What is handle? What is point?
Handle is a syncobj handle, point is the point in a syncobj timeline. I'll document those fields.
OK.
Why is there padding instead of putting point first?
We can move the point field first, but we need to keep the explicit padding: the struct has to be 64bit aligned because of the __u64 field (which the compiler takes care of) but if we don't have an explicit padding, the unused 32bits are undefined, which might cause trouble if we extend the struct at some point, since we sort of expect that old userspace keep this unused 32bit slot to 0, while new users set non-zero values if they have to.
Makes sense. Reordering still probably makes sense.
> #define PANFROST_BO_REF_EXCLUSIVE 0x1 > +#define PANFROST_BO_REF_NO_IMPLICIT_DEP 0x2This seems logically backwards. NO_IMPLICIT_DEP makes sense if we're trying to keep backwards compatibility, but here you're crafting a new interface totally from scratch. If anything, isn't BO_REF_IMPLICIT_DEP the flag you'd want?
AFAICT, all other drivers make the no-implicit-dep an opt-in, and I didn't want to do things differently in panfrost. But if that's really an issue, I can make it an opt-out.
I don't have strong feelings either way. I was just under the impressions other drivers did this for b/w compat reasons which don't apply here.
Hmm. I'm not /opposed/ and I know kbase uses strides but it seems like somewhat unwarranted complexity, and there is a combinatoric explosion here (if jobs, bo refs, and syncobj refs use 3 different versions, as this encoding permits... as opposed to just specifying a UABI version or something like that)
Sounds like a good idea. I'll add a version field and map that to a <job_stride,bo_ref_stride,syncobj_ref_stride> tuple.
Cc Steven, does this make sense?
- /**
* If the submission fails, this encodes the index of the job* failed.*/- __u32 fail_idx;
What if multiple jobs fail?We stop at the first failure. Note that it's not an execution failure, but a submission failure (AKA, userspace passed wrong params, like invalid BO or synobj handles).
I see, ok.