From mboxrd@z Thu Jan 1 00:00:00 1970 From: =?UTF-8?Q?Noralf_Tr=c3=b8nnes?= Date: Tue, 26 Apr 2016 16:24:54 +0000 Subject: Re: [PATCH v2 4/8] drm/fb-helper: Add fb_deferred_io support Message-Id: <571F9656.1090506@tronnes.org> List-Id: References: <1461530942-22485-1-git-send-email-noralf@tronnes.org> <1461530942-22485-5-git-send-email-noralf@tronnes.org> <20160425090957.GQ2510@phenom.ffwll.local> In-Reply-To: <20160425090957.GQ2510@phenom.ffwll.local> MIME-Version: 1.0 Content-Type: text/plain; charset="iso-8859-1" Content-Transfer-Encoding: quoted-printable To: dri-devel@lists.freedesktop.org, linux-fbdev@vger.kernel.org, laurent.pinchart@ideasonboard.com, tomi.valkeinen@ti.com, linux-kernel@vger.kernel.org Den 25.04.2016 11:09, skrev Daniel Vetter: > On Sun, Apr 24, 2016 at 10:48:58PM +0200, Noralf Tr=F8nnes wrote: >> This adds deferred io support if CONFIG_FB_DEFERRED_IO is enabled. >> The fbdev framebuffer changes are flushed using the callback >> (struct drm_framebuffer *)->funcs->dirty() by a dedicated worker >> ensuring that it always runs in process context. >> >> Signed-off-by: Noralf Tr=F8nnes >> --- >> >> Changes since v1: >> - Use a dedicated worker to run the framebuffer flushing like qxl does >> - Add parameter descriptions to drm_fb_helper_deferred_io >> >> drivers/gpu/drm/drm_fb_helper.c | 127 ++++++++++++++++++++++++++++++++= +++++++- >> include/drm/drm_fb_helper.h | 17 ++++++ >> 2 files changed, 143 insertions(+), 1 deletion(-) >> >> diff --git a/drivers/gpu/drm/drm_fb_helper.c b/drivers/gpu/drm/drm_fb_he= lper.c >> index 855108e..46ee6f8 100644 >> --- a/drivers/gpu/drm/drm_fb_helper.c >> +++ b/drivers/gpu/drm/drm_fb_helper.c >> @@ -40,6 +40,7 @@ >> #include >> #include >> #include >> +#include >> >> static bool drm_fbdev_emulation =3D true; >> module_param_named(fbdev_emulation, drm_fbdev_emulation, bool, 0600); >> @@ -48,6 +49,10 @@ MODULE_PARM_DESC(fbdev_emulation, >> >> static LIST_HEAD(kernel_fb_helper_list); >> >> +static void drm_fb_helper_dirty_init(struct drm_fb_helper *helper); >> +static void drm_fb_helper_dirty(struct fb_info *info, u32 x, u32 y, >> + u32 width, u32 height); >> + >> /** >> * DOC: fbdev helpers >> * >> @@ -84,6 +89,16 @@ static LIST_HEAD(kernel_fb_helper_list); >> * and set up an initial configuration using the detected hardware, dr= ivers >> * should call drm_fb_helper_single_add_all_connectors() followed by >> * drm_fb_helper_initial_config(). >> + * >> + * If CONFIG_FB_DEFERRED_IO is enabled and >> + * (struct drm_framebuffer *)->funcs->dirty is set, the >> + * drm_fb_helper_{cfb,sys}_{write,fillrect,copyarea,imageblit} functions >> + * will accumulate changes and schedule (struct fb_helper).dirty_work t= o run >> + * right away. This worker then calls the dirty() function ensuring tha= t it >> + * will always run in process context since the fb_*() function could be >> + * running in atomic context. If drm_fb_helper_deferred_io() is used as= the >> + * deferred_io callback it will also schedule dirty_work with the damage >> + * collected from the mmap page writes. > One thing to consider (and personally I don't care either way) is whether > we shouldn't just select CONFIG_FB_DEFERRED_IO if the fbdev helpers are > enabled. Pushing that out to drivers is imo a bit fragile. > > But like I said I'm ok with either way. My concern was adding code and data that only a few drivers would actually use. But of course there's the tradeoff with complexity. I use this to enable it: select FB_DEFERRED_IO if DRM_KMS_FB_HELPER I guess the maintainer has to make this choice between size and=20 complexity :-) I can enable it by default if you want, drm is both huge and complex so I don't know what's best. As a sidenote, I have also put all the fbdev code in a file of it's own to make it simple with regards to the DRM_FBDEV_EMULATION user option: tinydrm-$(CONFIG_DRM_KMS_FB_HELPER) +=3D tinydrm-fbdev.o >> */ >> >> /** >> @@ -401,11 +416,14 @@ backoff: >> static int restore_fbdev_mode(struct drm_fb_helper *fb_helper) >> { >> struct drm_device *dev =3D