On Mon, Sep 28, 2020 at 11:13:06AM +0200, Thomas Zimmermann wrote: > Hi > > Am 28.09.20 um 10:53 schrieb Daniel Vetter: > > On Mon, Sep 28, 2020 at 9:22 AM Thomas Zimmermann <tzimmermann@xxxxxxx> wrote: > >> > >> Hi > >> > >> Am 26.09.20 um 18:42 schrieb Daniel Vetter: > >>> On Fri, Sep 25, 2020 at 4:55 PM Thomas Zimmermann <tzimmermann@xxxxxxx> wrote: > >>>> > >>>> Hi > >>>> > >>>> Am 29.06.20 um 10:40 schrieb Daniel Vetter: > >>>>> On Thu, Jun 25, 2020 at 02:00:03PM +0200, Thomas Zimmermann wrote: > >>>>>> The memcpy's destination buffer might have a different pitch than the > >>>>>> source. Support different pitches as function argument. > >>>>>> > >>>>>> Signed-off-by: Thomas Zimmermann <tzimmermann@xxxxxxx> > >>>>> > >>>>> Reviewed-by: Daniel Vetter <daniel.vetter@xxxxxxxx> > >>>>> > >>>>> But I do have questions ... why did we allocate a source drm_framebuffer > >>>>> with mismatching pitch? That sounds backwards, especially for simplekms. > >>>> > >>>> There's userspace that allocates framebuffers in tiles of 64x64 pixels. > >>>> I think I've seen this with Gnome. So if you have a 800x600 display > >>>> mode, the allocated framebuffer has a scanline pitch of 832 pixels and > >>>> the final 32 pixels are ignored. > >>> > >>> At least with dumb buffer allocation ioctls userspace should not do > >>> that. If it wants 800x600, it needs to allocate 800x600, not something > >> > >> That ship has sailed. > > > > Not really, right now that ship is simply leaking and sinking. If we > > decide to patch this up from the kernel side, then indeed it has > > sailed. And I'm not sure that's a good idea. > > We have code in at least cirrus, ast and mgag200 to support this. And > userspace has been behaving like this since at least when I got involved > (2017). Hm where do these drivers copy stuff around and rematch the stride? > >>> else. The driver is supposed to apply any rounding necessary for the > >>> size. Or is this a buffer allocated somewhere else and then shared? > >> > >> I don't quite remember where exactly this was implemented. It was not a > >> shared buffer, though. IIRC the buffer allocation code in one of the > >> libs rounded the size towards multiples of 64. I remember thinking that > >> it was probably done for tiled rendering. > > > > Yeah, but you don't do rendering on dumb buffers. Like ever. So this > > smells like a userspace bug. > > It's also part of the software rendering. It is not a bug, but > implemented deliberately in one of the userspace components that > allocates framebuffers (but I cannot remember which one.) I think it would be good to document this. We already fake xrgb8888 everywhere because userspace is not flexible enough, I guess having to fake 64b stride support everywhere isn't that much worse. But it's definitely not great either :-/ -Daniel > > Best regards > Thomas > > > > > If it's for shared buffers then I think that sounds more reasonable. > > -Daniel > > > >> > >> Best regards > >> Thomas > >> > >>> -Daniel > >>> > >>>> In regular drivers, we can handle this with the VGA offset register [1] > >>>> or some equivalent. That's obviously not an option with simplekms, so > >>>> the different pitch is required. > >>>> > >>>> Best regards > >>>> Thomas > >>>> > >>>> [1] > >>>> https://web.stanford.edu/class/cs140/projects/pintos/specs/freevga/vga/crtcreg.htm#13 > >>>> > >>>>> > >>>>> Would be good to add the reasons why we need this to the commit message, > >>>>> I'm sure I'll discover it later on eventually. > >>>>> -Daniel > >>>>> > >>>>>> --- > >>>>>> drivers/gpu/drm/drm_format_helper.c | 9 +++++---- > >>>>>> drivers/gpu/drm/mgag200/mgag200_mode.c | 2 +- > >>>>>> drivers/gpu/drm/tiny/cirrus.c | 2 +- > >>>>>> include/drm/drm_format_helper.h | 2 +- > >>>>>> 4 files changed, 8 insertions(+), 7 deletions(-) > >>>>>> > >>>>>> diff --git a/drivers/gpu/drm/drm_format_helper.c b/drivers/gpu/drm/drm_format_helper.c > >>>>>> index c043ca364c86..8d5a683afea7 100644 > >>>>>> --- a/drivers/gpu/drm/drm_format_helper.c > >>>>>> +++ b/drivers/gpu/drm/drm_format_helper.c > >>>>>> @@ -52,6 +52,7 @@ EXPORT_SYMBOL(drm_fb_memcpy); > >>>>>> /** > >>>>>> * drm_fb_memcpy_dstclip - Copy clip buffer > >>>>>> * @dst: Destination buffer (iomem) > >>>>>> + * @dst_pitch: Number of