| Message ID | 1444164433-9107-2-git-send-email-labbott@fedoraproject.org (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
On Tue, Oct 6, 2015 at 3:47 PM, Laura Abbott <labbott@fedoraproject.org> wrote: > From: Laura Abbott <laura@labbott.name> > > > This adds a base set of devicetree bindings for the Ion memory > manager. This supports setting up the generic set of heaps and > their properties. > > Signed-off-by: Laura Abbott <laura@labbott.name> > Signed-off-by: Andrew Andrianov <andrew@ncrmnt.org> > --- > drivers/staging/android/ion/devicetree.txt | 53 ++++++++++++++++++++++++++++++ I have no issue with this going in here, but I do have lots of issues with this binding. > 1 file changed, 53 insertions(+) > create mode 100644 drivers/staging/android/ion/devicetree.txt > > diff --git a/drivers/staging/android/ion/devicetree.txt b/drivers/staging/android/ion/devicetree.txt > new file mode 100644 > index 0000000..4a0c941 > --- /dev/null > +++ b/drivers/staging/android/ion/devicetree.txt > @@ -0,0 +1,53 @@ > +Ion Memory Manager > + > +Ion is a memory manager that allows for sharing of buffers via dma-buf. > +Ion allows for different types of allocation via an abstraction called > +a 'heap'. A heap represents a specific type of memory. Each heap has > +a different type. There can be multiple instances of the same heap > +type. > + > +Required properties for Ion > + > +- compatible: "linux,ion" > + > +All child nodes of a linux,ion node are interpreted as heaps > + > +required properties for heaps > + > +- linux,ion-heap-id: The Ion heap id used for allocation selection > +- linux,ion-heap-type: Ion heap type defined in ion.h > +- linux,ion-heap-name: Human readble name of the heap > + > + > +Optional properties > +- memory-region: A phandle to a memory region. Required for DMA heap type > +(see reserved-memory.txt for details on the reservation) > +- linux,ion-heap-align: Alignment for the heap. > + > +Example: > + > + ion { > + compatbile = "linux,ion"; > + #address-cells = <1>; > + #size-cells = <0>; > + > + ion-system-heap { > + linux,ion-heap-id = <0>; > + linux,ion-heap-type = <ION_SYSTEM_HEAP_TYPE>; > + linux,ion-heap-name = "system"; How does this vary across platforms? Is all of this being pushed down to DT, because there is no coordination of this at the kernel ABI level across platforms. In other words, why can't heap 0 be hardcoded as system heap in the driver. It seems to me any 1 of these 3 properties could be used to derive the other 2. > + }; > + > + ion-camera-region { > + linux,ion-heap-id = <1>; > + linux,ion-heap-type = <ION_DMA_HEAP_TYPE>; > + linux,ion-heap-name = "camera" > + memory-region = <&camera_region>; Couldn't the memory-region node with addition properties or some standardization of existing ones provide enough information for ION's needs? > + }; > + > + ion-fb-region { > + linux,ion-heap-id = <2>; > + linux,ion-heap-type = <ION_DMA_HEAP_TYPE>; > + linux,ion-heap-name = "fb" > + memory-region = <&fb_region>; > + }; > + } > -- > 2.4.3 >
On 10/6/15 3:35 PM, Rob Herring wrote: > On Tue, Oct 6, 2015 at 3:47 PM, Laura Abbott <labbott@fedoraproject.org> wrote: >> From: Laura Abbott <laura@labbott.name> >> >> >> This adds a base set of devicetree bindings for the Ion memory >> manager. This supports setting up the generic set of heaps and >> their properties. >> >> Signed-off-by: Laura Abbott <laura@labbott.name> >> Signed-off-by: Andrew Andrianov <andrew@ncrmnt.org> >> --- >> drivers/staging/android/ion/devicetree.txt | 53 ++++++++++++++++++++++++++++++ > > I have no issue with this going in here, but I do have lots of issues > with this binding. > >> 1 file changed, 53 insertions(+) >> create mode 100644 drivers/staging/android/ion/devicetree.txt >> >> diff --git a/drivers/staging/android/ion/devicetree.txt b/drivers/staging/android/ion/devicetree.txt >> new file mode 100644 >> index 0000000..4a0c941 >> --- /dev/null >> +++ b/drivers/staging/android/ion/devicetree.txt >> @@ -0,0 +1,53 @@ >> +Ion Memory Manager >> + >> +Ion is a memory manager that allows for sharing of buffers via dma-buf. >> +Ion allows for different types of allocation via an abstraction called >> +a 'heap'. A heap represents a specific type of memory. Each heap has >> +a different type. There can be multiple instances of the same heap >> +type. >> + >> +Required properties for Ion >> + >> +- compatible: "linux,ion" >> + >> +All child nodes of a linux,ion node are interpreted as heaps >> + >> +required properties for heaps >> + >> +- linux,ion-heap-id: The Ion heap id used for allocation selection >> +- linux,ion-heap-type: Ion heap type defined in ion.h >> +- linux,ion-heap-name: Human readble name of the heap >> + >> + >> +Optional properties >> +- memory-region: A phandle to a memory region. Required for DMA heap type >> +(see reserved-memory.txt for details on the reservation) >> +- linux,ion-heap-align: Alignment for the heap. >> + >> +Example: >> + >> + ion { >> + compatbile = "linux,ion"; >> + #address-cells = <1>; >> + #size-cells = <0>; >> + >> + ion-system-heap { >> + linux,ion-heap-id = <0>; >> + linux,ion-heap-type = <ION_SYSTEM_HEAP_TYPE>; >> + linux,ion-heap-name = "system"; > > How does this vary across platforms? Is all of this being pushed down > to DT, because there is no coordination of this at the kernel ABI > level across platforms. In other words, why can't heap 0 be hardcoded > as