Re: [Intel-gfx] [PATCH v5 4/5] drm: Add library for shmem backed GEM objects
Den 29.01.2019 01.19, skrev Eric Anholt:
> Noralf Trønnes writes:
>
>> Den 28.01.2019 21.57, skrev Rob Herring:
>>> On Sun, Dec 2, 2018 at 9:59 AM Noralf Trønnes wrote:
Den 30.11.2018 00.58, skrev Eric Anholt:
> Daniel Vetter writes:
>
>> On Wed, Nov 28, 2018 at 01:52:56PM -0800, Eric Anholt wrote:
>>> Daniel Vetter writes:
>>>
On Tue, Nov 27, 2018 at 12:38:44PM -0800, Eric Anholt wrote:
> Daniel Vetter writes:
>
>> On Mon, Nov 26, 2018 at 04:36:21PM -0800, Eric Anholt wrote:
>>> Noralf Trønnes writes:
+static void drm_gem_shmem_vm_close(struct vm_area_struct *vma)
+{
+ struct drm_gem_object *obj = vma->vm_private_data;
+ struct drm_gem_shmem_object *shmem =
to_drm_gem_shmem_obj(obj);
+
+ drm_gem_shmem_put_pages(shmem);
+ drm_gem_vm_close(vma);
+}
+
+const struct vm_operations_struct drm_gem_shmem_vm_ops = {
+ .fault = drm_gem_shmem_fault,
+ .open = drm_gem_vm_open,
+ .close = drm_gem_shmem_vm_close,
+};
+EXPORT_SYMBOL_GPL(drm_gem_shmem_vm_ops);
>>> I just saw a warning from drm_gem_shmem_put_pages() for
>>> !shmem->pages_use_count -- I think drm_gem_vm_open() needs to
>>> drm_gem_shmem_get_pages().
>> Yeah we need a drm_gem_shmem_vm_open here.
> Adding one of those fixed my refcounting issues, so I've sent out a v6
> with it.
Just realized that I've reviewed this patch already, spotted that vma
management issue there too. Plus a pile of other things. From reading
that
other thread discussion with Noralf concluded with "not yet ready for
prime time" unfortunately :-/
>>> I saw stuff about how it wasn't usable for SPI because SPI does weird
>>> things with DMA mapping. Was there something else?
>> Looking through that mail it was a bunch of comments to improve the
>> kerneldoc. Plus a note that buffer sharing/mmap is going to be all
>> incoherent and horrible (but I guess for vkms we don't care that much).
>> I'm just kinda vary of generic buffer handling that turns out to not be
>> actually all that useful. We have lots of deadends and kinda-midlayers in
>> this area already (but this one here definitely smells plenty better than
>> lots of older ones).
> FWIW, I really want shmem helpers for v3d. The fault handling in
> particular has magic I don't understand, and this is not my first fault
> handler. :/
If you can use it for a "real" hw driver like v3d, I think it makes a lot
sense to have it as a helper. I believe udl and a future simpledrm can
also make use of it.
>>>
>>> FWIW, I think etnaviv at least could use this too.
>>>
>>> I'm starting to look at panfrost and lima drivers and was trying to
>>> figure out where to start with the GEM code. So I've been comparing
>>> etnaviv, freedreno, and vgem implementations. They are all pretty
>>> similar from what I see. The per driver GEM obj structs certainly are.
>>> I can't bring myself to just copy etnaviv code over and do a
>>> s/etnaviv/panfrost/. So searching around a bit, I ended up on this
>>> thread. This seems to be what I need for panfrost (based on my brief
>>> study).
>>>
>>
>> I gave up on this due to problems with SPI DMA.
>> Eric tried to use it with vkms, but it failed. On his blog he speculates
>> that it might be due to cached CPU mappings:
>> https://anholt.github.io/twivc4/2018/12/03/twiv/
>>
>> For tinydrm I wanted cached mappings, but it might not work that well
>> with shmem. Maybe that's why I had problems with SPI DMA.
>
> Actually, for tinydrm buffers that are dma-buf exported through prime, I
> really want tinydrm using WC mappings so that vc4 or v3d rendering (now
> supported on Mesa master with kmsro) works.
>
I thought that the buffer is created by the GPU driver when using PRIME?
And them imported into the tinydrm driver. In which case it doesn't
matter how tinydrm creates it's dumb buffers.
That said, I will stay with CMA buffers for the SPI drivers. It just
works. The reason I looked into shmem, is that tindyrm would then be
able to import buffers that isn't contiguous in memory, thus making it
work with more GPU's. And the reason for cached buffers is that with
partial flushing the rectangle is copied to a separate buffer for
transfer and CPU acccess to WC memory is quite slow. But ofc for these
small buffers it's not that big a deal.
