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@xxxxxxxxxx>
---
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
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