system heap in the driver. It seems to me any 1 of these 3 > properties could be used to derive the other 2. > Right now there is no guarantee heap IDs will be the same across platforms. The heap IDs are currently part of the userspace ABI as well since userspace clients must pass in a mask of the heap IDs to allocate from. If we assume all existing clients could change, heaps such as the system heap could be mandated to have the same heap ID but we'd still run into problems if you have multiple heaps of the same type (e.g. multiple carveouts) An alternative might be to have each heap just be a compatible string and pull everything (id, type etc.) into C files for setup. I debated doing that but decided to try putting everything in DT for my first pass. > >> + }; >> + >> + ion-camera-region { >> + linux,ion-heap-id = <1>; >> + linux,ion-heap-type = <ION_DMA_HEAP_TYPE>; >> + linux,ion-heap-name = "camera" >> + memory-region = <&camera_region>; > > Couldn't the memory-region node with addition properties or some > standardization of existing ones provide enough information for ION's > needs? > I think we could probably derive most of it from the memory-region right now. If it's reusable, it's DMA, if not it goes to a carveout. Name can come from the node name. heap ID and whether or not a region is a chunk heap could be added as properties. We'd still need to be able to get the same information for heaps that don't correspond to a specific region like the system heap. >> + }; >> + >> + ion-fb-region { >> + linux,ion-heap-id = <2>; >> + linux,ion-heap-type = <ION_DMA_HEAP_TYPE>; >> + linux,ion-heap-name = "fb" >> + memory-region = <&fb_region>; >> + }; >> + } >> -- >> 2.4.3 >>
On 2015-10-07 02:01, Laura Abbott wrote: > On 10/6/15 3:35 PM, Rob Herring wrote: >> On Tue, Oct 6, 2015 at 3:47 PM, Laura Abbott >> <labbott@fedoraproject.org> wrote: >>> From: Laura Abbott <laura@labbott.name> >>> >>> >>> This adds a base set of devicetree bindings for the Ion memory >>> manager. This supports setting up the generic set of heaps and >>> their properties. >>> >>> Signed-off-by: Laura Abbott <laura@labbott.name> >>> Signed-off-by: Andrew Andrianov <andrew@ncrmnt.org> >>> --- >>> drivers/staging/android/ion/devicetree.txt | 53 >>> ++++++++++++++++++++++++++++++ >> >> I have no issue with this going in here, but I do have lots of issues >> with this binding. >> >>> 1 file changed, 53 insertions(+) >>> create mode 100644 drivers/staging/android/ion/devicetree.txt >>> >>> diff --git a/drivers/staging/android/ion/devicetree.txt >>> b/drivers/staging/android/ion/devicetree.txt >>> new file mode 100644 >>> index 0000000..4a0c941 >>> --- /dev/null >>> +++ b/drivers/staging/android/ion/devicetree.txt >>> @@ -0,0 +1,53 @@ >>> +Ion Memory Manager >>> + >>> +Ion is a memory manager that allows for sharing of buffers via >>> dma-buf. >>> +Ion allows for different types of allocation via an abstraction >>> called >>> +a 'heap'. A heap represents a specific type of memory. Each heap has >>> +a different type. There can be multiple instances of the same heap >>> +type. >>> + >>> +Required properties for Ion >>> + >>> +- compatible: "linux,ion" >>> + >>> +All child nodes of a linux,ion node are interpreted as heaps >>> + >>> +required properties for heaps >>> + >>> +- linux,ion-heap-id: The Ion heap id used for allocation selection >>> +- linux,ion-heap-type: Ion heap type defined in ion.h >>> +- linux,ion-heap-name: Human readble name of the heap >>> + >>> + >>> +Optional properties >>> +- memory-region: A phandle to a memory region. Required for DMA heap >>> type >>> +(see reserved-memory.txt for details on the reservation) >>> +- linux,ion-heap-align: Alignment for the heap. >>> + >>> +Example: >>> + >>> + ion { >>> + compatbile = "linux,ion"; >>> + #address-cells = <1>; >>> + #size-cells = <0>; >>> + >>> + ion-system-heap { >>> + linux,ion-heap-id = <0>; >>> + linux,ion-heap-type = <ION_SYSTEM_HEAP_TYPE>; >>> + linux,ion-heap-name = "system"; >> >> How does this vary across platforms? Is all of this being pushed down >> to DT, because there is no coordination of this at the kernel ABI >> level across platforms. In other words, why can't heap 0 be hardcoded >> as system heap in the driver. It seems to me any 1 of these 3 >> properties could be used to derive the other 2. >> > > Right now there is no guarantee heap IDs will be the same across > platforms. The heap IDs are currently part of the userspace ABI > as well since userspace clients must pass in a mask of the heap > IDs to allocate from. If we assume all existing clients could change, > heaps such as the system heap could be mandated to have the same > heap ID but we'd still run into problems if you have multiple > heaps of the same type (e.g. multiple carveouts) I don't really like the idea of enforcing any IDs here. As of now heap ids are generally something VERY platform-specific (or even product-specific). Personally I'd prefer something like this for userspace apps: int id1 = ion_get_heap_id("camera"); if (id1 < 0) { fprintf(stderr, "Invalid heap id"); exit(1); } int id2 = ion_get_heap_id("backup-heap"); if (id2 < 0) { fprintf(stderr, "Invalid heap id"); exit(1); } ... int ret = ion_alloc(fd, 0x100, 0x4, (id1 | id2), 0, &handle); What concerns kernel stuff, things are simpler - we may just pass the heap to use by a reference in devicetree node for that driver. Something like