Mark screen buffers in system memory with FB_VIRTFB. Otherwise, the buffers are mmap'ed as I/O memory (i.e., VM_IO). For shadow buffers, also set the FB_READS_FAST hint.
Signed-off-by: Thomas Zimmermann tzimmermann@suse.de --- drivers/gpu/drm/drm_fb_helper.c | 9 ++++++--- 1 file changed, 6 insertions(+), 3 deletions(-)
diff --git a/drivers/gpu/drm/drm_fb_helper.c b/drivers/gpu/drm/drm_fb_helper.c index ed43b987d306..f15127a32f7a 100644 --- a/drivers/gpu/drm/drm_fb_helper.c +++ b/drivers/gpu/drm/drm_fb_helper.c @@ -2346,6 +2346,7 @@ static int drm_fb_helper_generic_probe(struct drm_fb_helper *fb_helper, fbi->fbops = &drm_fbdev_fb_ops; fbi->screen_size = sizes->surface_height * fb->pitches[0]; fbi->fix.smem_len = fbi->screen_size; + fbi->flags = FBINFO_DEFAULT;
drm_fb_helper_fill_info(fbi, fb_helper, sizes);
@@ -2353,19 +2354,21 @@ static int drm_fb_helper_generic_probe(struct drm_fb_helper *fb_helper, fbi->screen_buffer = vzalloc(fbi->screen_size); if (!fbi->screen_buffer) return -ENOMEM; + fbi->flags |= FBINFO_VIRTFB | FBINFO_READS_FAST;
fbi->fbdefio = &drm_fbdev_defio; - fb_deferred_io_init(fbi); } else { /* buffer is mapped for HW framebuffer */ ret = drm_client_buffer_vmap(fb_helper->buffer, &map); if (ret) return ret; - if (map.is_iomem) + if (map.is_iomem) { fbi->screen_base = map.vaddr_iomem; - else + } else { fbi->screen_buffer = map.vaddr; + fbi->flags |= FBINFO_VIRTFB; + }
/* * Shamelessly leak the physical address to user-space. As
Am 27.01.22 um 11:26 schrieb Thomas Zimmermann:
Mark screen buffers in system memory with FB_VIRTFB. Otherwise, the
FBINFO_ is the name. Will be fixed before merging
buffers are mmap'ed as I/O memory (i.e., VM_IO). For shadow buffers, also set the FB_READS_FAST hint.
Signed-off-by: Thomas Zimmermann tzimmermann@suse.de
drivers/gpu/drm/drm_fb_helper.c | 9 ++++++--- 1 file changed, 6 insertions(+), 3 deletions(-)
diff --git a/drivers/gpu/drm/drm_fb_helper.c b/drivers/gpu/drm/drm_fb_helper.c index ed43b987d306..f15127a32f7a 100644 --- a/drivers/gpu/drm/drm_fb_helper.c +++ b/drivers/gpu/drm/drm_fb_helper.c @@ -2346,6 +2346,7 @@ static int drm_fb_helper_generic_probe(struct drm_fb_helper *fb_helper, fbi->fbops = &drm_fbdev_fb_ops; fbi->screen_size = sizes->surface_height * fb->pitches[0]; fbi->fix.smem_len = fbi->screen_size;
fbi->flags = FBINFO_DEFAULT;
drm_fb_helper_fill_info(fbi, fb_helper, sizes);
@@ -2353,19 +2354,21 @@ static int drm_fb_helper_generic_probe(struct drm_fb_helper *fb_helper, fbi->screen_buffer = vzalloc(fbi->screen_size); if (!fbi->screen_buffer) return -ENOMEM;
fbi->flags |= FBINFO_VIRTFB | FBINFO_READS_FAST;fbi->fbdefio = &drm_fbdev_defio;
- fb_deferred_io_init(fbi); } else { /* buffer is mapped for HW framebuffer */ ret = drm_client_buffer_vmap(fb_helper->buffer, &map); if (ret) return ret;
if (map.is_iomem)
if (map.is_iomem) { fbi->screen_base = map.vaddr_iomem;
else
} else { fbi->screen_buffer = map.vaddr;fbi->flags |= FBINFO_VIRTFB;}/*
- Shamelessly leak the physical address to user-space. As
On Thu, Jan 27, 2022 at 11:26:21AM +0100, Thomas Zimmermann wrote:
Mark screen buffers in system memory with FB_VIRTFB. Otherwise, the buffers are mmap'ed as I/O memory (i.e., VM_IO). For shadow buffers, also set the FB_READS_FAST hint.
