Messages in this thread | | | Subject | Re: [PATCHv2 1/4] staging: android: ion: Drop heap type masks | From | Laura Abbott <> | Date | Tue, 6 Sep 2016 15:16:52 -0700 |
| |
On 09/05/2016 04:20 AM, Brian Starkey wrote: > Hi, > > On Fri, Sep 02, 2016 at 12:36:25PM -0700, Laura Abbott wrote: >> On 09/02/2016 06:41 AM, Brian Starkey wrote: >>> Hi Laura, >>> >>> On Thu, Sep 01, 2016 at 03:40:41PM -0700, Laura Abbott wrote: >>>> >>>> There is no advantage to having heap types be a mask. The ion client has >>>> long since dropped the mask. Drop the notion of heap type masks as well. >>>> >>> >>> I know this is the same patch you sent last time, so sorry for not >>> picking this up then - but I'm curious what "The" ion client is here? >>> >> >> ion_client_create used to take a mask to indicate what heap types it >> could allocate from. This hasn't been the case since 2bb9f5034ec7 >> ("gpu: ion: Remove heapmask from client"). "The ion client" probably >> should have been "struct ion_client" > > Ah I see, the in-kernel ion_client. Sorry, I completely forgot that > even existed (because it's totally useless - how is a driver meant to > find the global ion_device?) > >> >>> Our ion client(s) certainly still use these masks, and it's still >>> used as a mask within ion itself - even if the relationship between a >>> mask and a heap type has been somewhat lost. >> >> Where is it used in Ion? I don't see it in tree unless I missed something >> and I'm not eager to keep this around for out of tree code. What's the >> actual use for this? > > You're certainly right that these heap-ID-to-allocation-mask macros > are unused in the kernel, but I don't really see the reason for > removing them - they are convenient (for now). > > Example: I'm using the dummy ion driver, and I want to allocate from > the SYSTEM_CONTIG heap - the ION_HEAP_SYSTEM_CONTIG_MASK gives me the > exact mask I need for that. > > It seems your opinion is that heap-IDs are already, and should be, > completely decoupled from their type. That sounds like a good idea to > me, but it's not true (yet) - again check out the dummy driver. >
Good point, I need to clean up the dummy driver to stop using heap types as the id ;)
I get that it's convenient but it's a bad practice to conflate the namespaces.
> At the moment, heap-IDs are assigned by ion drivers in any way they > see fit. For as long as that stays the case there's always going to > be heap-masks hard-coded in UAPI kernel headers (in-tree or not), so > removing these particular masks seems a bit fruitless. >
It's not fruitless, the concept of type as mask makes no sense. They are two different name spaces and I've found Ion users have a hard time keeping them separate and pass in the heap type mask when using non dummy
> I'd rather see driver-assigned heap-IDs disappear completely, and have > them assigned by ion core from an idr or something. At that point > these macros really *are* meaningless, and I'd be totally fine with > removing them (and userspace won't be able to depend on hard-coded > allocation masks any more - it will have to use the query ioctl, > which I assume is the whole point?). >
Ideally yes we'd be able to get rid of the hard coded device IDs. I consider the query ioctl a stepping stone to that, depending on how enthusiastic people are about Ion.
> IMO it's not the right time to remove these macros, because they still > have meaning and usefulness. >
I still think they should be deleted to avoid namespace polution.
> Cheers, > Brian > >> >>> >>> Thanks, >>> Brian >>> >>>> Signed-off-by: Laura Abbott <labbott@redhat.com> >>>> --- >>>> drivers/staging/android/uapi/ion.h | 6 ------ >>>> 1 file changed, 6 deletions(-) >>>> >>>> diff --git a/drivers/staging/android/uapi/ion.h b/drivers/staging/android/uapi/ion.h >>>> index 0a8e40f..a9c4e8b 100644 >>>> --- a/drivers/staging/android/uapi/ion.h >>>> +++ b/drivers/staging/android/uapi/ion.h >>>> @@ -44,14 +44,8 @@ enum ion_heap_type { >>>> * must be last so device specific heaps always >>>> * are at the end of this enum >>>> */ >>>> - ION_NUM_HEAPS = 16, >>>> }; >>>> >>>> -#define ION_HEAP_SYSTEM_MASK (1 << ION_HEAP_TYPE_SYSTEM) >>>> -#define ION_HEAP_SYSTEM_CONTIG_MASK (1 << ION_HEAP_TYPE_SYSTEM_CONTIG) >>>> -#define ION_HEAP_CARVEOUT_MASK (1 << ION_HEAP_TYPE_CARVEOUT) >>>> -#define ION_HEAP_TYPE_DMA_MASK (1 << ION_HEAP_TYPE_DMA) >>>> - >>>> #define ION_NUM_HEAP_IDS (sizeof(unsigned int) * 8) >>>> >>>> /** >>>> -- >>>> 2.7.4 >>>> >>
| |