fb_helper->dev; >> + struct fb_info *info =3D fb_helper->fbdev; >> struct drm_plane *plane; >> int i; >> >> drm_warn_on_modeset_not_all_locked(dev); >> >> + drm_fb_helper_dirty(info, 0, 0, info->var.xres, info->var.yres); > Why is this needed? If you do a modeset (or pageflip or whatever) drivers > are supposed to re-upload the entire screen. We've talked about adding a > dirty rectangle to atomic to allow userspace to optimize this, but there > should _never_ be a need to do a dirtyfb call around a modeset. Probably > just a driver bug in your panel drm drivers? Ok, in tinydrm I now set a flag in &drm_simple_display_pipe_funcs ->plane_update to indicate that the next dirty() should do the whole framebuffer which seems to work fine. Should I actually perform the update as well? If so I would need to add a worker in tinydrm to do that. Noralf. > With the above line removed: > > Reviewed-by: Daniel Vetter > >> + >> if (fb_helper->atomic) >> return restore_fbdev_mode_atomic(fb_helper); >> >> @@ -650,6 +668,7 @@ void drm_fb_helper_prepare(struct drm_device *dev, s= truct drm_fb_helper *helper, >> const struct drm_fb_helper_funcs *funcs) >> { >> INIT_LIST_HEAD(&helper->kernel_fb_list); >> + drm_fb_helper_dirty_init(helper); >> helper->funcs =3D funcs; >> helper->dev =3D dev; >> } >> @@ -834,6 +853,93 @@ void drm_fb_helper_unlink_fbi(struct drm_fb_helper = *fb_helper) >> } >> EXPORT_SYMBOL(drm_fb_helper_unlink_fbi); >> >> +#ifdef CONFIG_FB_DEFERRED_IO >> +static void drm_fb_helper_dirty_work(struct work_struct *work) >> +{ >> + struct drm_fb_helper *helper =3D container_of(work, struct drm_fb_help= er, >> + dirty_work); >> + struct drm_clip_rect clip; >> + unsigned long flags; >> + >> + spin_lock_irqsave(&helper->dirty_lock, flags); >> + clip =3D helper->dirty_clip; >> + drm_clip_rect_reset(&helper->dirty_clip); >> + spin_unlock_irqrestore(&helper->dirty_lock, flags); >> + >> + helper->fb->funcs->dirty(helper->fb, NULL, 0, 0, &clip, 1); >> +} >> + >> +static void drm_fb_helper_dirty_init(struct drm_fb_helper *helper) >> +{ >> + spin_lock_init(&helper->dirty_lock); >> + INIT_WORK(&helper->dirty_work, drm_fb_helper_dirty_work); >> +} >> + >> +static void drm_fb_helper_dirty(struct fb_info *info, u32 x, u32 y, >> + u32 width, u32 height) >> +{ >> + struct drm_fb_helper *helper =3D info->par; >> + struct drm_clip_rect clip; >> + unsigned long flags; >> + >> + if (!helper->fb->funcs->dirty) >> + return; >> + >> + clip.x1 =3D x; >> + clip.x2 =3D x + width; >> + clip.y1 =3D y; >> + clip.y2 =3D y + height; >> + >> + spin_lock_irqsave(&helper->dirty_lock, flags); >> + drm_clip_rect_merge(&helper->dirty_clip, &clip, 1, 0, 0, 0); >> + spin_unlock_irqrestore(&helper->dirty_lock, flags); >> + >> + schedule_work(&helper->dirty_work); >> +} >> + >> +/** >> + * drm_fb_helper_deferred_io() - fbdev deferred_io callback function >> + * @info: fb_info struct pointer >> + * @pagelist: list of dirty mmap framebuffer pages >> + * >> + * This function is used as the (struct fb_deferred_io *)->deferred_io >> + * callback function for flushing the fbdev mmap writes. >> + */ >> +void drm_fb_helper_deferred_io(struct fb_info *info, >> + struct list_head *pagelist) >> +{ >> + unsigned long start, end, min, max; >> + struct page *page; >> + u32 y1, y2; >> + >> + min =3D ULONG_MAX; >> + max =3D 0; >> + list_for_each_entry(page, pagelist, lru) { >> + start =3D page->index << PAGE_SHIFT; >> + end =3D start + PAGE_SIZE - 1; >> + min =3D min(min, start); >> + max =3D max(max, end); >> + } >> + >> + if (min < max) { >> + y1 =3D min / info->fix.line_length; >> + y2 =3D min_t(u32, max / info->fix.line_length, info->var.yres); >> + drm_fb_helper_dirty(info, 0, y1, info->var.xres, y2 - y1); >> + } >> +} >> +EXPORT_SYMBOL(drm_fb_helper_deferred_io); >> + >> +#else >> +static void drm_fb_helper_dirty_init(struct drm_fb_helper *helper) >> +{ >> +} >> + >> +static void drm_fb_helper_dirty(struct fb_info *info, u32 x, u32 y, >> + u32 width, u32 height) >> +{ >> +} >> +#endif /* CONFIG_FB_DEFERRED_IO */ >> + >> /** >> * drm_fb_helper_sys_read - wrapper around fb_sys_read >> * @info: fb_info struct pointer >> @@ -862,7 +968,14 @@ EXPORT_SYMBOL(drm_fb_helper_sys_read); >> ssize_t drm_fb_helper_sys_write(struct fb_info *info, const char __use= r *buf, >> size_t count, loff_t *ppos) >> { >> - return fb_sys_write(info, buf, count, ppos); >> + ssize_t ret; >> + >> + ret =3D fb_sys_write(info, buf, count, ppos); >> + if (ret > 0) >> + drm_fb_helper_dirty(info, 0, 0, info->var.xres, >> + info->var.yres); >> + >> + return ret; >> } >> EXPORT_SYMBOL(drm_fb_helper_sys_write); >> >> @@ -877,6 +990,8 @@ void drm_fb_helper_sys_fillrect(struct fb_info *info, >> const struct fb_fillrect *rect) >> { >> sys_fillrect(info, rect); >> + drm_fb_helper_dirty(info, rect->dx, rect->dy, >> + rect->width, rect->height); >> } >> EXPORT_SYMBOL(drm_fb_helper_sys_fillrect); >> >> @@ -891,6 +1006,8 @@ void drm_fb_helper_sys_copyarea(struct fb_info *inf= o, >> const struct fb_copyarea *area) >> { >> sys_copyarea(info, area); >> + drm_fb_helper_dirty(info, area->dx, area->dy, >> + area->width, area->height); >> } >> EXPORT_SYMBOL(drm_fb_helper_sys_copyarea); >> >> @@ -905,6 +1022,8 @@ void drm_fb_helper_sys_imageblit(struct fb_info *in= fo, >> const struct fb_image *image) >> { >> sys_imageblit(info, image); >> + drm_fb_helper_dirty(info, image->dx, image->dy, >> + image->width, image->height); >> } >> EXPORT_SYMBOL(drm_fb_helper_sys_imageblit); >> >> @@ -919,6 +1038,8 @@ void drm_fb_helper_cfb_fillrect(struct fb_info *inf= o, >> const struct fb_fillrect *rect) >> { >> cfb_fillrect(info, rect); >> + drm_fb_helper_dirty(info, rect->dx, rect->dy, >> + rect->width, rect->height); >> } >> EXPORT_SYMBOL(drm_fb_helper_cfb_fillrect); >> >> @@ -933,6 +1054,8 @@ void drm_fb_helper_cfb_copyarea(struct fb_info *inf= o, >> const struct fb_copyarea *area) >> { >> cfb_copyarea(info, area); >> + drm_fb_helper_dirty(info, area->dx, area->dy, >> + area->width, area->height); >> } >> EXPORT_SYMBOL(drm_fb_helper_cfb_copyarea); >> >> @@ -947,6 +1070,8 @@ void drm_fb_helper_cfb_imageblit(struct fb_info *in= fo, >> const struct fb_image *image) >> { >> cfb_imageblit(info, image); >> + drm_fb_helper_dirty(info, image->dx, image->dy, >> + image->width, image->height); >> } >> EXPORT_SYMBOL(drm_fb_helper_cfb_imageblit); >> >> diff --git a/include/drm/drm_fb_helper.h b/include/drm/drm_fb_helper.h >> index 062723b..dde825c 100644 >> --- a/include/drm/drm_fb_helper.h >> +++ b/include/drm/drm_fb_helper.h >> @@ -172,6 +172,10 @@ struct drm_fb_helper_connector { >> * @funcs: driver callbacks for fb helper >> * @fbdev: emulated fbdev device info struct >> * @pseudo_palette: fake palette of 16 colors >> + * @dirty_clip: clip rectangle used with deferred_io to accumulate dama= ge to >> + * the screen buffer >> + * @dirty_lock: spinlock protecting @dirty_clip >> + * @dirty_work: worker used to flush the framebuffer >> * >> * This is the main structure used by the fbdev helpers. Drivers suppo= rting >> * fbdev emulation should embedded this into their overall driver stru= cture. >> @@ -189,6 +193,11 @@ struct drm_fb_helper { >> const struct drm_fb_helper_funcs *funcs; >> struct fb_info *fbdev; >> u32 pseudo_palette[17]; >> +#ifdef CONFIG_FB_DEFERRED_IO >> + struct drm_clip_rect dirty_clip; >> + spinlock_t dirty_lock; >> + struct work_struct dirty_work; >> +#endif >> >> /** >> * @kernel_fb_list: >> @@ -245,6 +254,9 @@ void drm_fb_helper_fill_fix(struct fb_info *info, ui= nt32_t pitch, >> >> void drm_fb_helper_unlink_fbi(struct drm_fb_helper *fb_helper); >> >> +void drm_fb_helper_deferred_io(struct fb_info *info, >> + struct list_head *pagelist); >> + >> 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 __use= r *buf, >> @@ -368,6 +380,11 @@ static inline void drm_fb_helper_unlink_fbi(struct = drm_fb_helper *fb_helper) >> { >> } >> >> +static inline void drm_fb_helper_deferred_io(struct fb_info *info, >> + struct list_head *pagelist) >> +{ >> +} >> + >> static inline ssize_t drm_fb_helper_sys_read(struct fb_info *info, >> char __user *buf, size_t count, >> loff_t *ppos) >> -- >> 2.2.2 >>