Noralf.
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Re: [Intel-gfx] [PATCH v5 4/5] drm: Add library for shmem backed GEM objects
Noralf Trønnes writes:
> Den 28.01.2019 21.57, skrev Rob Herring:
>> On Sun, Dec 2, 2018 at 9:59 AM Noralf Trønnes wrote:
>>>
>>>
>>> Den 30.11.2018 00.58, skrev Eric Anholt:
Daniel Vetter writes:
> On Wed, Nov 28, 2018 at 01:52:56PM -0800, Eric Anholt wrote:
>> Daniel Vetter writes:
>>
>>> On Tue, Nov 27, 2018 at 12:38:44PM -0800, Eric Anholt wrote:
Daniel Vetter writes:
> On Mon, Nov 26, 2018 at 04:36:21PM -0800, Eric Anholt wrote:
>> Noralf Trønnes writes:
>>> +static void drm_gem_shmem_vm_close(struct vm_area_struct *vma)
>>> +{
>>> + struct drm_gem_object *obj = vma->vm_private_data;
>>> + struct drm_gem_shmem_object *shmem =
>>> to_drm_gem_shmem_obj(obj);
>>> +
>>> + drm_gem_shmem_put_pages(shmem);
>>> + drm_gem_vm_close(vma);
>>> +}
>>> +
>>> +const struct vm_operations_struct drm_gem_shmem_vm_ops = {
>>> + .fault = drm_gem_shmem_fault,
>>> + .open = drm_gem_vm_open,
>>> + .close = drm_gem_shmem_vm_close,
>>> +};
>>> +EXPORT_SYMBOL_GPL(drm_gem_shmem_vm_ops);
>> I just saw a warning from drm_gem_shmem_put_pages() for
>> !shmem->pages_use_count -- I think drm_gem_vm_open() needs to
>> drm_gem_shmem_get_pages().
> Yeah we need a drm_gem_shmem_vm_open here.
Adding one of those fixed my refcounting issues, so I've sent out a v6
with it.
>>> Just realized that I've reviewed this patch already, spotted that vma
>>> management issue there too. Plus a pile of other things. From reading
>>> that
>>> other thread discussion with Noralf concluded with "not yet ready for
>>> prime time" unfortunately :-/
>> I saw stuff about how it wasn't usable for SPI because SPI does weird
>> things with DMA mapping. Was there something else?
> Looking through that mail it was a bunch of comments to improve the
> kerneldoc. Plus a note that buffer sharing/mmap is going to be all
> incoherent and horrible (but I guess for vkms we don't care that much).
> I'm just kinda vary of generic buffer handling that turns out to not be
> actually all that useful. We have lots of deadends and kinda-midlayers in
> this area already (but this one here definitely smells plenty better than
> lots of older ones).
FWIW, I really want shmem helpers for v3d. The fault handling in
particular has magic I don't understand, and this is not my first fault
handler. :/
>>>
>>>
>>> If you can use it for a "real" hw driver like v3d, I think it makes a lot
>>> sense to have it as a helper. I believe udl and a future simpledrm can
>>> also make use of it.
>>
>> FWIW, I think etnaviv at least could use this too.
>>
>> I'm starting to look at panfrost and lima drivers and was trying to
>> figure out where to start with the GEM code. So I've been comparing
>> etnaviv, freedreno, and vgem implementations. They are all pretty
>> similar from what I see. The per driver GEM obj structs certainly are.
>> I can't bring myself to just copy etnaviv code over and do a
>> s/etnaviv/panfrost/. So searching around a bit, I ended up on this
>> thread. This seems to be what I need for panfrost (based on my brief
>> study).
>>
>
> I gave up on this due to problems with SPI DMA.
> Eric tried to use it with vkms, but it failed. On his blog he speculates
> that it might be due to cached CPU mappings:
> https://anholt.github.io/twivc4/2018/12/03/twiv/
>
> For tinydrm I wanted cached mappings, but it might not work that well
> with shmem. Maybe that's why I had problems with SPI DMA.
Actually, for tinydrm buffers that are dma-buf exported through prime, I
really want tinydrm using WC mappings so that vc4 or v3d rendering (now
supported on Mesa master with kmsro) works.
