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Date: Wed, 27 Apr 2016 21:24:52 +0200
From: Noralf Trønnes <noralf@...nnes.org>
To: dri-devel@...ts.freedesktop.org, linux-fbdev@...r.kernel.org,
laurent.pinchart@...asonboard.com, tomi.valkeinen@...com,
linux-kernel@...r.kernel.org
Subject: Re: [PATCH v3 3/7] drm/fb-helper: Add fb_deferred_io support
Den 27.04.2016 21:20, skrev Daniel Vetter:
> On Wed, Apr 27, 2016 at 08:16:32PM +0200, Noralf Trønnes wrote:
>> This adds deferred io support to drm_fb_helper.
>> 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 Trønnes <noralf@...nnes.org>
>> ---
>>
>> Changes since v2:
>> - FB_DEFERRED_IO is now always selected by DRM_KMS_FB_HELPER, ifdef removed
>> - The drm_clip_rect utility functions are dropped, so open code it
>> - docs: use & to denote structs
>>
>> 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/Kconfig | 1 +
>> drivers/gpu/drm/drm_fb_helper.c | 109 +++++++++++++++++++++++++++++++++++++++-
>> include/drm/drm_fb_helper.h | 15 ++++++
>> 3 files changed, 124 insertions(+), 1 deletion(-)
>>
>> diff --git a/drivers/gpu/drm/Kconfig b/drivers/gpu/drm/Kconfig
>> index 9e4f2f1..8e6f34b 100644
>> --- a/drivers/gpu/drm/Kconfig
>> +++ b/drivers/gpu/drm/Kconfig
>> @@ -52,6 +52,7 @@ config DRM_KMS_FB_HELPER
>> select FB_CFB_FILLRECT
>> select FB_CFB_COPYAREA
>> select FB_CFB_IMAGEBLIT
>> + select FB_DEFERRED_IO
>> help
>> FBDEV helpers for KMS drivers.
>>
>> diff --git a/drivers/gpu/drm/drm_fb_helper.c b/drivers/gpu/drm/drm_fb_helper.c
>> index 855108e..5112b5d 100644
>> --- a/drivers/gpu/drm/drm_fb_helper.c
>> +++ b/drivers/gpu/drm/drm_fb_helper.c
>> @@ -48,6 +48,8 @@ MODULE_PARM_DESC(fbdev_emulation,
>>
>> static LIST_HEAD(kernel_fb_helper_list);
>>
>> +static void drm_fb_helper_dirty_init(struct drm_fb_helper *helper);
> Instead of this forward decl just inline the few setup commands into
> drm_fb_helper_prepare.
That would mean that I have to forward declare drm_fb_helper_dirty_work()
instead. Is that better?
Or should I relocate the functions?
>> +
>> /**
>> * DOC: fbdev helpers
>> *
>> @@ -84,6 +86,15 @@ static LIST_HEAD(kernel_fb_helper_list);
>> * and set up an initial configuration using the detected hardware, drivers
>> * should call drm_fb_helper_single_add_all_connectors() followed by
>> * drm_fb_helper_initial_config().
>> + *
>> + * If CONFIG_FB_DEFERRED_IO is enabled and &drm_framebuffer_funcs ->dirty is
>> + * set, the drm_fb_helper_{cfb,sys}_{write,fillrect,copyarea,imageblit}
>> + * functions will accumulate changes and schedule &fb_helper .dirty_work to run
>> + * right away. This worker then calls the dirty() function ensuring that 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.
