Hey,
On 01-09-14 18:21, Christian König wrote:
> Am 01.09.2014 um 15:33 schrieb Maarten Lankhorst:
>> Hey,
>>
>> Op 01-09-14 om 14:31 schreef Christian König:
>>> Please wait a second with that.
>>>
>>> I didn't had a chance to test this yet and nobody has yet given it's rb on at least the radeon changes in this branch.
>> Ok, my fault. I thought it was implicitly acked. I haven't made any functional changes to these patches,
>> just some small fixups and a fix to make it apply after the upstream removal of RADEON_FENCE_SIGNALED_SEQ.
>
> Yeah, but the resulting patch looks to complex for my taste and should be simplified a bit more. Here is a more detailed review:
>
>> + wait_queue_t fence_wake;
> Only a nitpick, but please fix the indention and maybe add a comment.
>
>> + struct work_struct delayed_irq_work;
> Just drop that, the new fall back work item should take care of this when the unfortunate case happens that somebody tries to enable_signaling in the middle of a GPU reset.
I can only drop it if radeon_gpu_reset will always call radeon_irq_set after downgrading to read mode, even if no work needs to be done. :-)
Then again, should be possible.
>> /*
>> - * Cast helper
>> - */
>> -#define to_radeon_fence(p) ((struct radeon_fence *)(p))
>> -
>> -/*
> Please define the new cast helper in radeon.h as well.
The ops are only defined in radeon_fence.c, and nothing outside of radeon_fence.c should care about the internals.
>> if (!rdev->needs_reset) {
>> - up_write(&rdev->exclusive_lock);
>> + downgrade_write(&rdev->exclusive_lock);
>> + wake_up_all(&rdev->fence_queue);
>> + up_read(&rdev->exclusive_lock);
>> return 0;
>> }
> Just drop that as well, no need to wake up anybody here.
Maybe not, but if I have to remove delayed_irq_work I do need to add a radeon_irq_set here.
>> downgrade_write(&rdev->exclusive_lock);
>> + wake_up_all(&rdev->fence_queue);
> Same here, the IB test will wake up all fences for recheck anyway.
Same as previous comment. :-)
>> + * radeon_fence_read_seq - Returns the current fence value without updating
>> + *
>> + * @rdev: radeon_device pointer
>> + * @ring: ring index to return the seqno of
>> + */
>> +static uint64_t radeon_fence_read_seq(struct radeon_device *rdev, int ring)
>> +{
>> + uint64_t last_seq = atomic64_read(&rdev->fence_drv[ring].last_seq);
>> + uint64_t last_emitted = rdev->fence_drv[ring].sync_seq[ring];
>> + uint64_t seq = radeon_fence_read(rdev, ring);
>> +
>> + seq = radeon_fence_read(rdev, ring);
>> + seq |= last_seq & 0xffffffff00000000LL;
>> + if (seq < last_seq) {
>> + seq &= 0xffffffff;
>> + seq |= last_emitted & 0xffffffff00000000LL;
>> + }
>> + return seq;
>> +}
> Completely drop that and just check the last_seq signaled as set by radeon_fence_activity.
Do you mean call radeon_fence_activity in radeon_fence_signaled? Or should I just use the cached value in radeon_fence_check_signaled.
I can't call fence_activity in check_signaled, because it would cause re-entrancy in fence_queue.
>> + if (!ret)
>> + FENCE_TRACE(&fence->base, "signaled from irq context\n");
>> + else
>> + FENCE_TRACE(&fence->base, "was already signaled\n");
> Is all that text tracing necessary? Probably better define a trace point here.
It gets optimized out normally. There's already a tracepoint called in fence_signal.
>> + if (atomic64_read(&rdev->fence_drv[fence->ring].last_seq) >= fence->seq ||
>> + !rdev->ddev->irq_enabled)
>> + return false;
> Checking irq_enabled here might not be such a good idea if the fence code don't has a fall back on it's own. What exactly happens if enable_signaling returns false?
I thought irq_enabled couldn't happen under normal circumstances?
Anyway the fence gets treated as signaled if it returns false, and fence_signal will get called.
>> +static signed long radeon_fence_default_wait(struct fence *f, bool intr,
>> + signed long timeout)
>> +{
>> + struct radeon_fence *fence = to_radeon_fence(f);
>> + struct radeon_device *rdev = fence->rdev;
>> + bool signaled;
>> +
>> + fence_enable_sw_signaling(&fence->base);
>> +
>> + /*
>> + * This function has to return -EDEADLK, but cannot hold
>> + * exclusive_lock during the wait because some callers
>> + * may already hold it. This means checking needs_reset without
>> + * lock, and not fiddling with any gpu internals.
>> + *
>> + * The callback installed with fence_enable_sw_signaling will
>> + * run before our wait_event_*timeout call, so we will see
>> + * both the signaled fence and the changes to needs_reset.
>> + */
>> +
>> + if (intr)
>> + timeout = wait_event_interruptible_timeout(rdev->fence_queue,
>> + ((signaled = (test_bit(FENCE_FLAG_SIGNALED_BIT, &fence->base.flags))) || rdev->needs_reset),
>> + timeout);
>> + else
>> + timeout = wait_event_timeout(rdev->fence_queue,
>> + ((signaled = (test_bit(FENCE_FLAG_SIGNALED_BIT, &fence->base.flags))) || rdev->needs_reset),
>> + timeout);
>> +
>> + if (timeout > 0 && !signaled)
>> + return -EDEADLK;
>> + return timeout;
>> +}
> This at least needs to be properly formated, but I think since we now don't need extra handling any more we don't need an extra wait function as well.
I thought of removing the extra handling, but the -EDEADLK stuff is needed because a deadlock could happen in ttm_bo_lock_delayed_workqueue otherwise if the gpu's really hung there would never be any progress forward.
~Maarten
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