Re: [PATCH v4 13/13] drm/i915: Implement dedicated fbdev I/O helpers

[Sam Ravnborg <sam@ravnborg.org>]

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?

	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