Maybe clarify that this only holds for the defio case, and since we have our own shadow copy for that anyway it shouldn't matter. I'm also not sure how much the memcpy gains us compared to just redrawing ...
What's the motivation here, or just something you spotted? -Daniel
Signed-off-by: Thomas Zimmermann tzimmermann@suse.de
drivers/gpu/drm/drm_fb_helper.c | 9 ++++++--- 1 file changed, 6 insertions(+), 3 deletions(-)
diff --git a/drivers/gpu/drm/drm_fb_helper.c b/drivers/gpu/drm/drm_fb_helper.c index ed43b987d306..f15127a32f7a 100644 --- a/drivers/gpu/drm/drm_fb_helper.c +++ b/drivers/gpu/drm/drm_fb_helper.c @@ -2346,6 +2346,7 @@ static int drm_fb_helper_generic_probe(struct drm_fb_helper *fb_helper, fbi->fbops = &drm_fbdev_fb_ops; fbi->screen_size = sizes->surface_height * fb->pitches[0]; fbi->fix.smem_len = fbi->screen_size;
fbi->flags = FBINFO_DEFAULT;
drm_fb_helper_fill_info(fbi, fb_helper, sizes);
@@ -2353,19 +2354,21 @@ static int drm_fb_helper_generic_probe(struct drm_fb_helper *fb_helper, fbi->screen_buffer = vzalloc(fbi->screen_size); if (!fbi->screen_buffer) return -ENOMEM;
fbi->flags |= FBINFO_VIRTFB | FBINFO_READS_FAST;fbi->fbdefio = &drm_fbdev_defio;
- fb_deferred_io_init(fbi); } else { /* buffer is mapped for HW framebuffer */ ret = drm_client_buffer_vmap(fb_helper->buffer, &map); if (ret) return ret;
if (map.is_iomem)
if (map.is_iomem) { fbi->screen_base = map.vaddr_iomem;
else
} else { fbi->screen_buffer = map.vaddr;fbi->flags |= FBINFO_VIRTFB;}/*
- Shamelessly leak the physical address to user-space. As
-- 2.34.1
Hi
Am 27.01.22 um 12:42 schrieb Daniel Vetter:
On Thu, Jan 27, 2022 at 11:26:21AM +0100, Thomas Zimmermann wrote:
Mark screen buffers in system memory with FB_VIRTFB. Otherwise, the buffers are mmap'ed as I/O memory (i.e., VM_IO). For shadow buffers, also set the FB_READS_FAST hint.
Maybe clarify that this only holds for the defio case, and since we have our own shadow copy for that anyway it shouldn't matter. I'm also not sure how much the memcpy gains us compared to just redrawing ...
What's the motivation here, or just something you spotted?
Correctness mostly. fbdev's fbdefio tests for (the absence of) this flag and sets VM_IO accordingly.
It's actually for userspace. Maybe userspace tests these flags as well and can optimize memcpy pattern for different types of caching. But I wouldn't expect it TBH.