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Re: [Intel-gfx] [PATCH v5 4/5] drm: Add library for shmem backed GEM objects
On Mon, Jan 28, 2019 at 3:26 PM Noralf Trønnes wrote:
>
>
>
> Den 28.01.2019 21.57, skrev Rob Herring:
> > On Sun, Dec 2, 2018 at 9:59 AM Noralf Trønnes wrote:
> >>
> >>
> >> Den 30.11.2018 00.58, skrev Eric Anholt:
> >>> Daniel Vetter writes:
> >>>
> On Wed, Nov 28, 2018 at 01:52:56PM -0800, Eric Anholt wrote:
> > Daniel Vetter writes:
> >
> >> On Tue, Nov 27, 2018 at 12:38:44PM -0800, Eric Anholt wrote:
> >>> Daniel Vetter writes:
> >>>
> On Mon, Nov 26, 2018 at 04:36:21PM -0800, Eric Anholt wrote:
> > Noralf Trønnes writes:
> >> +static void drm_gem_shmem_vm_close(struct vm_area_struct *vma)
> >> +{
> >> + struct drm_gem_object *obj = vma->vm_private_data;
> >> + struct drm_gem_shmem_object *shmem =
> >> to_drm_gem_shmem_obj(obj);
> >> +
> >> + drm_gem_shmem_put_pages(shmem);
> >> + drm_gem_vm_close(vma);
> >> +}
> >> +
> >> +const struct vm_operations_struct drm_gem_shmem_vm_ops = {
> >> + .fault = drm_gem_shmem_fault,
> >> + .open = drm_gem_vm_open,
> >> + .close = drm_gem_shmem_vm_close,
> >> +};
> >> +EXPORT_SYMBOL_GPL(drm_gem_shmem_vm_ops);
> > I just saw a warning from drm_gem_shmem_put_pages() for
> > !shmem->pages_use_count -- I think drm_gem_vm_open() needs to
> > drm_gem_shmem_get_pages().
> Yeah we need a drm_gem_shmem_vm_open here.
> >>> Adding one of those fixed my refcounting issues, so I've sent out a v6
> >>> with it.
> >> Just realized that I've reviewed this patch already, spotted that vma
> >> management issue there too. Plus a pile of other things. From reading
> >> that
> >> other thread discussion with Noralf concluded with "not yet ready for
> >> prime time" unfortunately :-/
> > I saw stuff about how it wasn't usable for SPI because SPI does weird
> > things with DMA mapping. Was there something else?
> Looking through that mail it was a bunch of comments to improve the
> kerneldoc. Plus a note that buffer sharing/mmap is going to be all
> incoherent and horrible (but I guess for vkms we don't care that much).
> I'm just kinda vary of generic buffer handling that turns out to not be
> actually all that useful. We have lots of deadends and kinda-midlayers in
> this area already (but this one here definitely smells plenty better than
> lots of older ones).
> >>> FWIW, I really want shmem helpers for v3d. The fault handling in
> >>> particular has magic I don't understand, and this is not my first fault
> >>> handler. :/
> >>
> >>
> >> If you can use it for a "real" hw driver like v3d, I think it makes a lot
> >> sense to have it as a helper. I believe udl and a future simpledrm can
> >> also make use of it.
> >
> > FWIW, I think etnaviv at least could use this too.
> >
> > I'm starting to look at panfrost and lima drivers and was trying to
> > figure out where to start with the GEM code. So I've been comparing
> > etnaviv, freedreno, and vgem implementations. They are all pretty
> > similar from what I see. The per driver GEM obj structs certainly are.
> > I can't bring myself to just copy etnaviv code over and do a
> > s/etnaviv/panfrost/. So searching around a bit, I ended up on this
> > thread. This seems to be what I need for panfrost (based on my brief
> > study).
> >
>
> I gave up on this due to problems with SPI DMA.
> Eric tried to use it with vkms, but it failed. On his blog he speculates
> that it might be due to cached CPU mappings:
> https://anholt.github.io/twivc4/2018/12/03/twiv/
>
> For tinydrm I wanted cached mappings, but it might not work that well
> with shmem. Maybe that's why I had problems with SPI DMA.
I think for most ARM systems, a cached mapping is not coherent. So
there will need to be cache flushes using the dma API. I see there's
been some discussion around that too.
> Maybe this change to drm_gem_shmem_mmap() is all it takes:
>
> - vma->vm_page_prot = vm_get_page_prot(vma->vm_flags);
> + vma->vm_page_prot =
> pgprot_writecombine(vm_get_page_prot(vma->vm_flags));
Seems like at least this part needs some flexibility. etnaviv,
freedreno, and omap at least all appear to support cached, uncached,
and writecombined based on flags in the GEM object.
> The memory subsystem is really complicated and I have kind of given up
> on trying to decipher it.
Yes. All the more reason to not let each driver figure out what to do.