that: ... ion-decoder-region : region_ddr { linux,ion-heap-id = <1>; linux,ion-heap-type = <ION_DMA_HEAP_TYPE>; linux,ion-heap-name = "decoder_mem" memory-region = <&camera_region>; }; ... video_decoder@80180000 { compatible = "acme,h266dec"; reg = <0x80180000 0x20000>, reg-names = "registers"; interrupts = <12>; interrupt-parent = <&vic1>; ion-heaps-for-buffers = <&ion-decoder-region> }; > > An alternative might be to have each heap just be a compatible string > and pull everything (id, type etc.) into C files for setup. I debated > doing that but decided to try putting everything in DT for my first > pass. > >> >>> + }; >>> + >>> + ion-camera-region { >>> + linux,ion-heap-id = <1>; >>> + linux,ion-heap-type = <ION_DMA_HEAP_TYPE>; >>> + linux,ion-heap-name = "camera" >>> + memory-region = <&camera_region>; >> >> Couldn't the memory-region node with addition properties or some >> standardization of existing ones provide enough information for ION's >> needs? >> > > I think we could probably derive most of it from the memory-region > right > now. If it's reusable, it's DMA, if not it goes to a carveout. Name can > come from the node name. heap ID and whether or not a region is a chunk > heap could be added as properties. > > We'd still need to be able to get the same information for heaps that > don't correspond to a specific region like the system heap. > >>> + }; >>> + >>> + ion-fb-region { >>> + linux,ion-heap-id = <2>; >>> + linux,ion-heap-type = <ION_DMA_HEAP_TYPE>; >>> + linux,ion-heap-name = "fb" >>> + memory-region = <&fb_region>; >>> + }; >>> + } >>> -- >>> 2.4.3 >>>
On Wed, Oct 7, 2015 at 5:36 AM, Andrew <andrew@ncrmnt.org> wrote: > On 2015-10-07 02:01, Laura Abbott wrote: >> >> On 10/6/15 3:35 PM, Rob Herring wrote: >>> >>> On Tue, Oct 6, 2015 at 3:47 PM, Laura Abbott <labbott@fedoraproject.org> >>> wrote: >>>> >>>> From: Laura Abbott <laura@labbott.name> >>>> >>>> >>>> This adds a base set of devicetree bindings for the Ion memory >>>> manager. This supports setting up the generic set of heaps and >>>> their properties. >>>> >>>> Signed-off-by: Laura Abbott <laura@labbott.name> >>>> Signed-off-by: Andrew Andrianov <andrew@ncrmnt.org> >>>> --- >>>> drivers/staging/android/ion/devicetree.txt | 53 >>>> ++++++++++++++++++++++++++++++ >>> >>> >>> I have no issue with this going in here, but I do have lots of issues >>> with this binding. >>> >>>> 1 file changed, 53 insertions(+) >>>> create mode 100644 drivers/staging/android/ion/devicetree.txt >>>> >>>> diff --git a/drivers/staging/android/ion/devicetree.txt >>>> b/drivers/staging/android/ion/devicetree.txt >>>> new file mode 100644 >>>> index 0000000..4a0c941 >>>> --- /dev/null >>>> +++ b/drivers/staging/android/ion/devicetree.txt >>>> @@ -0,0 +1,53 @@ >>>> +Ion Memory Manager >>>> + >>>> +Ion is a memory manager that allows for sharing of buffers via dma-buf. >>>> +Ion allows for different types of allocation via an abstraction called >>>> +a 'heap'. A heap represents a specific type of memory. Each heap has >>>> +a different type. There can be multiple instances of the same heap >>>> +type. >>>> + >>>> +Required properties for Ion >>>> + >>>> +- compatible: "linux,ion" >>>> + >>>> +All child nodes of a linux,ion node are interpreted as heaps >>>> + >>>> +required properties for heaps >>>> + >>>> +- linux,ion-heap-id: The Ion heap id used for allocation selection >>>> +- linux,ion-heap-type: Ion heap type defined in ion.h >>>> +- linux,ion-heap-name: Human readble name of the heap >>>> + >>>> + >>>> +Optional properties >>>> +- memory-region: A phandle to a memory region. Required for DMA heap >>>> type >>>> +(see reserved-memory.txt for details on the reservation) >>>> +- linux,ion-heap-align: Alignment for the heap. >>>> + >>>> +Example: >>>> + >>>> + ion { >>>> + compatbile = "linux,ion"; >>>> + #address-cells = <1>; >>>> + #size-cells = <0>; >>>> + >>>> + ion-system-heap { >>>> + linux,ion-heap-id = <0>; >>>> + linux,ion-heap-type = <ION_SYSTEM_HEAP_TYPE>; >>>> + linux,ion-heap-name = "system"; >>> >>> >>> How does this vary across platforms? Is all of this being pushed down >>> to DT, because there is no coordination of this at the kernel ABI >>> level across platforms. In other words, why can't heap 0 be hardcoded >>> as system heap in the driver. It seems to me any 1 of these 3 >>> properties could be used to derive the other 2. >>> >> >> Right now there is no guarantee heap IDs will be the same across >> platforms. The heap IDs are currently part of the userspace ABI >> as well since userspace clients must pass in a mask of the heap >> IDs to allocate from. If we assume all existing clients could change, >> heaps such as the system heap could be mandated to have the same >> heap ID but we'd still run into problems if you have multiple >> heaps of the same type (e.g. multiple carveouts) Vendors largely ignore the kernel-userspace ABI and anything in staging is not a ABI. So arguments about what the ABI is currently is pointless IMO. Pushing an inconsistent kernel ABI to DT is not the answer. > > I don't really like the idea of enforcing any IDs here. As of now > heap ids are generally something VERY platform-specific > (or even product-specific). Personally I'd prefer something like this > for userspace apps: > > int id1 = ion_get_heap_id("camera"); > if (id1 < 0) { > fprintf(stderr, "Invalid heap id"); > exit(1); > } > > int id2 = ion_get_heap_id("backup-heap"); > if (id2 < 0) { > fprintf(stderr, "Invalid heap id"); > exit(1); > } We've learned that creating number spaces like this are bad (irqs, gpios, /dev nodes). We should move away from that. Why should userspace care about IDs or what the IDs are? An ID is just encoding certain implicit requirements. So are the strings here. Users should express what capabilities, restrictions, etc. they have, and then the kernel can find the best heap. > ... > > int ret = ion_alloc(fd, 0x100, 0x4, > (id1 | id2), > 0, &handle); > > > What concerns kernel stuff, things are simpler - we may just pass the heap > to use > by a reference in devicetree node for that driver. Something like that: > > ... > ion-decoder-region : region_ddr { > linux,ion-heap-id = <1>; > linux,ion-heap-type = <ION_DMA_HEAP_TYPE>; > linux,ion-heap-name = "decoder_mem" > memory-region = <&camera_region>; > }; > ... > video_decoder@80180000 { > compatible = "acme,h266dec"; > reg = <0x80180000 0x20000>, > reg-names = "registers"; > interrupts = <12>; > interrupt-parent = <&vic1>; > ion-heaps-for-buffers = <&ion-decoder-region> This is how memory-region is supposed to work. I don't see why we need an additional level of indirection. Rob
On 2015-10-07 21:36, Rob Herring wrote: > On Wed, Oct 7, 2015 at 5:36 AM, Andrew <andrew@ncrmnt.org> wrote: >> On 2015-10-07 02:01, Laura Abbott wrote: >>> >>> On 10/6/15 3:35 PM, Rob Herring wrote: >>>> >>>> On Tue, Oct 6, 2015 at 3:47 PM, Laura Abbott >>>> <labbott@fedoraproject.org> >>>> wrote: >>>>> >>>>> From: Laura Abbott <laura@labbott.name> >>>>> >>>>> >>>>> This adds a base set of devicetree bindings for the Ion memory >>>>> manager. This supports setting up the generic set of heaps and >>>>> their properties. >>>>> >>>>> Signed-off-by: Laura Abbott <laura@labbott.name> >>>>> Signed-off-by: Andrew Andrianov <andrew@ncrmnt.org> >>>>> --- >>>>> drivers/staging/android/ion/devicetree.txt | 53 >>>>> ++++++++++++++++++++++++++++++ >>>> >>>> >>>> I have no issue with this going in here, but I do have lots of >>>> issues >>>> with this binding. >>>> >>>>> 1 file changed, 53 insertions(+) >>>>> create mode 100644 drivers/staging/android/ion/devicetree.txt >>>>> >>>>> diff --git a/drivers/staging/android/ion/devicetree.txt >>>>> b/drivers/staging/android/ion/devicetree.txt >>>>> new file mode 100644 >>>>> index 0000000..4a0c941 >>>>> --- /dev/null >>>>> +++ b/drivers/staging/android/ion/devicetree.txt >>>>> @@ -0,0 +1,53 @@ >>>>> +Ion Memory Manager >>>>> + >>>>> +Ion is a memory manager that allows for sharing of buffers via >>>>> dma-buf. >>>>> +Ion allows for different types of allocation via an abstraction >>>>> called >>>>> +a 'heap'. A heap represents a specific type of memory. Each heap >>>>> has >>>>> +a different type. There can be multiple instances of the same heap >>>>> +type. >>>>> + >>>>> +Required properties for Ion >>>>> + >>>>> +- compatible: "linux,ion" >>>>> + >>>>> +All child nodes of a linux,ion node are interpreted as heaps >>>>> + >>>>> +required properties for heaps >>>>> + >>>>> +- linux,ion-heap-id: The Ion heap id used for allocation selection >>>>> +- linux,ion-heap-type: Ion heap type defined in ion.h >>>>> +- linux,ion-heap-name: Human readble name of the heap >>>>> + >>>>> + >>>>> +Optional properties >>>>> +- memory-region: A phandle to a memory region. Required for DMA >>>>> heap >>>>> type >>>>> +(see reserved-memory.txt for details on the reservation) >>>>> +- linux,ion-heap-align: Alignment for the heap. >>>>> + >>>>> +Example: >>>>> + >>>>> + ion { >>>>> + compatbile = "linux,ion"; >>>>> + #address-cells = <1>; >>>>> + #size-cells = <0>; >>>>> + >>>>> + ion-system-heap { >>>>> + linux,ion-heap-id = <0>; >>>>> + linux,ion-heap-type = >>>>> <ION_SYSTEM_HEAP_TYPE>; >>>>> + linux,ion-heap-name = "system"; >>>> >>>> >>>> How does this vary across platforms? Is all of this being pushed >>>> down >>>> to DT, because there is no coordination of this at the kernel ABI >>>> level across platforms. In other words, why can't heap 0 be >>>> hardcoded >>>> as system heap in the driver. It seems to me any 1 of these 3 >>>> properties could be used to derive the other 2. >>>> >>> >>> Right now there is no guarantee heap IDs will be the same across >>> platforms. The heap IDs are currently part of the userspace ABI >>> as well since userspace clients must pass in a mask of the heap >>> IDs to allocate from. If we assume all existing clients could change, >>> heaps such as the system heap could be mandated to have the same >>> heap ID but we'd still run into problems if you have multiple >>> heaps of the same type (e.g. multiple carveouts) > > Vendors largely ignore the kernel-userspace ABI and anything in > staging is not a ABI. So arguments about what the ABI is currently is > pointless IMO. > > Pushing an inconsistent kernel ABI to DT is not the answer. Totally agree here. > >> >> I don't really like the idea of enforcing any IDs here. As of now >> heap ids are generally something VERY platform-specific >> (or even product-specific). Personally I'd prefer something like this >> for userspace apps: >> >> int id1 = ion_get_heap_id("camera"); >> if (id1 < 0) { >> fprintf(stderr, "Invalid heap id"); >> exit(1); >> } >> >> int id2 = ion_get_heap_id("backup-heap"); >> if (id2 < 0) { >> fprintf(stderr, "Invalid heap id"); >> exit(1); >> } > > We've learned that creating number spaces