Best regards Thomas
-Daniel
Signed-off-by: Thomas Zimmermann tzimmermann@suse.de
drivers/gpu/drm/drm_fb_helper.c | 9 ++++++--- 1 file changed, 6 insertions(+), 3 deletions(-)
diff --git a/drivers/gpu/drm/drm_fb_helper.c b/drivers/gpu/drm/drm_fb_helper.c index ed43b987d306..f15127a32f7a 100644 --- a/drivers/gpu/drm/drm_fb_helper.c +++ b/drivers/gpu/drm/drm_fb_helper.c @@ -2346,6 +2346,7 @@ static int drm_fb_helper_generic_probe(struct drm_fb_helper *fb_helper, fbi->fbops = &drm_fbdev_fb_ops; fbi->screen_size = sizes->surface_height * fb->pitches[0]; fbi->fix.smem_len = fbi->screen_size;
fbi->flags = FBINFO_DEFAULT;
drm_fb_helper_fill_info(fbi, fb_helper, sizes);
@@ -2353,19 +2354,21 @@ static int drm_fb_helper_generic_probe(struct drm_fb_helper *fb_helper, fbi->screen_buffer = vzalloc(fbi->screen_size); if (!fbi->screen_buffer) return -ENOMEM;
fbi->flags |= FBINFO_VIRTFB | FBINFO_READS_FAST;fbi->fbdefio = &drm_fbdev_defio;
- fb_deferred_io_init(fbi); } else { /* buffer is mapped for HW framebuffer */ ret = drm_client_buffer_vmap(fb_helper->buffer, &map); if (ret) return ret;
if (map.is_iomem)
if (map.is_iomem) { fbi->screen_base = map.vaddr_iomem;
else
} else { fbi->screen_buffer = map.vaddr;fbi->flags |= FBINFO_VIRTFB;}/*
- Shamelessly leak the physical address to user-space. As
-- 2.34.1
On Thu, Jan 27, 2022 at 12:58:30PM +0100, Thomas Zimmermann wrote:
Hi
Am 27.01.22 um 12:42 schrieb Daniel Vetter:
On Thu, Jan 27, 2022 at 11:26:21AM +0100, Thomas Zimmermann wrote:
Mark screen buffers in system memory with FB_VIRTFB. Otherwise, the buffers are mmap'ed as I/O memory (i.e., VM_IO). For shadow buffers, also set the FB_READS_FAST hint.
Maybe clarify that this only holds for the defio case, and since we have our own shadow copy for that anyway it shouldn't matter. I'm also not sure how much the memcpy gains us compared to just redrawing ...
What's the motivation here, or just something you spotted?
Correctness mostly. fbdev's fbdefio tests for (the absence of) this flag and sets VM_IO accordingly.
It's actually for userspace. Maybe userspace tests these flags as well and can optimize memcpy pattern for different types of caching. But I wouldn't expect it TBH.
Hm I thought so too, but the #define is in the internal header, not the uapi header. And I don't see any ioctl code in fbmem.c that would shove fb_info->flags to userspace. That's why I wondered why you care about this? Or did I miss something somewhere? -Daniel
Best regards Thomas
-Daniel
Signed-off-by: Thomas Zimmermann tzimmermann@suse.de
drivers/gpu/drm/drm_fb_helper.c | 9 ++++++--- 1 file changed, 6 insertions(+), 3 deletions(-)
diff --git a/drivers/gpu/drm/drm_fb_helper.c b/drivers/gpu/drm/drm_fb_helper.c index ed43b987d306..f15127a32f7a 100644 --- a/drivers/gpu/drm/drm_fb_helper.c +++ b/drivers/gpu/drm/drm_fb_helper.c @@ -2346,6 +2346,7 @@ static int drm_fb_helper_generic_probe(struct drm_fb_helper *fb_helper, fbi->fbops = &drm_fbdev_fb_ops; fbi->screen_size = sizes->surface_height * fb->pitches[0]; fbi->fix.smem_len = fbi->screen_size;
- fbi->flags = FBINFO_DEFAULT; drm_fb_helper_fill_info(fbi, fb_helper, sizes);
@@ -2353,19 +2354,21 @@ static int drm_fb_helper_generic_probe(struct drm_fb_helper *fb_helper, fbi->screen_buffer = vzalloc(fbi->screen_size); if (!fbi->screen_buffer) return -ENOMEM;
fbi->flags |= FBINFO_VIRTFB | FBINFO_READS_FAST;
- fb_deferred_io_init(fbi); } else { /* buffer is mapped for HW framebuffer */ ret = drm_client_buffer_vmap(fb_helper->buffer, &map); if (ret) return ret;
if (map.is_iomem)
if (map.is_iomem) { fbi->screen_base = map.vaddr_iomem;
