Hi Am 29.09.20 um 11:19 schrieb Daniel Vetter: > 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? They don't. These drivers adopt their HW stride to match whatever userspace framebuffers tell them. [1] And that's because userspace gives them framebuffer sizes like 832*640. And then they do a memcpy with the given width. My sole point here was that userspace already relies on this behavior. Best regards Thomas [1] https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/tree/drivers/gpu/drm/tiny/cirrus.c#n285 > >>>>> 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 >> > > > > -- Thomas Zimmermann Graphics Driver Developer SUSE Software Solutions Germany GmbH Maxfeldstr. 5, 90409 Nürnberg, Germany (HRB 36809, AG Nürnberg) Geschäftsführer: Felix Imendörffer
Attachment:
signature.asc
Description: OpenPGP digital signature
_______________________________________________ dri-devel mailing list dri-devel@xxxxxxxxxxxxxxxxxxxxx https://lists.freedesktop.org/mailman/listinfo/dri-devel
