Re: [v2,11/12] drm/fbdev-generic: Implement dedicated fbdev I/O helpers

[Sui Jingfeng <15330273260@xxxxxx>]

Hi,

On 2023/5/17 15:07, Thomas Zimmermann wrote:
> Hi
>
> Am 17.05.23 um 03:58 schrieb Sui Jingfeng:
> > Hi, Thomas
> >
> >
> > After apply your patch set, the kernel with 
> > arch/loongarch/configs/loongson3_defconfig
> >
> > can not finish compile anymore.  gcc complains:
> >
> >
> >    AR      drivers/gpu/built-in.a
> >    AR      drivers/built-in.a
> >    AR      built-in.a
> >    AR      vmlinux.a
> >    LD      vmlinux.o
> >    OBJCOPY modules.builtin.modinfo
> >    GEN     modules.builtin
> >    GEN     .vmlinux.objs
> >    MODPOST Module.symvers
> > ERROR: modpost: "fb_sys_write" [drivers/gpu/drm/drm_kms_helper.ko] 
> > undefined!
> > ERROR: modpost: "sys_imageblit" [drivers/gpu/drm/drm_kms_helper.ko] 
> > undefined!
> > ERROR: modpost: "sys_fillrect" [drivers/gpu/drm/drm_kms_helper.ko] 
> > undefined!
> > ERROR: modpost: "sys_copyarea" [drivers/gpu/drm/drm_kms_helper.ko] 
> > undefined!
> > ERROR: modpost: "fb_sys_read" [drivers/gpu/drm/drm_kms_helper.ko] 
> > undefined!
> > make[1]: *** [scripts/Makefile.modpost:136: Module.symvers] Error 1
> > make: *** [Makefile:1978: modpost] Error 2
>
> Thanks for reporting this problem. I found that it's caused by a typo 
> in the very first patch 1/7, where these helpers are not selected 
> correctly. Will be fixed in the next round.
Yeah, this is just a typo.

Should replace 'FB_SYS_HELPER' with 'FB_SYS_HELPERS' on the first patch 
of this series.


> Best regards
> Thomas
>
> > On 2023/5/15 17:40, Thomas Zimmermann wrote:
> > > Implement dedicated fbdev helpers for framebuffer I/O instead
> > > of using DRM's helpers. Fbdev-generic was the only caller of the
> > > DRM helpers, so remove them from the helper module.
> > >
> > > v2:
> > >     * use FB_SYS_HELPERS_DEFERRED option
> > >
> > > Signed-off-by: Thomas Zimmermann <tzimmermann@xxxxxxx>
> > > ---
> > >   drivers/gpu/drm/Kconfig             |   6 +-
> > >   drivers/gpu/drm/drm_fb_helper.c     | 107 
> > > ----------------------------
> > >   drivers/gpu/drm/drm_fbdev_generic.c |  47 ++++++++++--
> > >   include/drm/drm_fb_helper.h         |  41 -----------
> > >   4 files changed, 43 insertions(+), 158 deletions(-)
> > >
> > > diff --git a/drivers/gpu/drm/Kconfig b/drivers/gpu/drm/Kconfig
> > > index 77fb10ddd8a2..92a782827b7b 100644
> > > --- a/drivers/gpu/drm/Kconfig
> > > +++ b/drivers/gpu/drm/Kconfig
> > > @@ -95,6 +95,7 @@ config DRM_KUNIT_TEST
> > >   config DRM_KMS_HELPER
> > >       tristate
> > >       depends on DRM
> > > +    select FB_SYS_HELPERS_DEFERRED if DRM_FBDEV_EMULATION
> >
> > Here, select FB_SYS_HELPERS helps resolve the above issue mentioned.
But select FB_SYS_HELPERS here is more better, I think.  Because it show 
the nature that

DRM_KMS_HELPER is depend on FB_SYS_HELPERS, I think you may want isolate

those dependency with DRM_FBDEV_EMULATION guard.

at least, you should guarantee that drm itself could built and run 
standalone.

Fbdev emulation is a client of drm, not reverse.


By the way, does Denial happy about this,

maybe, he want the fbdev emulation 100% made in drm?