else
} else { fbi->screen_buffer = map.vaddr;fbi->flags |= FBINFO_VIRTFB;}
- Shamelessly leak the physical address to user-space. As
-- 2.34.1
-- Thomas Zimmermann Graphics Driver Developer SUSE Software Solutions Germany GmbH Maxfeldstr. 5, 90409 Nürnberg, Germany (HRB 36809, AG Nürnberg) Geschäftsführer: Ivo Totev
Hi
Am 27.01.22 um 16:03 schrieb Daniel Vetter:
On Thu, Jan 27, 2022 at 12:58:30PM +0100, Thomas Zimmermann wrote:
Hi
Am 27.01.22 um 12:42 schrieb Daniel Vetter:
On Thu, Jan 27, 2022 at 11:26:21AM +0100, Thomas Zimmermann wrote:
Mark screen buffers in system memory with FB_VIRTFB. Otherwise, the buffers are mmap'ed as I/O memory (i.e., VM_IO). For shadow buffers, also set the FB_READS_FAST hint.
Maybe clarify that this only holds for the defio case, and since we have our own shadow copy for that anyway it shouldn't matter. I'm also not sure how much the memcpy gains us compared to just redrawing ...
What's the motivation here, or just something you spotted?
Correctness mostly. fbdev's fbdefio tests for (the absence of) this flag and sets VM_IO accordingly.
It's actually for userspace. Maybe userspace tests these flags as well and can optimize memcpy pattern for different types of caching. But I wouldn't expect it TBH.
Hm I thought so too, but the #define is in the internal header, not the uapi header. And I don't see any ioctl code in fbmem.c that would shove fb_info->flags to userspace. That's why I wondered why you care about this? Or did I miss something somewhere?
You didn't. I just grepped it myself and the only user of VIRTFB is the mmap code in fb_deferio.c, which (not) sets VM_IO. READS_FAST is unused. I'd then set the former, but not the latter. Ok?
Best regards Thomas
-Daniel
Best regards Thomas
-Daniel
Signed-off-by: Thomas Zimmermann tzimmermann@suse.de
drivers/gpu/drm/drm_fb_helper.c | 9 ++++++--- 1 file changed, 6 insertions(+), 3 deletions(-)
diff --git a/drivers/gpu/drm/drm_fb_helper.c b/drivers/gpu/drm/drm_fb_helper.c index ed43b987d306..f15127a32f7a 100644 --- a/drivers/gpu/drm/drm_fb_helper.c +++ b/drivers/gpu/drm/drm_fb_helper.c @@ -2346,6 +2346,7 @@ static int drm_fb_helper_generic_probe(struct drm_fb_helper *fb_helper, fbi->fbops = &drm_fbdev_fb_ops; fbi->screen_size = sizes->surface_height * fb->pitches[0]; fbi->fix.smem_len = fbi->screen_size;
- fbi->flags = FBINFO_DEFAULT; drm_fb_helper_fill_info(fbi, fb_helper, sizes);
@@ -2353,19 +2354,21 @@ static int drm_fb_helper_generic_probe(struct drm_fb_helper *fb_helper, fbi->screen_buffer = vzalloc(fbi->screen_size); if (!fbi->screen_buffer) return -ENOMEM;
fbi->flags |= FBINFO_VIRTFB | FBINFO_READS_FAST; fbi->fbdefio = &drm_fbdev_defio;
fb_deferred_io_init(fbi);if (map.is_iomem)
if (map.is_iomem) { fbi->screen_base = map.vaddr_iomem;
else
} else { fbi->screen_buffer = map.vaddr;fbi->flags |= FBINFO_VIRTFB;} /* * Shamelessly leak the physical address to user-space. As-- 2.34.1
-- Thomas Zimmermann Graphics Driver Developer SUSE Software Solutions Germany GmbH Maxfeldstr. 5, 90409 Nürnberg, Germany (HRB 36809, AG Nürnberg) Geschäftsführer: Ivo Totev
On Thu, Jan 27, 2022 at 4:18 PM Thomas Zimmermann tzimmermann@suse.de wrote:
Hi
Am 27.01.22 um 16:03 schrieb Daniel Vetter:
On Thu, Jan 27, 2022 at 12:58:30PM +0100, Thomas Zimmermann wrote:
Hi
Am 27.01.22 um 12:42 schrieb Daniel Vetter:
On Thu, Jan 27, 2022 at 11:26:21AM +0100, Thomas Zimmermann wrote:
Mark screen buffers in system memory with FB_VIRTFB. Otherwise, the buffers are mmap'ed as I/O memory (i.e., VM_IO). For shadow buffers, also set the FB_READS_FAST hint.