Rob
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Re: [Intel-gfx] [PATCH v5 4/5] drm: Add library for shmem backed GEM objects
Den 28.01.2019 21.57, skrev Rob Herring:
> On Sun, Dec 2, 2018 at 9:59 AM Noralf Trønnes wrote:
>>
>>
>> Den 30.11.2018 00.58, skrev Eric Anholt:
>>> Daniel Vetter writes:
>>>
On Wed, Nov 28, 2018 at 01:52:56PM -0800, Eric Anholt wrote:
> Daniel Vetter writes:
>
>> On Tue, Nov 27, 2018 at 12:38:44PM -0800, Eric Anholt wrote:
>>> Daniel Vetter writes:
>>>
On Mon, Nov 26, 2018 at 04:36:21PM -0800, Eric Anholt wrote:
> Noralf Trønnes writes:
>> +static void drm_gem_shmem_vm_close(struct vm_area_struct *vma)
>> +{
>> + struct drm_gem_object *obj = vma->vm_private_data;
>> + struct drm_gem_shmem_object *shmem =
>> to_drm_gem_shmem_obj(obj);
>> +
>> + drm_gem_shmem_put_pages(shmem);
>> + drm_gem_vm_close(vma);
>> +}
>> +
>> +const struct vm_operations_struct drm_gem_shmem_vm_ops = {
>> + .fault = drm_gem_shmem_fault,
>> + .open = drm_gem_vm_open,
>> + .close = drm_gem_shmem_vm_close,
>> +};
>> +EXPORT_SYMBOL_GPL(drm_gem_shmem_vm_ops);
> I just saw a warning from drm_gem_shmem_put_pages() for
> !shmem->pages_use_count -- I think drm_gem_vm_open() needs to
> drm_gem_shmem_get_pages().
Yeah we need a drm_gem_shmem_vm_open here.
>>> Adding one of those fixed my refcounting issues, so I've sent out a v6
>>> with it.
>> Just realized that I've reviewed this patch already, spotted that vma
>> management issue there too. Plus a pile of other things. From reading
>> that
>> other thread discussion with Noralf concluded with "not yet ready for
>> prime time" unfortunately :-/
> I saw stuff about how it wasn't usable for SPI because SPI does weird
> things with DMA mapping. Was there something else?
Looking through that mail it was a bunch of comments to improve the
kerneldoc. Plus a note that buffer sharing/mmap is going to be all
incoherent and horrible (but I guess for vkms we don't care that much).
I'm just kinda vary of generic buffer handling that turns out to not be
actually all that useful. We have lots of deadends and kinda-midlayers in
this area already (but this one here definitely smells plenty better than
lots of older ones).
>>> FWIW, I really want shmem helpers for v3d. The fault handling in
>>> particular has magic I don't understand, and this is not my first fault
>>> handler. :/
>>
>>
>> If you can use it for a "real" hw driver like v3d, I think it makes a lot
>> sense to have it as a helper. I believe udl and a future simpledrm can
>> also make use of it.
>
> FWIW, I think etnaviv at least could use this too.
>
> I'm starting to look at panfrost and lima drivers and was trying to
> figure out where to start with the GEM code. So I've been comparing
> etnaviv, freedreno, and vgem implementations. They are all pretty
> similar from what I see. The per driver GEM obj structs certainly are.
> I can't bring myself to just copy etnaviv code over and do a
> s/etnaviv/panfrost/. So searching around a bit, I ended up on this
> thread. This seems to be what I need for panfrost (based on my brief
> study).
>
I gave up on this due to problems with SPI DMA.
Eric tried to use it with vkms, but it failed. On his blog he speculates
that it might be due to cached CPU mappings:
https://anholt.github.io/twivc4/2018/12/03/twiv/
For tinydrm I wanted cached mappings, but it might not work that well
with shmem. Maybe that's why I had problems with SPI DMA.
Maybe this change to drm_gem_shmem_mmap() is all it takes:
- vma->vm_page_prot = vm_get_page_prot(vma->vm_flags);
+ vma->vm_page_prot =
pgprot_writecombine(vm_get_page_prot(vma->vm_flags));
The memory subsystem is really complicated and I have kind of given up
on trying to decipher it.
Noralf.