like this are bad (irqs, > gpios, /dev nodes). We should move away from that. Why should > userspace care about IDs or what the IDs are? An ID is just encoding > certain implicit requirements. So are the strings here. Users should > express what capabilities, restrictions, etc. they have, and then the > kernel can find the best heap. I'd argue about that point, since sometimes kernel might NOT know all the hardware details behind some of the heaps or how they are going to be used. Hence it can't decide a proper heap. And that's where things get ugly. Real-world example: There are several on-chip SRAM banks that make up several heaps. Say, IM0, IM1, IM2. Technically - they are all DMA, and all work. But the hardware guys hand you a handful of weird recommendations, like: * Decoder will work faster if you use bank IM2 for internal buffers, and prefer DDR bank A for decoded frames. * DSP should stick with IM1, and please prefer DDR bank B for buffers When several such devices are involved in one chain - things may get even weirder. Having manual control over where allocations are made allows us to keep all these voodoo magicks away from the kernel and (hopefully) keep vendors from dirty hacks into ion itself. > >> ... >> >> int ret = ion_alloc(fd, 0x100, 0x4, >> (id1 | id2), >> 0, &handle); >> >> >> What concerns kernel stuff, things are simpler - we may just pass the >> heap >> to use >> by a reference in devicetree node for that driver. Something like >> that: >> >> ... >> ion-decoder-region : region_ddr { >> linux,ion-heap-id = <1>; >> linux,ion-heap-type = <ION_DMA_HEAP_TYPE>; >> linux,ion-heap-name = "decoder_mem" >> memory-region = <&camera_region>; >> }; >> ... >> video_decoder@80180000 { >> compatible = "acme,h266dec"; >> reg = <0x80180000 0x20000>, >> reg-names = "registers"; >> interrupts = <12>; >> interrupt-parent = <&vic1>; >> ion-heaps-for-buffers = <&ion-decoder-region> > > This is how memory-region is supposed to work. I don't see why we need > an additional level of indirection. I don't see right now a clean way of getting ion heap id from driver when having a memory-region referenced there. Correct me if if I'm all wrong about it. > > Rob
On 10/7/15 11:36 AM, Rob Herring wrote: > On Wed, Oct 7, 2015 at 5:36 AM, Andrew <andrew@ncrmnt.org> wrote: >> On 2015-10-07 02:01, Laura Abbott wrote: >>> >>> On 10/6/15 3:35 PM, Rob Herring wrote: >>>> >>>> On Tue, Oct 6, 2015 at 3:47 PM, Laura Abbott <labbott@fedoraproject.org> >>>> wrote: >>>>> >>>>> From: Laura Abbott <laura@labbott.name> >>>>> >>>>> >>>>> This adds a base set of devicetree bindings for the Ion memory >>>>> manager. This supports setting up the generic set of heaps and >>>>> their properties. >>>>> >>>>> Signed-off-by: Laura Abbott <laura@labbott.name> >>>>> Signed-off-by: Andrew Andrianov <andrew@ncrmnt.org> >>>>> --- >>>>> drivers/staging/android/ion/devicetree.txt | 53 >>>>> ++++++++++++++++++++++++++++++ >>>> >>>> >>>> I have no issue with this going in here, but I do have lots of issues >>>> with this binding. >>>> >>>>> 1 file changed, 53 insertions(+) >>>>> create mode 100644 drivers/staging/android/ion/devicetree.txt >>>>> >>>>> diff --git a/drivers/staging/android/ion/devicetree.txt >>>>> b/drivers/staging/android/ion/devicetree.txt >>>>> new file mode 100644 >>>>> index 0000000..4a0c941 >>>>> --- /dev/null >>>>> +++ b/drivers/staging/android/ion/devicetree.txt >>>>> @@ -0,0 +1,53 @@ >>>>> +Ion Memory Manager >>>>> + >>>>> +Ion is a memory manager that allows for sharing of buffers via dma-buf. >>>>> +Ion allows for different types of allocation via an abstraction called >>>>> +a 'heap'. A heap represents a specific type of memory. Each heap has >>>>> +a different type. There can be multiple instances of the same heap >>>>> +type. >>>>> + >>>>> +Required properties for Ion >>>>> + >>>>> +- compatible: "linux,ion" >>>>> + >>>>> +All child nodes of a linux,ion node are interpreted as heaps >>>>> + >>>>> +required properties for heaps >>>>> + >>>>> +- linux,ion-heap-id: The Ion heap id used for allocation selection >>>>> +- linux,ion-heap-type: Ion heap type defined in ion.h >>>>> +- linux,ion-heap-name: Human readble name of the heap >>>>> + >>>>> + >>>>> +Optional properties >>>>> +- memory-region: A phandle to a memory region. Required for DMA heap >>>>> type >>>>> +(see reserved-memory.txt for details on the reservation) >>>>> +- linux,ion-heap-align: Alignment for the heap. >>>>> + >>>>> +Example: >>>>> + >>>>> + ion { >>>>> + compatbile = "linux,ion"; >>>>> + #address-cells = <1>; >>>>> + #size-cells = <0>; >>>>> + >>>>> + ion-system-heap { >>>>> + linux,ion-heap-id = <0>; >>>>> + linux,ion-heap-type = <ION_SYSTEM_HEAP_TYPE>; >>>>> + linux,ion-heap-name = "system"; >>>> >>>> >>>> How does this vary across platforms? Is all of this being pushed down >>>> to DT, because there is no coordination of this at the kernel ABI >>>> level across platforms. In other words, why can't heap 0 be hardcoded >>>> as system heap in the driver. It seems to me any 1 of these 3 >>>> properties could be used to derive the other 2. >>>> >>> >>> Right now there is no guarantee heap IDs will be the same across >>> platforms. The heap IDs are currently part of the userspace ABI >>> as well since userspace clients must pass in a mask of the heap >>> IDs to allocate from. If we assume all existing clients could change, >>> heaps such as the system