Maybe clarify that this only holds for the defio case, and since we have our own shadow copy for that anyway it shouldn't matter. I'm also not sure how much the memcpy gains us compared to just redrawing ...
What's the motivation here, or just something you spotted?
Correctness mostly. fbdev's fbdefio tests for (the absence of) this flag and sets VM_IO accordingly.
It's actually for userspace. Maybe userspace tests these flags as well and can optimize memcpy pattern for different types of caching. But I wouldn't expect it TBH.
Hm I thought so too, but the #define is in the internal header, not the uapi header. And I don't see any ioctl code in fbmem.c that would shove fb_info->flags to userspace. That's why I wondered why you care about this? Or did I miss something somewhere?
You didn't. I just grepped it myself and the only user of VIRTFB is the mmap code in fb_deferio.c, which (not) sets VM_IO. READS_FAST is unused. I'd then set the former, but not the latter. Ok?
Well READS_FAST might become used again, if/when the accel code is back. So I'd more keep that part, and leave the VIRTFB one alone, since you never set that for the defio case. I'm also not sure how that even works, since defio relies on struct page being present underneath, and you defo don't have struct page for VM_IO cases. So it all looks rather fishy. Or I'm still massively misunderstanding it all? -Daniel
Best regards Thomas
-Daniel
Best regards Thomas
-Daniel
Signed-off-by: Thomas Zimmermann tzimmermann@suse.de
drivers/gpu/drm/drm_fb_helper.c | 9 ++++++--- 1 file changed, 6 insertions(+), 3 deletions(-)
diff --git a/drivers/gpu/drm/drm_fb_helper.c b/drivers/gpu/drm/drm_fb_helper.c index ed43b987d306..f15127a32f7a 100644 --- a/drivers/gpu/drm/drm_fb_helper.c +++ b/drivers/gpu/drm/drm_fb_helper.c @@ -2346,6 +2346,7 @@ static int drm_fb_helper_generic_probe(struct drm_fb_helper *fb_helper, fbi->fbops = &drm_fbdev_fb_ops; fbi->screen_size = sizes->surface_height * fb->pitches[0]; fbi->fix.smem_len = fbi->screen_size;
- fbi->flags = FBINFO_DEFAULT; drm_fb_helper_fill_info(fbi, fb_helper, sizes);
@@ -2353,19 +2354,21 @@ static int drm_fb_helper_generic_probe(struct drm_fb_helper *fb_helper, fbi->screen_buffer = vzalloc(fbi->screen_size); if (!fbi->screen_buffer) return -ENOMEM;
fbi->flags |= FBINFO_VIRTFB | FBINFO_READS_FAST; fbi->fbdefio = &drm_fbdev_defio;
fb_deferred_io_init(fbi); } else { /* buffer is mapped for HW framebuffer */ ret = drm_client_buffer_vmap(fb_helper->buffer, &map); if (ret) return ret;if (map.is_iomem)
if (map.is_iomem) { fbi->screen_base = map.vaddr_iomem;
else
} else { fbi->screen_buffer = map.vaddr;fbi->flags |= FBINFO_VIRTFB;} /* * Shamelessly leak the physical address to user-space. As-- 2.34.1