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Re: [Intel-gfx] [PATCH v5 4/5] drm: Add library for shmem backed GEM objects
On Sun, Dec 2, 2018 at 9:59 AM Noralf Trønnes wrote:
>
>
> Den 30.11.2018 00.58, skrev Eric Anholt:
> > Daniel Vetter writes:
> >
> >> On Wed, Nov 28, 2018 at 01:52:56PM -0800, Eric Anholt wrote:
> >>> Daniel Vetter writes:
> >>>
> On Tue, Nov 27, 2018 at 12:38:44PM -0800, Eric Anholt wrote:
> > Daniel Vetter writes:
> >
> >> On Mon, Nov 26, 2018 at 04:36:21PM -0800, Eric Anholt wrote:
> >>> Noralf Trønnes writes:
> +static void drm_gem_shmem_vm_close(struct vm_area_struct *vma)
> +{
> + struct drm_gem_object *obj = vma->vm_private_data;
> + struct drm_gem_shmem_object *shmem =
> to_drm_gem_shmem_obj(obj);
> +
> + drm_gem_shmem_put_pages(shmem);
> + drm_gem_vm_close(vma);
> +}
> +
> +const struct vm_operations_struct drm_gem_shmem_vm_ops = {
> + .fault = drm_gem_shmem_fault,
> + .open = drm_gem_vm_open,
> + .close = drm_gem_shmem_vm_close,
> +};
> +EXPORT_SYMBOL_GPL(drm_gem_shmem_vm_ops);
> >>> I just saw a warning from drm_gem_shmem_put_pages() for
> >>> !shmem->pages_use_count -- I think drm_gem_vm_open() needs to
> >>> drm_gem_shmem_get_pages().
> >> Yeah we need a drm_gem_shmem_vm_open here.
> > Adding one of those fixed my refcounting issues, so I've sent out a v6
> > with it.
> Just realized that I've reviewed this patch already, spotted that vma
> management issue there too. Plus a pile of other things. From reading
> that
> other thread discussion with Noralf concluded with "not yet ready for
> prime time" unfortunately :-/
> >>> I saw stuff about how it wasn't usable for SPI because SPI does weird
> >>> things with DMA mapping. Was there something else?
> >> Looking through that mail it was a bunch of comments to improve the
> >> kerneldoc. Plus a note that buffer sharing/mmap is going to be all
> >> incoherent and horrible (but I guess for vkms we don't care that much).
> >> I'm just kinda vary of generic buffer handling that turns out to not be
> >> actually all that useful. We have lots of deadends and kinda-midlayers in
> >> this area already (but this one here definitely smells plenty better than
> >> lots of older ones).
> > FWIW, I really want shmem helpers for v3d. The fault handling in
> > particular has magic I don't understand, and this is not my first fault
> > handler. :/
>
>
> If you can use it for a "real" hw driver like v3d, I think it makes a lot
> sense to have it as a helper. I believe udl and a future simpledrm can
> also make use of it.
FWIW, I think etnaviv at least could use this too.
I'm starting to look at panfrost and lima drivers and was trying to
figure out where to start with the GEM code. So I've been comparing
etnaviv, freedreno, and vgem implementations. They are all pretty
similar from what I see. The per driver GEM obj structs certainly are.
I can't bring myself to just copy etnaviv code over and do a
s/etnaviv/panfrost/. So searching around a bit, I ended up on this
thread. This seems to be what I need for panfrost (based on my brief
study).
Rob
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Re: [Intel-gfx] [PATCH v5 4/5] drm: Add library for shmem backed GEM objects
Den 30.11.2018 00.58, skrev Eric Anholt:
Daniel Vetter writes:
On Wed, Nov 28, 2018 at 01:52:56PM -0800, Eric Anholt wrote:
Daniel Vetter writes:
On Tue, Nov 27, 2018 at 12:38:44PM -0800, Eric Anholt wrote:
Daniel Vetter writes:
On Mon, Nov 26, 2018 at 04:36:21PM -0800, Eric Anholt wrote:
Noralf Trønnes writes:
+static void drm_gem_shmem_vm_close(struct vm_area_struct *vma)
+{
+ struct drm_gem_object *obj = vma->vm_private_data;
+ struct drm_gem_shmem_object *shmem = to_drm_gem_shmem_obj(obj);
+
+ drm_gem_shmem_put_pages(shmem);
+ drm_gem_vm_close(vma);
+}
+
+const struct vm_operations_struct drm_gem_shmem_vm_ops = {
+ .fault = drm_gem_shmem_fault,
+ .open = drm_gem_vm_open,
+ .close = drm_gem_shmem_vm_close,
+};
+EXPORT_SYMBOL_GPL(drm_gem_shmem_vm_ops);
I just saw a warning from drm_gem_shmem_put_pages() for
!shmem->pages_use_count -- I think drm_gem_vm_open() needs to
drm_gem_shmem_get_pages().
Yeah we need a drm_gem_shmem_vm_open here.
Adding one of those fixed my refcounting issues, so I've sent out a v6
with it.
Just realized that I've reviewed this patch already, spotted that vma
management issue there too. Plus a pile of other things. From reading that
other thread discussion with Noralf concluded with "not yet ready for
prime time" unfortunately :-/
I saw stuff about how it wasn't usable for SPI because SPI does weird
things with DMA mapping. Was there something else?