heap could be mandated to have the same >>> heap ID but we'd still run into problems if you have multiple >>> heaps of the same type (e.g. multiple carveouts) > > Vendors largely ignore the kernel-userspace ABI and anything in > staging is not a ABI. So arguments about what the ABI is currently is > pointless IMO. > > Pushing an inconsistent kernel ABI to DT is not the answer. > I'm not sure I agree it's inconsistent because it varies across platforms. IRQs vary across platforms (yes I know something something hardware description). Vendors really should be caring about ABIs and it's kind of a chicken and egg problem about when staging driver ABIs should be considered stable. Perhaps it should be "Pushing bad kernel ABIs to DT is not the answer" which is a fair objection to Ion. >> >> I don't really like the idea of enforcing any IDs here. As of now >> heap ids are generally something VERY platform-specific >> (or even product-specific). Personally I'd prefer something like this >> for userspace apps: >> >> int id1 = ion_get_heap_id("camera"); >> if (id1 < 0) { >> fprintf(stderr, "Invalid heap id"); >> exit(1); >> } >> >> int id2 = ion_get_heap_id("backup-heap"); >> if (id2 < 0) { >> fprintf(stderr, "Invalid heap id"); >> exit(1); >> } > > We've learned that creating number spaces like this are bad (irqs, > gpios, /dev nodes). We should move away from that. Why should > userspace care about IDs or what the IDs are? An ID is just encoding > certain implicit requirements. So are the strings here. Users should > express what capabilities, restrictions, etc. they have, and then the > kernel can find the best heap. > I'd argue that the heap IDs are expressing capabilities and restrictions. A heap ID for camera could be contiguous on one system and discontiguous on another based on the system. The user only gives the ID, not the type so it's ultimately up to the kernel to decide what that heap ID means on a particular system. Ion allows or'ing of heap IDs together and the kernel selects them currently based on priority. What's your idea for expressing the capabilities without resorting IDs? I'm going to give some more thought to this but I think I might look into just having each heap be a compatible string. This might fit in better with something that belongs in devicetree: each heap is describing a platform capability (discontiguous memory, CMA, carved out, releases bees etc.). Anything outside of a compatible string can probably be pulled back into the kernel. Thanks, Laura
On Tue, Oct 06 2015 at 05:35:41 PM, Rob Herring <robherring2@gmail.com> wrote: > On Tue, Oct 6, 2015 at 3:47 PM, Laura Abbott <labbott@fedoraproject.org> wrote: [...] >> +Example: >> + >> + ion { >> + compatbile = "linux,ion"; >> + #address-cells = <1>; >> + #size-cells = <0>; >> + >> + ion-system-heap { >> + linux,ion-heap-id = <0>; >> + linux,ion-heap-type = <ION_SYSTEM_HEAP_TYPE>; >> + linux,ion-heap-name = "system"; > > How does this vary across platforms? Is all of this being pushed down > to DT, because there is no coordination of this at the kernel ABI > level across platforms. In other words, why can't heap 0 be hardcoded > as system heap in the driver. It seems to me any 1 of these 3 > properties could be used to derive the other 2. The heap-id<->heap-type mapping isn't necessarily 1:1. As Laura indicated elsewhere on this thread, a given heap might need to be contiguous on one platform but not on another. In that case you just swap out the heap-type here and there's no need for userspace to change. The heap-name, OTOH, could be derived from the heap-id, which is what we hackishly do here [1] and here[2]. [1] https://www.codeaurora.org/cgit/quic/la/kernel/msm-3.14/tree/drivers/staging/android/ion/msm/msm_ion.c?h=msm-3.14#n53 [2] https://www.codeaurora.org/cgit/quic/la/kernel/msm-3.14/tree/drivers/staging/android/ion/msm/msm_ion.c?h=msm-3.14#n398 -Mitch
On 2015-10-12 21:39, Mitchel Humpherys wrote: > On Tue, Oct 06 2015 at 05:35:41 PM, Rob Herring <robherring2@gmail.com> > wrote: >> On Tue, Oct 6, 2015 at 3:47 PM, Laura Abbott >> <labbott@fedoraproject.org> wrote: > > [...] > >>> +Example: >>> + >>> + ion { >>> + compatbile = "linux,ion"; >>> + #address-cells = <1>; >>> + #size-cells = <0>; >>> + >>> + ion-system-heap { >>> + linux,ion-heap-id = <0>; >>> + linux,ion-heap-type = <ION_SYSTEM_HEAP_TYPE>; >>> + linux,ion-heap-name = "system"; >> >> How does this vary across platforms? Is all of this being pushed down >> to DT, because there is no coordination of this at the kernel ABI >> level across platforms. In other words, why can't heap 0 be hardcoded >> as system heap in the driver. It seems to me any 1 of these 3 >> properties could be used to derive the other 2. > > The heap-id<->heap-type mapping isn't necessarily 1:1. As Laura > indicated elsewhere on this thread, a given heap might need to be > contiguous on one platform but not on another. In that case you just > swap out the heap-type here and there's no need for userspace to > change. > > The heap-name, OTOH, could be derived from the heap-id, which is what > we > hackishly do here [1] and here[2]. By the way, since we agreed that heap id and heap type mappings are not 1:1 - we have a problem with the current API. In userspace we currently have this: int ion_alloc(int fd, size_t len, size_t align, unsigned int heap_mask, unsigned int flags, ion_user_handle_t *handle); We do not specify here what TYPE of heap we want the allocation to come from. This may lead to very unpleasant stuff when porting from one platfrom to another. But, manual heap id control is VERY neat, since it allows to cover a lot of platform-specific cases, where allocating memory from certain heaps can yield performance boost. In other words - maybe we should specify both suitable heap types and heap ids? > [1] > https://www.codeaurora.org/cgit/quic/la/kernel/msm-3.14/tree/drivers/staging/android/ion/msm/msm_ion.c?h=msm-3.14#n53 > [2] > https://www.codeaurora.org/cgit/quic/la/kernel/msm-3.14/tree/drivers/staging/android/ion/msm/msm_ion.c?h=msm-3.14#n398 > > > -Mitch