-- Thomas Zimmermann Graphics Driver Developer SUSE Software Solutions Germany GmbH Maxfeldstr. 5, 90409 Nürnberg, Germany (HRB 36809, AG Nürnberg) Geschäftsführer: Ivo Totev
-- Thomas Zimmermann Graphics Driver Developer SUSE Software Solutions Germany GmbH Maxfeldstr. 5, 90409 Nürnberg, Germany (HRB 36809, AG Nürnberg) Geschäftsführer: Ivo Totev
Hi
Am 28.01.22 um 12:00 schrieb Daniel Vetter:
On Thu, Jan 27, 2022 at 4:18 PM Thomas Zimmermann tzimmermann@suse.de wrote:
Hi
Am 27.01.22 um 16:03 schrieb Daniel Vetter:
On Thu, Jan 27, 2022 at 12:58:30PM +0100, Thomas Zimmermann wrote:
Hi
Am 27.01.22 um 12:42 schrieb Daniel Vetter:
On Thu, Jan 27, 2022 at 11:26:21AM +0100, Thomas Zimmermann wrote:
Mark screen buffers in system memory with FB_VIRTFB. Otherwise, the buffers are mmap'ed as I/O memory (i.e., VM_IO). For shadow buffers, also set the FB_READS_FAST hint.
Maybe clarify that this only holds for the defio case, and since we have our own shadow copy for that anyway it shouldn't matter. I'm also not sure how much the memcpy gains us compared to just redrawing ...
What's the motivation here, or just something you spotted?
Correctness mostly. fbdev's fbdefio tests for (the absence of) this flag and sets VM_IO accordingly.
It's actually for userspace. Maybe userspace tests these flags as well and can optimize memcpy pattern for different types of caching. But I wouldn't expect it TBH.
Hm I thought so too, but the #define is in the internal header, not the uapi header. And I don't see any ioctl code in fbmem.c that would shove fb_info->flags to userspace. That's why I wondered why you care about this? Or did I miss something somewhere?
You didn't. I just grepped it myself and the only user of VIRTFB is the mmap code in fb_deferio.c, which (not) sets VM_IO. READS_FAST is unused. I'd then set the former, but not the latter. Ok?
Well READS_FAST might become used again, if/when the accel code is
Ok.
back. So I'd more keep that part, and leave the VIRTFB one alone, since you never set that for the defio case. I'm also not sure how that even works, since defio relies on struct page being present underneath, and you defo don't have struct page for VM_IO cases. So it all looks rather fishy. Or I'm still massively misunderstanding it all?
We only set the VIRTFB flag if we use our internal shadow buffer, which is allocate via vzalloc() in drm_fb_helper_generic_probe(). Of course, the shadow buffer is regular memory and not an I/O range.
The fbdefio on this buffer is completely implemented by the fbdev susbystem, which uses pages (i.e., no VM_PFNMAP flag). See https://elixir.bootlin.com/linux/latest/source/drivers/video/fbdev/core/fb_d... for the respective mmap code. Our GEM code never even knows that an mmap call has taken place. It just sees the occasional damage updates that fbdevio generates. Setting VIRTFB on the shadow buffer's memory is the right thing to do IMHO.