Looking through that mail it was a bunch of comments to improve the
kerneldoc. Plus a note that buffer sharing/mmap is going to be all
incoherent and horrible (but I guess for vkms we don't care that much).
I'm just kinda vary of generic buffer handling that turns out to not be
actually all that useful. We have lots of deadends and kinda-midlayers in
this area already (but this one here definitely smells plenty better than
lots of older ones).
FWIW, I really want shmem helpers for v3d. The fault handling in
particular has magic I don't understand, and this is not my first fault
handler. :/
If you can use it for a "real" hw driver like v3d, I think it makes a lot
sense to have it as a helper. I believe udl and a future simpledrm can
also make use of it.
I have an idea about a usb driver that I hope to work on somewhere down
the line that will need this kind of code. So my plan was to resurrect
this code when I got there.
I agree that fault handling looks a bit like magic. I looked at all the
drivers that uses shmem buffers to see what they where doing. When Daniel
put me on the right track with the fake offsets, the fault handler ended
up being quite small.
Having a helper like this that can actually be used for real hw drivers
(if it can, that is), increases the chance of getting this -mm stuff
right. And hopefully someone down the line having domain knowledge can
audit this code. It's less likely that this will happen with code tucked
away in a driver, especially the smaller ones.
Initially I hoped that I could make the helper compatible with vgem, so I
could convert vgem to use this helper. That would give the helper a lot
of testing, making it and keeping it solid. However vgem can get pages
one by one in the fault handler if all pages hasn't been fetched. I
didn't see an easy way to handle that together with page use counting.
The main reason for having page counting was to make it easy to bolt on a
shrinker, but I have no experience nor any knowledge about that, so I
don't know if it can be easily done.
Noralf.
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Re: [Intel-gfx] [PATCH v5 4/5] drm: Add library for shmem backed GEM objects
Daniel Vetter writes:
> On Wed, Nov 28, 2018 at 01:52:56PM -0800, Eric Anholt wrote:
>> Daniel Vetter writes:
>>
>> > On Tue, Nov 27, 2018 at 12:38:44PM -0800, Eric Anholt wrote:
>> >> Daniel Vetter writes:
>> >>
>> >> > On Mon, Nov 26, 2018 at 04:36:21PM -0800, Eric Anholt wrote:
>> >> >> Noralf Trønnes writes:
>> >> >> > +static void drm_gem_shmem_vm_close(struct vm_area_struct *vma)
>> >> >> > +{
>> >> >> > +struct drm_gem_object *obj = vma->vm_private_data;
>> >> >> > +struct drm_gem_shmem_object *shmem = to_drm_gem_shmem_obj(obj);
>> >> >> > +
>> >> >> > +drm_gem_shmem_put_pages(shmem);
>> >> >> > +drm_gem_vm_close(vma);
>> >> >> > +}
>> >> >> > +
>> >> >> > +const struct vm_operations_struct drm_gem_shmem_vm_ops = {
>> >> >> > +.fault = drm_gem_shmem_fault,
>> >> >> > +.open = drm_gem_vm_open,
>> >> >> > +.close = drm_gem_shmem_vm_close,
>> >> >> > +};
>> >> >> > +EXPORT_SYMBOL_GPL(drm_gem_shmem_vm_ops);
>> >> >>
>> >> >> I just saw a warning from drm_gem_shmem_put_pages() for
>> >> >> !shmem->pages_use_count -- I think drm_gem_vm_open() needs to
>> >> >> drm_gem_shmem_get_pages().
>> >> >
>> >> > Yeah we need a drm_gem_shmem_vm_open here.
>> >>
>> >> Adding one of those fixed my refcounting issues, so I've sent out a v6
>> >> with it.
>> >
>> > Just realized that I've reviewed this patch already, spotted that vma
>> > management issue there too. Plus a pile of other things. From reading that
>> > other thread discussion with Noralf concluded with "not yet ready for
>> > prime time" unfortunately :-/
>>
>> I saw stuff about how it wasn't usable for SPI because SPI does weird
>> things with DMA mapping. Was there something else?
>
> Looking through that mail it was a bunch of comments to improve the
> kerneldoc. Plus a note that buffer sharing/mmap is going to be all
> incoherent and horrible (but I guess for vkms we don't care that much).
> I'm just kinda vary of generic buffer handling that turns out to not be
> actually all that useful. We have lots of deadends and kinda-midlayers in
> this area already (but this one here definitely smells plenty better than
> lots of older ones).