On Tue, Oct 13 2015 at 11:14:23 AM, Andrew <andrew@ncrmnt.org> wrote: > On 2015-10-12 21:39, Mitchel Humpherys wrote: >> On Tue, Oct 06 2015 at 05:35:41 PM, Rob Herring <robherring2@gmail.com> >> wrote: >>> On Tue, Oct 6, 2015 at 3:47 PM, Laura Abbott <labbott@fedoraproject.org> >>> wrote: >> >> [...] >> >>>> +Example: >>>> + >>>> + ion { >>>> + compatbile = "linux,ion"; >>>> + #address-cells = <1>; >>>> + #size-cells = <0>; >>>> + >>>> + ion-system-heap { >>>> + linux,ion-heap-id = <0>; >>>> + linux,ion-heap-type = <ION_SYSTEM_HEAP_TYPE>; >>>> + linux,ion-heap-name = "system"; >>> >>> How does this vary across platforms? Is all of this being pushed down >>> to DT, because there is no coordination of this at the kernel ABI >>> level across platforms. In other words, why can't heap 0 be hardcoded >>> as system heap in the driver. It seems to me any 1 of these 3 >>> properties could be used to derive the other 2. >> >> The heap-id<->heap-type mapping isn't necessarily 1:1. As Laura >> indicated elsewhere on this thread, a given heap might need to be >> contiguous on one platform but not on another. In that case you just >> swap out the heap-type here and there's no need for userspace to change. >> >> The heap-name, OTOH, could be derived from the heap-id, which is what we >> hackishly do here [1] and here[2]. > > By the way, since we agreed that heap id and heap type mappings > are not 1:1 - we have a problem with the current API. > > In userspace we currently have this: > > int ion_alloc(int fd, size_t len, size_t align, unsigned int heap_mask, > unsigned int flags, ion_user_handle_t *handle); > > We do not specify here what TYPE of heap we want the allocation to come > from. > This may lead to very unpleasant stuff when porting from one platfrom to > another. What "unpleasant stuff" are you referring to, exactly? Abstracting the heap type away from userspace has actually made our lives easier since userspace doesn't need to know anything about the properties of the underlying platform. It just asks for a buffer from the "camera" heap, for example. On some platforms that's contiguous, on others it's not. -Mitch
20 ??????? 2015 ?., 19:34, "Mitchel Humpherys" <mitchelh@codeaurora.org> ???????: > On Tue, Oct 13 2015 at 11:14:23 AM, Andrew <andrew@ncrmnt.org> wrote: > >> On 2015-10-12 21:39, Mitchel Humpherys wrote: >>> On Tue, Oct 06 2015 at 05:35:41 PM, Rob Herring <robherring2@gmail.com> >>> wrote: >>>> On Tue, Oct 6, 2015 at 3:47 PM, Laura Abbott <labbott@fedoraproject.org> >>>> wrote: >>> >>> [...] >>> >>>>> +Example: >>>>> + >>>>> + ion { >>>>> + compatbile = "linux,ion"; >>>>> + #address-cells = <1>; >>>>> + #size-cells = <0>; >>>>> + >>>>> + ion-system-heap { >>>>> + linux,ion-heap-id = <0>; >>>>> + linux,ion-heap-type = <ION_SYSTEM_HEAP_TYPE>; >>>>> + linux,ion-heap-name = "system"; >>>> >>>> How does this vary across platforms? Is all of this being pushed down >>>> to DT, because there is no coordination of this at the kernel ABI >>>> level across platforms. In other words, why can't heap 0 be hardcoded >>>> as system heap in the driver. It seems to me any 1 of these 3 >>>> properties could be used to derive the other 2. >>> >>> The heap-id<->heap-type mapping isn't necessarily 1:1. As Laura >>> indicated elsewhere on this thread, a given heap might need to be >>> contiguous on one platform but not on another. In that case you just >>> swap out the heap-type here and there's no need for userspace to change. >>> >>> The heap-name, OTOH, could be derived from the heap-id, which is what we >>> hackishly do here [1] and here[2]. >> >> By the way, since we agreed that heap id and heap type mappings >> are not 1:1 - we have a problem with the current API. >> >> In userspace we currently have this: >> >> int ion_alloc(int fd, size_t len, size_t align, unsigned int heap_mask, >> unsigned int flags, ion_user_handle_t *handle); >> >> We do not specify here what TYPE of heap we want the allocation to come >> from. >> This may lead to very unpleasant stuff when porting from one platfrom to >> another. Okay, I may be totally missing some point here then. > What "unpleasant stuff" are you referring to, exactly? It's not really clear for me how (and at where - kernel or userspace) we should properly sort out cases when the next device the pipeline introduces some constraints on the buffer it can use. For instance: camera can save data into a non-contiguous buffer, but the image processing hardware (that may or may not be involved) expects the buffer to be contiguous. > Abstracting the > heap type away from userspace has actually made our lives easier since > userspace doesn't need to know anything about the properties of the > underlying platform. It just asks for a buffer from the "camera" heap, > for example. On some platforms that's contiguous, on others it's not. > > -Mitch > > -- > Qualcomm Innovation Center, Inc. > The Qualcomm Innovation Center, Inc. is a member of the Code Aurora Forum, > a Linux Foundation Collaborative Project Regards, Andrew