Best regards Thomas
-Daniel
Best regards Thomas
-Daniel
Best regards Thomas
-Daniel
Signed-off-by: Thomas Zimmermann tzimmermann@suse.de
drivers/gpu/drm/drm_fb_helper.c | 9 ++++++--- 1 file changed, 6 insertions(+), 3 deletions(-)diff --git a/drivers/gpu/drm/drm_fb_helper.c b/drivers/gpu/drm/drm_fb_helper.c index ed43b987d306..f15127a32f7a 100644 --- a/drivers/gpu/drm/drm_fb_helper.c +++ b/drivers/gpu/drm/drm_fb_helper.c @@ -2346,6 +2346,7 @@ static int drm_fb_helper_generic_probe(struct drm_fb_helper *fb_helper, fbi->fbops = &drm_fbdev_fb_ops; fbi->screen_size = sizes->surface_height * fb->pitches[0]; fbi->fix.smem_len = fbi->screen_size;
- fbi->flags = FBINFO_DEFAULT; drm_fb_helper_fill_info(fbi, fb_helper, sizes);
@@ -2353,19 +2354,21 @@ static int drm_fb_helper_generic_probe(struct drm_fb_helper *fb_helper, fbi->screen_buffer = vzalloc(fbi->screen_size); if (!fbi->screen_buffer) return -ENOMEM;
fbi->flags |= FBINFO_VIRTFB | FBINFO_READS_FAST; fbi->fbdefio = &drm_fbdev_defio;
fb_deferred_io_init(fbi); } else { /* buffer is mapped for HW framebuffer */ ret = drm_client_buffer_vmap(fb_helper->buffer, &map); if (ret) return ret;if (map.is_iomem)
if (map.is_iomem) { fbi->screen_base = map.vaddr_iomem;
else
} else { fbi->screen_buffer = map.vaddr;fbi->flags |= FBINFO_VIRTFB;} /* * Shamelessly leak the physical address to user-space. As-- 2.34.1
-- Thomas Zimmermann Graphics Driver Developer SUSE Software Solutions Germany GmbH Maxfeldstr. 5, 90409 Nürnberg, Germany (HRB 36809, AG Nürnberg) Geschäftsführer: Ivo Totev
-- Thomas Zimmermann Graphics Driver Developer SUSE Software Solutions Germany GmbH Maxfeldstr. 5, 90409 Nürnberg, Germany (HRB 36809, AG Nürnberg) Geschäftsführer: Ivo Totev
On Fri, Jan 28, 2022 at 12:36 PM Thomas Zimmermann tzimmermann@suse.de wrote:
Hi
Am 28.01.22 um 12:00 schrieb Daniel Vetter:
On Thu, Jan 27, 2022 at 4:18 PM Thomas Zimmermann tzimmermann@suse.de wrote:
Hi
Am 27.01.22 um 16:03 schrieb Daniel Vetter:
On Thu, Jan 27, 2022 at 12:58:30PM +0100, Thomas Zimmermann wrote:
Hi
Am 27.01.22 um 12:42 schrieb Daniel Vetter:
On Thu, Jan 27, 2022 at 11:26:21AM +0100, Thomas Zimmermann wrote: > Mark screen buffers in system memory with FB_VIRTFB. Otherwise, the > buffers are mmap'ed as I/O memory (i.e., VM_IO). For shadow buffers, > also set the FB_READS_FAST hint.
Maybe clarify that this only holds for the defio case, and since we have our own shadow copy for that anyway it shouldn't matter. I'm also not sure how much the memcpy gains us compared to just redrawing ...
What's the motivation here, or just something you spotted?
Correctness mostly. fbdev's fbdefio tests for (the absence of) this flag and sets VM_IO accordingly.
It's actually for userspace. Maybe userspace tests these flags as well and can optimize memcpy pattern for different types of caching. But I wouldn't expect it TBH.
Hm I thought so too, but the #define is in the internal header, not the uapi header. And I don't see any ioctl code in fbmem.c that would shove fb_info->flags to userspace. That's why I wondered why you care about this? Or did I miss something somewhere?
You didn't. I just grepped it myself and the only user of VIRTFB is the mmap code in fb_deferio.c, which (not) sets VM_IO. READS_FAST is unused. I'd then set the former, but not the latter. Ok?
Well READS_FAST might become used again, if/when the accel code is
Ok.
back. So I'd more keep that part, and leave the VIRTFB one alone, since you never set that for the defio case. I'm also not sure how that even works, since defio relies on struct page being present underneath, and you defo don't have struct page for VM_IO cases. So it all looks rather fishy. Or I'm still massively misunderstanding it all?
We only set the VIRTFB flag if we use our internal shadow buffer, which is allocate via vzalloc() in drm_fb_helper_generic_probe(). Of course, the shadow buffer is regular memory and not an I/O range.