FWIW, I really want shmem helpers for v3d. The fault handling in
particular has magic I don't understand, and this is not my first fault
handler. :/
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Re: [Intel-gfx] [PATCH v5 4/5] drm: Add library for shmem backed GEM objects
On Wed, Nov 28, 2018 at 01:52:56PM -0800, Eric Anholt wrote:
> Daniel Vetter writes:
>
> > On Tue, Nov 27, 2018 at 12:38:44PM -0800, Eric Anholt wrote:
> >> Daniel Vetter writes:
> >>
> >> > On Mon, Nov 26, 2018 at 04:36:21PM -0800, Eric Anholt wrote:
> >> >> Noralf Trønnes writes:
> >> >> > +static void drm_gem_shmem_vm_close(struct vm_area_struct *vma)
> >> >> > +{
> >> >> > + struct drm_gem_object *obj = vma->vm_private_data;
> >> >> > + struct drm_gem_shmem_object *shmem = to_drm_gem_shmem_obj(obj);
> >> >> > +
> >> >> > + drm_gem_shmem_put_pages(shmem);
> >> >> > + drm_gem_vm_close(vma);
> >> >> > +}
> >> >> > +
> >> >> > +const struct vm_operations_struct drm_gem_shmem_vm_ops = {
> >> >> > + .fault = drm_gem_shmem_fault,
> >> >> > + .open = drm_gem_vm_open,
> >> >> > + .close = drm_gem_shmem_vm_close,
> >> >> > +};
> >> >> > +EXPORT_SYMBOL_GPL(drm_gem_shmem_vm_ops);
> >> >>
> >> >> I just saw a warning from drm_gem_shmem_put_pages() for
> >> >> !shmem->pages_use_count -- I think drm_gem_vm_open() needs to
> >> >> drm_gem_shmem_get_pages().
> >> >
> >> > Yeah we need a drm_gem_shmem_vm_open here.
> >>
> >> Adding one of those fixed my refcounting issues, so I've sent out a v6
> >> with it.
> >
> > Just realized that I've reviewed this patch already, spotted that vma
> > management issue there too. Plus a pile of other things. From reading that
> > other thread discussion with Noralf concluded with "not yet ready for
> > prime time" unfortunately :-/
>
> I saw stuff about how it wasn't usable for SPI because SPI does weird
> things with DMA mapping. Was there something else?
Looking through that mail it was a bunch of comments to improve the
kerneldoc. Plus a note that buffer sharing/mmap is going to be all
incoherent and horrible (but I guess for vkms we don't care that much).
I'm just kinda vary of generic buffer handling that turns out to not be
actually all that useful. We have lots of deadends and kinda-midlayers in
this area already (but this one here definitely smells plenty better than
lots of older ones).
-Daniel
--
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Software Engineer, Intel Corporation
http://blog.ffwll.ch
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Re: [Intel-gfx] [PATCH v5 4/5] drm: Add library for shmem backed GEM objects
Daniel Vetter writes:
> On Tue, Nov 27, 2018 at 12:38:44PM -0800, Eric Anholt wrote:
>> Daniel Vetter writes:
>>
>> > On Mon, Nov 26, 2018 at 04:36:21PM -0800, Eric Anholt wrote:
>> >> Noralf Trønnes writes:
>> >> > +static void drm_gem_shmem_vm_close(struct vm_area_struct *vma)
>> >> > +{
>> >> > + struct drm_gem_object *obj = vma->vm_private_data;
>> >> > + struct drm_gem_shmem_object *shmem = to_drm_gem_shmem_obj(obj);
>> >> > +
>> >> > + drm_gem_shmem_put_pages(shmem);
>> >> > + drm_gem_vm_close(vma);
>> >> > +}
>> >> > +
>> >> > +const struct vm_operations_struct drm_gem_shmem_vm_ops = {
>> >> > + .fault = drm_gem_shmem_fault,
>> >> > + .open = drm_gem_vm_open,
>> >> > + .close = drm_gem_shmem_vm_close,
>> >> > +};
>> >> > +EXPORT_SYMBOL_GPL(drm_gem_shmem_vm_ops);
>> >>
>> >> I just saw a warning from drm_gem_shmem_put_pages() for
>> >> !shmem->pages_use_count -- I think drm_gem_vm_open() needs to
>> >> drm_gem_shmem_get_pages().
>> >
>> > Yeah we need a drm_gem_shmem_vm_open here.
>>
>> Adding one of those fixed my refcounting issues, so I've sent out a v6
>> with it.
>
> Just realized that I've reviewed this patch already, spotted that vma
> management issue there too. Plus a pile of other things. From reading that
> other thread discussion with Noralf concluded with "not yet ready for
> prime time" unfortunately :-/
I saw stuff about how it wasn't usable for SPI because SPI does weird
things with DMA mapping. Was there something else?