> > >       help
> > >         CRTC helpers for KMS drivers.
> > > @@ -135,11 +136,6 @@ config DRM_FBDEV_EMULATION
> > >       select FB_CFB_FILLRECT
> > >       select FB_CFB_COPYAREA
> > >       select FB_CFB_IMAGEBLIT
> > > -    select FB_DEFERRED_IO
> > > -    select FB_SYS_FOPS
> > > -    select FB_SYS_FILLRECT
> > > -    select FB_SYS_COPYAREA
> > > -    select FB_SYS_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 8724e08c518b..ba0a808f14ee 100644
> > > --- a/drivers/gpu/drm/drm_fb_helper.c
> > > +++ b/drivers/gpu/drm/drm_fb_helper.c
> > > @@ -729,113 +729,6 @@ void drm_fb_helper_deferred_io(struct fb_info 
> > > *info, struct list_head *pagerefli
> > >   }
> > >   EXPORT_SYMBOL(drm_fb_helper_deferred_io);
> > > -/**
> > > - * drm_fb_helper_sys_read - Implements struct &fb_ops.fb_read for 
> > > system 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_sys_read(struct fb_info *info, char __user *buf,
> > > -                   size_t count, loff_t *ppos)
> > > -{
> > > -    return fb_sys_read(info, buf, count, ppos);
> > > -}
> > > -EXPORT_SYMBOL(drm_fb_helper_sys_read);
> > > -
> > > -/**
> > > - * drm_fb_helper_sys_write - Implements struct &fb_ops.fb_write for 
> > > system 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_sys_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_sys_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));
> > > -    }
> > > -
> > > -    return ret;
> > > -}
> > > -EXPORT_SYMBOL(drm_fb_helper_sys_write);
> > > -
> > > -/**
> > > - * drm_fb_helper_sys_fillrect - wrapper around sys_fillrect
> > > - * @info: fbdev registered by the helper
> > > - * @rect: info about rectangle to fill
> > > - *
> > > - * A wrapper around sys_fillrect implemented by fbdev core
> > > - */
> > > -void drm_fb_helper_sys_fillrect(struct fb_info *info,
> > > -                const struct fb_fillrect *rect)
> > > -{
> > > -    struct drm_fb_helper *helper = info->par;
> > > -
> > > -    sys_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_sys_fillrect);
> > > -
> > > -/**
> > > - * drm_fb_helper_sys_copyarea - wrapper around sys_copyarea
> > > - * @info: fbdev registered by the helper
> > > - * @area: info about area to copy
> > > - *
> > > - * A wrapper around sys_copyarea implemented by fbdev core
> > > - */
> > > -void drm_fb_helper_sys_copyarea(struct fb_info *info,
> > > -                const struct fb_copyarea *area)
> > > -{
> > > -    struct drm_fb_helper *helper = info->par;
> > > -
> > > -    sys_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_sys_copyarea);
> > > -
> > > -/**
> > > - * drm_fb_helper_sys_imageblit - wrapper around sys_imageblit
> > > - * @info: fbdev registered by the helper
> > > - * @image: info about image to blit
> > > - *
> > > - * A wrapper around sys_imageblit implemented by fbdev core
> > > - */
> > > -void drm_fb_helper_sys_imageblit(struct fb_info *info,
> > > -                 const struct fb_image *image)
> > > -{
> > > -    struct drm_fb_helper *helper = info->par;
> > > -
> > > -    sys_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_sys_imageblit);
> > > -
> > >   /**
> > >    * drm_fb_helper_cfb_read - Implements struct &fb_ops.fb_read for 
> > > I/O memory
> > >    * @info: fb_info struct pointer
> > > diff --git a/drivers/gpu/drm/drm_fbdev_generic.c 
> > > b/drivers/gpu/drm/drm_fbdev_generic.c
> > > index 8e5148bf40bb..f53fc49e34a4 100644
> > > --- a/drivers/gpu/drm/drm_fbdev_generic.c
> > > +++ b/drivers/gpu/drm/drm_fbdev_generic.c
> > > @@ -34,6 +34,43 @@ static int drm_fbdev_generic_fb_release(struct 
> > > fb_info *info, int user)
> > >       return 0;
> > >   }
> > > +static ssize_t drm_fbdev_generic_fb_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;
> > > +