The fbdefio on this buffer is completely implemented by the fbdev susbystem, which uses pages (i.e., no VM_PFNMAP flag). See https://elixir.bootlin.com/linux/latest/source/drivers/video/fbdev/core/fb_d... for the respective mmap code. Our GEM code never even knows that an mmap call has taken place. It just sees the occasional damage updates that fbdevio generates. Setting VIRTFB on the shadow buffer's memory is the right thing to do IMHO.
Oh dear I read that test inverted and thought if we do nothing, then we wouldn't get VM_IO. Imo if you explain this in the commit message (and maybe in a comment like "make sure defio mmap does not set VM_IO" then this has my Reviewed-by: Daniel Vetter daniel.vetter@ffwll.ch Also I guess this should have a cc: stable since I guess without it it'll go boom on a bunch of the more obscure architectures ...
I'm not sure the 2nd part that sets VIRTFB for other parts makes sense since mmap is fully under our control for that case. Imo drop it, but also I'm ok if you keep it.
Also I guess yet another reason to just pull the defio stuff into our fbdev emulation layer, because we're just fighting a questionable midlayer here :-) -Daniel
Best regards Thomas
-Daniel
Best regards Thomas
-Daniel
Best regards Thomas
-Daniel
> > Signed-off-by: Thomas Zimmermann tzimmermann@suse.de > --- > drivers/gpu/drm/drm_fb_helper.c | 9 ++++++--- > 1 file changed, 6 insertions(+), 3 deletions(-) > > diff --git a/drivers/gpu/drm/drm_fb_helper.c b/drivers/gpu/drm/drm_fb_helper.c > index ed43b987d306..f15127a32f7a 100644 > --- a/drivers/gpu/drm/drm_fb_helper.c > +++ b/drivers/gpu/drm/drm_fb_helper.c > @@ -2346,6 +2346,7 @@ static int drm_fb_helper_generic_probe(struct drm_fb_helper *fb_helper, > fbi->fbops = &drm_fbdev_fb_ops; > fbi->screen_size = sizes->surface_height * fb->pitches[0]; > fbi->fix.smem_len = fbi->screen_size; > + fbi->flags = FBINFO_DEFAULT; > drm_fb_helper_fill_info(fbi, fb_helper, sizes); > @@ -2353,19 +2354,21 @@ static int drm_fb_helper_generic_probe(struct drm_fb_helper *fb_helper, > fbi->screen_buffer = vzalloc(fbi->screen_size); > if (!fbi->screen_buffer) > return -ENOMEM; > + fbi->flags |= FBINFO_VIRTFB | FBINFO_READS_FAST; > fbi->fbdefio = &drm_fbdev_defio; > - > fb_deferred_io_init(fbi); > } else { > /* buffer is mapped for HW framebuffer */ > ret = drm_client_buffer_vmap(fb_helper->buffer, &map); > if (ret) > return ret; > - if (map.is_iomem) > + if (map.is_iomem) { > fbi->screen_base = map.vaddr_iomem; > - else > + } else { > fbi->screen_buffer = map.vaddr; > + fbi->flags |= FBINFO_VIRTFB; > + } > /* > * Shamelessly leak the physical address to user-space. As > -- > 2.34.1 >
-- Thomas Zimmermann Graphics Driver Developer SUSE Software Solutions Germany GmbH Maxfeldstr. 5, 90409 Nürnberg, Germany (HRB 36809, AG Nürnberg) Geschäftsführer: Ivo Totev
-- Thomas Zimmermann Graphics Driver Developer SUSE Software Solutions Germany GmbH Maxfeldstr. 5, 90409 Nürnberg, Germany (HRB 36809, AG Nürnberg) Geschäftsführer: Ivo Totev
-- Thomas Zimmermann Graphics Driver Developer SUSE Software Solutions Germany GmbH Maxfeldstr. 5, 90409 Nürnberg, Germany (HRB 36809, AG Nürnberg) Geschäftsführer: Ivo Totev
dri-devel@lists.freedesktop.org
-
Daniel Vetter -
Thomas Zimmermann