On 10/22/15 3:36 AM, andrew@ncrmnt.org wrote: > 20 ??????? 2015 ?., 19:34, "Mitchel Humpherys" <mitchelh@codeaurora.org> ???????: >> On Tue, Oct 13 2015 at 11:14:23 AM, Andrew <andrew@ncrmnt.org> wrote: >> >>> On 2015-10-12 21:39, Mitchel Humpherys wrote: >>>> On Tue, Oct 06 2015 at 05:35:41 PM, Rob Herring <robherring2@gmail.com> >>>> wrote: >>>>> On Tue, Oct 6, 2015 at 3:47 PM, Laura Abbott <labbott@fedoraproject.org> >>>>> wrote: >>>> >>>> [...] >>>> >>>>>> +Example: >>>>>> + >>>>>> + ion { >>>>>> + compatbile = "linux,ion"; >>>>>> + #address-cells = <1>; >>>>>> + #size-cells = <0>; >>>>>> + >>>>>> + ion-system-heap { >>>>>> + linux,ion-heap-id = <0>; >>>>>> + linux,ion-heap-type = <ION_SYSTEM_HEAP_TYPE>; >>>>>> + linux,ion-heap-name = "system"; >>>>> >>>>> How does this vary across platforms? Is all of this being pushed down >>>>> to DT, because there is no coordination of this at the kernel ABI >>>>> level across platforms. In other words, why can't heap 0 be hardcoded >>>>> as system heap in the driver. It seems to me any 1 of these 3 >>>>> properties could be used to derive the other 2. >>>> >>>> The heap-id<->heap-type mapping isn't necessarily 1:1. As Laura >>>> indicated elsewhere on this thread, a given heap might need to be >>>> contiguous on one platform but not on another. In that case you just >>>> swap out the heap-type here and there's no need for userspace to change. >>>> >>>> The heap-name, OTOH, could be derived from the heap-id, which is what we >>>> hackishly do here [1] and here[2]. >>> >>> By the way, since we agreed that heap id and heap type mappings >>> are not 1:1 - we have a problem with the current API. >>> >>> In userspace we currently have this: >>> >>> int ion_alloc(int fd, size_t len, size_t align, unsigned int heap_mask, >>> unsigned int flags, ion_user_handle_t *handle); >>> >>> We do not specify here what TYPE of heap we want the allocation to come >>> from. >>> This may lead to very unpleasant stuff when porting from one platfrom to >>> another. > > Okay, I may be totally missing some point here then. > >> What "unpleasant stuff" are you referring to, exactly? > > It's not really clear for me how (and at where - kernel or userspace) > we should properly sort out cases when the next device the pipeline > introduces some constraints on the buffer it can use. > > For instance: camera can save data into a non-contiguous buffer, but the > image processing hardware (that may or may not be involved) expects the > buffer to be contiguous. > You've just hit on one of the open problems. There isn't a good answer right now for how that is supposed to work. Sumit was working on cenalloc as an answer to some of that. I think we've decided that may become more of a long term theoretical problem to solve rather than a pressing practical problem. These days IOMMUs and the like are much more common across the entire system so it's becoming rarer to have a case where some hardware can have discontiguous buffers but some cannot. This isn't to say it's not a problem that needs to be solved, but we're focusing on other efforts of Ion right now. In general though we're working off the assumption that the kernel knows the constraints and if userspace is requesting memory from a particular heap the kernel will allocate the correct memory. This means that it's up to the kernel to set up the heaps correctly for a particular platform (once again, an open problem). Thanks, Laura
diff --git a/drivers/staging/android/ion/devicetree.txt b/drivers/staging/android/ion/devicetree.txt new file mode 100644 index 0000000..4a0c941 --- /dev/null +++ b/drivers/staging/android/ion/devicetree.txt @@ -0,0 +1,53 @@ +Ion Memory Manager + +Ion is a memory manager that allows for sharing of buffers via dma-buf. +Ion allows for different types of allocation via an abstraction called +a 'heap'. A heap represents a specific type of memory. Each heap has +a different type. There can be multiple instances of the same heap +type. + +Required properties for Ion + +- compatible: "linux,ion" + +All child nodes of a linux,ion node are interpreted as heaps + +required properties for heaps + +- linux,ion-heap-id: The Ion heap id used for allocation selection +- linux,ion-heap-type: Ion heap type defined in ion.h +- linux,ion-heap-name: Human readble name of the heap + + +Optional properties +- memory-region: A phandle to a memory region. Required for DMA heap type +(see reserved-memory.txt for details on the reservation) +- linux,ion-heap-align: Alignment for the heap. + +Example: + + ion { + compatbile = "linux,ion"; + #address-cells = <1>; + #size-cells = <0>; + + ion-system-heap { + linux,ion-heap-id = <0>; + linux,ion-heap-type = <ION_SYSTEM_HEAP_TYPE>; + linux,ion-heap-name = "system"; + }; + + ion-camera-region { + linux,ion-heap-id = <1>; + linux,ion-heap-type = <ION_DMA_HEAP_TYPE>; + linux,ion-heap-name = "camera" + memory-region = <&camera_region>; + }; + + ion-fb-region { + linux,ion-heap-id = <2>; + linux,ion-heap-type = <ION_DMA_HEAP_TYPE>; + linux,ion-heap-name = "fb" + memory-region = <&fb_region>; + }; + }