> > > +    ret = fb_sys_write(info, buf, count, ppos);
> > > +    if (ret > 0)
> > > +        drm_fb_helper_damage_range(helper, pos, ret);
> > > +    return ret;
> > > +}
> > > +
> > > +static void drm_fbdev_generic_fb_fillrect(struct fb_info *info, 
> > > const struct fb_fillrect *rect)
> > > +{
> > > +    struct drm_fb_helper *helper = info->par;
> > > +
> > > +    sys_fillrect(info, rect);
> > > +    drm_fb_helper_damage(helper, rect->dx, rect->dy, rect->width, 
> > > rect->height);
> > > +}
> > > +
> > > +static void drm_fbdev_generic_fb_copyarea(struct fb_info *info, 
> > > const struct fb_copyarea *area)
> > > +{
> > > +    struct drm_fb_helper *helper = info->par;
> > > +
> > > +    sys_copyarea(info, area);
> > > +    drm_fb_helper_damage(helper, area->dx, area->dy, area->width, 
> > > area->height);
> > > +}
> > > +
> > > +static void drm_fbdev_generic_fb_imageblit(struct fb_info *info, 
> > > const struct fb_image *image)
> > > +{
> > > +    struct drm_fb_helper *helper = info->par;
> > > +
> > > +    sys_imageblit(info, image);
> > > +    drm_fb_helper_damage(helper, image->dx, image->dy, 
> > > image->width, image->height);
> > > +}
> > > +
> > >   static void drm_fbdev_generic_fb_destroy(struct fb_info *info)
> > >   {
> > >       struct drm_fb_helper *fb_helper = info->par;
> > > @@ -56,12 +93,12 @@ static const struct fb_ops 
> > > drm_fbdev_generic_fb_ops = {
> > >       .owner        = THIS_MODULE,
> > >       .fb_open    = drm_fbdev_generic_fb_open,
> > >       .fb_release    = drm_fbdev_generic_fb_release,
> > > -    .fb_read    = drm_fb_helper_sys_read,
> > > -    .fb_write    = drm_fb_helper_sys_write,
> > > +    .fb_read    = fb_sys_read,
> > > +    .fb_write    = drm_fbdev_generic_fb_write,
> > >       DRM_FB_HELPER_DEFAULT_OPS,
> > > -    .fb_fillrect    = drm_fb_helper_sys_fillrect,
> > > -    .fb_copyarea    = drm_fb_helper_sys_copyarea,
> > > -    .fb_imageblit    = drm_fb_helper_sys_imageblit,
> > > +    .fb_fillrect    = drm_fbdev_generic_fb_fillrect,
> > > +    .fb_copyarea    = drm_fbdev_generic_fb_copyarea,
> > > +    .fb_imageblit    = drm_fbdev_generic_fb_imageblit,
> > >       .fb_mmap    = fb_deferred_io_mmap,
> > >       .fb_destroy    = drm_fbdev_generic_fb_destroy,
> > >   };
> > > diff --git a/include/drm/drm_fb_helper.h b/include/drm/drm_fb_helper.h
> > > index 80c402f4e379..e3240d749a43 100644
> > > --- a/include/drm/drm_fb_helper.h
> > > +++ b/include/drm/drm_fb_helper.h
> > > @@ -259,18 +259,6 @@ void drm_fb_helper_damage_range(struct 
> > > drm_fb_helper *helper, off_t off, size_t
> > >   void drm_fb_helper_deferred_io(struct fb_info *info, struct 
> > > list_head *pagereflist);
> > > -ssize_t drm_fb_helper_sys_read(struct fb_info *info, char __user *buf,
> > > -                   size_t count, loff_t *ppos);
> > > -ssize_t drm_fb_helper_sys_write(struct fb_info *info, const char 
> > > __user *buf,
> > > -                size_t count, loff_t *ppos);
> > > -
> > > -void drm_fb_helper_sys_fillrect(struct fb_info *info,
> > > -                const struct fb_fillrect *rect);
> > > -void drm_fb_helper_sys_copyarea(struct fb_info *info,
> > > -                const struct fb_copyarea *area);
> > > -void drm_fb_helper_sys_imageblit(struct fb_info *info,
> > > -                 const struct fb_image *image);
> > > -
> > >   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,
> > > @@ -398,35 +386,6 @@ static inline int 
> > > drm_fb_helper_defio_init(struct drm_fb_helper *fb_helper)
> > >       return -ENODEV;
> > >   }
> > > -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 ssize_t drm_fb_helper_cfb_read(struct fb_info *info, 
> > > char __user *buf,
> > >                            size_t count, loff_t *ppos)
> > >   {