>> */
>>
>> /**
>> @@ -650,6 +661,7 @@ void drm_fb_helper_prepare(struct drm_device *dev, struct 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 = funcs;
>> helper->dev = dev;
>> }
>> @@ -834,6 +846,82 @@ void drm_fb_helper_unlink_fbi(struct drm_fb_helper *fb_helper)
>> }
>> EXPORT_SYMBOL(drm_fb_helper_unlink_fbi);
>>
>> +static void drm_fb_helper_dirty_work(struct work_struct *work)
>> +{
>> + struct drm_fb_helper *helper = container_of(work, struct drm_fb_helper,
>> + dirty_work);
>> + struct drm_clip_rect *clip = &helper->dirty_clip;
>> + struct drm_clip_rect clip_copy;
>> + unsigned long flags;
>> +
>> + spin_lock_irqsave(&helper->dirty_lock, flags);
>> + clip_copy = *clip;
>> + clip->x1 = clip->y1 = ~0;
>> + clip->x2 = clip->y2 = 0;
>> + spin_unlock_irqrestore(&helper->dirty_lock, flags);
>> +
>> + helper->fb->funcs->dirty(helper->fb, NULL, 0, 0, &clip_copy, 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);
>> + helper->dirty_clip.x1 = helper->dirty_clip.y1 = ~0;
>> +}
>> +
>> +static void drm_fb_helper_dirty(struct fb_info *info, u32 x, u32 y,
>> + u32 width, u32 height)
>> +{
>> + struct drm_fb_helper *helper = info->par;
>> + struct drm_clip_rect *clip = &helper->dirty_clip;
>> + unsigned long flags;
>> +
>> + if (!helper->fb->funcs->dirty)
>> + return;
>> +
>> + spin_lock_irqsave(&helper->dirty_lock, flags);
>> + clip->x1 = min_t(u32, clip->x1, x);
>> + clip->y1 = min_t(u32, clip->y1, y);
>> + clip->x2 = max_t(u32, clip->x2, x + width);
>> + clip->y2 = max_t(u32, clip->y2, y + height);
>> + 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 &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 = ULONG_MAX;
>> + max = 0;
>> + list_for_each_entry(page, pagelist, lru) {
>> + start = page->index << PAGE_SHIFT;
>> + end = start + PAGE_SIZE - 1;
>> + min = min(min, start);
>> + max = max(max, end);
>> + }
>> +
>> + if (min < max) {
>> + y1 = min / info->fix.line_length;
>> + y2 = min_t(u32, max / info->fix.line_length, info->var.yres);
> Needs a DIV_ROUND_UP here I think.
>
> Besides these two nits nothing else I've spotted.
>
> Reviewed-by: Daniel Vetter <daniel.vetter@...ll.ch>
>
>
>> + drm_fb_helper_dirty(info, 0, y1, info->var.xres, y2 - y1);
>> + }
>> +}
>> +EXPORT_SYMBOL(drm_fb_helper_deferred_io);
>> +
>> /**
>> * drm_fb_helper_sys_read - wrapper around fb_sys_read
>> * @info: fb_info struct pointer
>> @@ -862,7 +950,14 @@ EXPORT_SYMBOL(drm_fb_helper_sys_read);
>> ssize_t drm_fb_helper_sys_write(struct fb_info *info, const char __user *buf,
>> size_t count, loff_t *ppos)
>> {
>> - return fb_sys_write(info, buf, count, ppos);
>> + ssize_t ret;
>> +
>> + ret = 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 +972,8 @@ 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 +988,8 @@ void drm_fb_helper_sys_copyarea(struct fb_info *info,
>> 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 +1004,8 @@ void drm_fb_helper_sys_imageblit(struct fb_info *info,
>> 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 +1020,8 @@ void drm_fb_helper_cfb_fillrect(struct fb_info *info,
>> 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 +1036,8 @@ void drm_fb_helper_cfb_copyarea(struct fb_info *info,
>> 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 +1052,8 @@ void drm_fb_helper_cfb_imageblit(struct fb_info *info,
>> 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..5b4aa35 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 damage 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 supporting
>> * fbdev emulation should embedded this into their overall driver structure.
>> @@ -189,6 +193,9 @@ struct drm_fb_helper {
>> const struct drm_fb_helper_funcs *funcs;
>> struct fb_info *fbdev;
>> u32 pseudo_palette[17];
>> + struct drm_clip_rect dirty_clip;
>> + spinlock_t dirty_lock;
>> + struct work_struct dirty_work;
>>
>> /**
>> * @kernel_fb_list:
>> @@ -245,6 +252,9 @@ void drm_fb_helper_fill_fix(struct fb_info *info, uint32_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 __user *buf,
>> @@ -368,6 +378,11 @@ 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
>>
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