm_fb_helper_deferred_io(struct fb_info *info, struct list_head *pagereflist);
>>   
>> -ssize_t drm_fb_helper_cfb_read(struct fb_info *info, char __user *buf,
>> -			       size_t count, loff_t *ppos);
>> -ssize_t drm_fb_helper_cfb_write(struct fb_info *info, const char __user *buf,
>> -				size_t count, loff_t *ppos);
>> -
>> -void drm_fb_helper_cfb_fillrect(struct fb_info *info,
>> -				const struct fb_fillrect *rect);
>> -void drm_fb_helper_cfb_copyarea(struct fb_info *info,
>> -				const struct fb_copyarea *area);
>> -void drm_fb_helper_cfb_imageblit(struct fb_info *info,
>> -				 const struct fb_image *image);
>> -
>>   void drm_fb_helper_set_suspend(struct drm_fb_helper *fb_helper, bool suspend);
>>   void drm_fb_helper_set_suspend_unlocked(struct drm_fb_helper *fb_helper,
>>   					bool suspend);
>> @@ -385,33 +373,6 @@ static inline int drm_fb_helper_defio_init(struct drm_fb_helper *fb_helper)
>>   	return -ENODEV;
>>   }
>>   
>> -static inline ssize_t drm_fb_helper_cfb_read(struct fb_info *info, char __user *buf,
>> -					     size_t count, loff_t *ppos)
>> -{
>> -	return -ENODEV;
>> -}
>> -
>> -static inline ssize_t drm_fb_helper_cfb_write(struct fb_info *info, const char __user *buf,
>> -					      size_t count, loff_t *ppos)
>> -{
>> -	return -ENODEV;
>> -}
>> -
>> -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,
>>   					     bool suspend)
>>   {
>> -- 
>> 2.40.1
Sam Ravnborg May 30, 2023, 3:37 p.m. UTC | #2
Hi Thomas,

> > > -	if (helper->funcs->fb_dirty) {
> > > -		drm_fb_helper_memory_range_to_clip(info, pos, ret, &damage_area);
> > > -		drm_fb_helper_damage(helper, damage_area.x1, damage_area.y1,
> > > -				     drm_rect_width(&damage_area),
> > > -				     drm_rect_height(&damage_area));
> > > -	}
> > 
> > The generated helpers do not have the if (helper->funcs->fb_dirty)
> > check.
> > Is this implemented somewhere else that I missed?
> 
> It's not needed any longer.  We used to test if the fbdev code needs damage
> handling by looking for a fb_dirty callback. If so, we ran the damage
> handling code.
> 
> With the patchset applied, the fbdev code that does not need damage handling
> calls fb_{io,sys}_write() directly.  The fbdev code that needs damage
> handling (generic, i915, msm) uses the generator macro that creates
> necessary the calls unconditionally.  We know each case at build time.
> 
> (I think I have to move the msm patch after patch 10/13 to make it
> bisectable.)
> 
> AFAICT the missing test for fb_dirty is also one of the reasons why there's
> a difference in performance.
> 
> Hopefully, this answers your question?
Makes perfect sense - thanks.
That also implies that my conditional r-b's are now OK.

	Sam