bytes between two consecutive scanlines within dst > >>>>>> * @vaddr: Source buffer > >>>>>> * @fb: DRM framebuffer > >>>>>> * @clip: Clip rectangle area to copy > >>>>>> @@ -59,12 +60,12 @@ EXPORT_SYMBOL(drm_fb_memcpy); > >>>>>> * This function applies clipping on dst, i.e. the destination is a > >>>>>> * full (iomem) framebuffer but only the clip rect content is copied over. > >>>>>> */ > >>>>>> -void drm_fb_memcpy_dstclip(void __iomem *dst, void *vaddr, > >>>>>> - struct drm_framebuffer *fb, > >>>>>> +void drm_fb_memcpy_dstclip(void __iomem *dst, unsigned int dst_pitch, > >>>>>> + void *vaddr, struct drm_framebuffer *fb, > >>>>>> struct drm_rect *clip) > >>>>>> { > >>>>>> unsigned int cpp = fb->format->cpp[0]; > >>>>>> - unsigned int offset = clip_offset(clip, fb->pitches[0], cpp); > >>>>>> + unsigned int offset = clip_offset(clip, dst_pitch, cpp); > >>>>>> size_t len = (clip->x2 - clip->x1) * cpp; > >>>>>> unsigned int y, lines = clip->y2 - clip->y1; > >>>>>> > >>>>>> @@ -73,7 +74,7 @@ void drm_fb_memcpy_dstclip(void __iomem *dst, void *vaddr, > >>>>>> for (y = 0; y < lines; y++) { > >>>>>> memcpy_toio(dst, vaddr, len); > >>>>>> vaddr += fb->pitches[0]; > >>>>>> - dst += fb->pitches[0]; > >>>>>> + dst += dst_pitch; > >>>>>> } > >>>>>> } > >>>>>> EXPORT_SYMBOL(drm_fb_memcpy_dstclip); > >>>>>> diff --git a/drivers/gpu/drm/mgag200/mgag200_mode.c b/drivers/gpu/drm/mgag200/mgag200_mode.c > >>>>>> index f16bd278ab7e..7d4f3a62d885 100644 > >>>>>> --- a/drivers/gpu/drm/mgag200/mgag200_mode.c > >>>>>> +++ b/drivers/gpu/drm/mgag200/mgag200_mode.c > >>>>>> @@ -1586,7 +1586,7 @@ mgag200_handle_damage(struct mga_device *mdev, struct drm_framebuffer *fb, > >>>>>> if (drm_WARN_ON(dev, !vmap)) > >>>>>> return; /* BUG: SHMEM BO should always be vmapped */ > >>>>>> > >>>>>> - drm_fb_memcpy_dstclip(mdev->vram, vmap, fb, clip); > >>>>>> + drm_fb_memcpy_dstclip(mdev->vram, fb->pitches[0], vmap, fb, clip); > >>>>>> > >>>>>> drm_gem_shmem_vunmap(fb->obj[0], vmap); > >>>>>> > >>>>>> diff --git a/drivers/gpu/drm/tiny/cirrus.c b/drivers/gpu/drm/tiny/cirrus.c > >>>>>> index 744a8e337e41..2dd9e5e31e3d 100644 > >>>>>> --- a/drivers/gpu/drm/tiny/cirrus.c > >>>>>> +++ b/drivers/gpu/drm/tiny/cirrus.c > >>>>>> @@ -327,7 +327,7 @@ static int cirrus_fb_blit_rect(struct drm_framebuffer *fb, > >>>>>> goto out_dev_exit; > >>>>>> > >>>>>> if (cirrus->cpp == fb->format->cpp[0]) > >>>>>> - drm_fb_memcpy_dstclip(cirrus->vram, > >>>>>> + drm_fb_memcpy_dstclip(cirrus->vram, fb->pitches[0], > >>>>>> vmap, fb, rect); > >>>>>> > >>>>>> else if (fb->format->cpp[0] == 4 && cirrus->cpp == 2) > >>>>>> diff --git a/include/drm/drm_format_helper.h b/include/drm/drm_format_helper.h > >>>>>> index 5f9e37032468..2b5036a5fbe7 100644 > >>>>>> --- a/include/drm/drm_format_helper.h > >>>>>> +++ b/include/drm/drm_format_helper.h > >>>>>> @@ -11,7 +11,7 @@ struct drm_rect; > >>>>>> > >>>>>> void drm_fb_memcpy(void *dst, void *vaddr, struct drm_framebuffer *fb, > >>>>>> struct drm_rect *clip); > >>>>>> -void drm_fb_memcpy_dstclip(void __iomem *dst, void *vaddr, > >>>>>> +void drm_fb_memcpy_dstclip(void __iomem *dst, unsigned int dst_pitch, void *vaddr, > >>>>>> struct drm_framebuffer *fb, > >>>>>> struct drm_rect *clip); > >>>>>> void drm_fb_swab(void *dst, void *src, struct drm_framebuffer *fb, > >>>>>> -- > >>>>>> 2.27.0 > >>>>>> > >>>>> > >>>> > >>>> -- > >>>> Thomas Zimmermann > >>>> Graphics Driver Developer > >>>> SUSE Software Solutions Germany GmbH > >>>> Maxfeldstr. 5, 90409 Nürnberg, Germany > >>>> (HRB 36809, AG Nürnberg) > >>>> Geschäftsführer: Felix Imendörffer > >>>> > >>> > >>> > >> > >> -- > >> Thomas Zimmermann > >> Graphics Driver Developer > >> SUSE Software Solutions Germany GmbH > >> Maxfeldstr. 5, 90409 Nürnberg, Germany > >> (HRB 36809, AG Nürnberg) > >> Geschäftsführer: Felix Imendörffer > >> > > > > > > -- > Thomas Zimmermann > Graphics Driver Developer > SUSE Software Solutions Germany GmbH > Maxfeldstr. 5, 90409 Nürnberg, Germany > (HRB 36809, AG Nürnberg) > Geschäftsführer: Felix Imendörffer > -- Daniel Vetter Software Engineer, Intel Corporation http://blog.ffwll.ch _______________________________________________ dri-devel mailing list dri-devel@xxxxxxxxxxxxxxxxxxxxx https://lists.freedesktop.org/mailman/listinfo/dri-devel