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Re: [Intel-gfx] [PATCH v5 4/5] drm: Add library for shmem backed GEM objects
On Tue, Nov 27, 2018 at 12:38:44PM -0800, Eric Anholt wrote:
> Daniel Vetter writes:
>
> > On Mon, Nov 26, 2018 at 04:36:21PM -0800, Eric Anholt wrote:
> >> Noralf Trønnes writes:
> >> > +static void drm_gem_shmem_vm_close(struct vm_area_struct *vma)
> >> > +{
> >> > +struct drm_gem_object *obj = vma->vm_private_data;
> >> > +struct drm_gem_shmem_object *shmem = to_drm_gem_shmem_obj(obj);
> >> > +
> >> > +drm_gem_shmem_put_pages(shmem);
> >> > +drm_gem_vm_close(vma);
> >> > +}
> >> > +
> >> > +const struct vm_operations_struct drm_gem_shmem_vm_ops = {
> >> > +.fault = drm_gem_shmem_fault,
> >> > +.open = drm_gem_vm_open,
> >> > +.close = drm_gem_shmem_vm_close,
> >> > +};
> >> > +EXPORT_SYMBOL_GPL(drm_gem_shmem_vm_ops);
> >>
> >> I just saw a warning from drm_gem_shmem_put_pages() for
> >> !shmem->pages_use_count -- I think drm_gem_vm_open() needs to
> >> drm_gem_shmem_get_pages().
> >
> > Yeah we need a drm_gem_shmem_vm_open here.
>
> Adding one of those fixed my refcounting issues, so I've sent out a v6
> with it.
Just realized that I've reviewed this patch already, spotted that vma
management issue there too. Plus a pile of other things. From reading that
other thread discussion with Noralf concluded with "not yet ready for
prime time" unfortunately :-/
-Daniel
--
Daniel Vetter
Software Engineer, Intel Corporation
http://blog.ffwll.ch
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Re: [Intel-gfx] [PATCH v5 4/5] drm: Add library for shmem backed GEM objects
Daniel Vetter writes:
> On Mon, Nov 26, 2018 at 04:36:21PM -0800, Eric Anholt wrote:
>> Noralf Trønnes writes:
>> > +static void drm_gem_shmem_vm_close(struct vm_area_struct *vma)
>> > +{
>> > + struct drm_gem_object *obj = vma->vm_private_data;
>> > + struct drm_gem_shmem_object *shmem = to_drm_gem_shmem_obj(obj);
>> > +
>> > + drm_gem_shmem_put_pages(shmem);
>> > + drm_gem_vm_close(vma);
>> > +}
>> > +
>> > +const struct vm_operations_struct drm_gem_shmem_vm_ops = {
>> > + .fault = drm_gem_shmem_fault,
>> > + .open = drm_gem_vm_open,
>> > + .close = drm_gem_shmem_vm_close,
>> > +};
>> > +EXPORT_SYMBOL_GPL(drm_gem_shmem_vm_ops);
>>
>> I just saw a warning from drm_gem_shmem_put_pages() for
>> !shmem->pages_use_count -- I think drm_gem_vm_open() needs to
>> drm_gem_shmem_get_pages().
>
> Yeah we need a drm_gem_shmem_vm_open here.
Adding one of those fixed my refcounting issues, so I've sent out a v6
with it.
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Re: [Intel-gfx] [PATCH v5 4/5] drm: Add library for shmem backed GEM objects
On Mon, Nov 26, 2018 at 04:36:21PM -0800, Eric Anholt wrote:
> Noralf Trønnes writes:
> > +static void drm_gem_shmem_vm_close(struct vm_area_struct *vma)
> > +{
> > + struct drm_gem_object *obj = vma->vm_private_data;
> > + struct drm_gem_shmem_object *shmem = to_drm_gem_shmem_obj(obj);
> > +
> > + drm_gem_shmem_put_pages(shmem);
> > + drm_gem_vm_close(vma);
> > +}
> > +
> > +const struct vm_operations_struct drm_gem_shmem_vm_ops = {
> > + .fault = drm_gem_shmem_fault,
> > + .open = drm_gem_vm_open,
> > + .close = drm_gem_shmem_vm_close,
> > +};
> > +EXPORT_SYMBOL_GPL(drm_gem_shmem_vm_ops);
>
> I just saw a warning from drm_gem_shmem_put_pages() for
> !shmem->pages_use_count -- I think drm_gem_vm_open() needs to
> drm_gem_shmem_get_pages().
Yeah we need a drm_gem_shmem_vm_open here.
-Daniel
--
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Software Engineer, Intel Corporation
http://blog.ffwll.ch
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