[Intel-gfx] [PATCH v4 13/13] drm/i915: Implement dedicated fbdev I/O helpers
Sui Jingfeng
15330273260 at 189.cn
Tue May 30 04:02:01 UTC 2023
Hi,
On 2023/5/30 03:36, Sam Ravnborg wrote:
> 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 at suse.de>
>> Cc: Jani Nikula <jani.nikula at linux.intel.com>
>> Cc: Joonas Lahtinen <joonas.lahtinen at linux.intel.com>
>> Cc: Rodrigo Vivi <rodrigo.vivi at intel.com>
>> Cc: Tvrtko Ursulin <tvrtko.ursulin at linux.intel.com>
>> Cc: "Ville Syrjälä" <ville.syrjala at 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.
Nice catch!
If I understand this correctly, fb_io_write() will write directly to the
ultimate
destination. There no need to check if (helper->funcs->fb_dirty) anymore.
code inside the curly brace of `if (helper->funcs->fb_dirty) { }` can
be delete safely .
This could turn out to be an optimization. This is a benefit of
untangled implement.
previously this is a generic (tangled) implement, which intended to be
used by both
the UMA device driver and non-UMA device(with dedicate VRAM) driver.
drm_fbdev_generic always has a shadow screen buffer allocated in system RAM,
it always has the fb_dirty hooked, so this could be an optimization
for fbdev_generic
by eliminate if (helper->funcs->fb_dirty) check.
while dma helper based driver could switch to drm_fbdev_dma, they writing
to gem buffer directly, no shadow buffer is needed.
With those patch, device driver with dedicated video memory can also
choose FB_CFB_*
to update (iomem)framebuffer directly, despite slower.
> Is this implemented somewhere else that I missed?
>
> Sam
>
drm_fb_helper_fb_dirty() function has a check:
```
if (drm_WARN_ON_ONCE(dev, !helper->funcs->fb_dirty))
return;
```
Not sure if this is a little bit too late......
>> -
>> - 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
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