Look for amdgpu_ttm_set_active_vram_size(), setting ring->ready to false is directly beneath it.

Christian.

Am 01.03.2018 um 10:41 schrieb Liu, Monk:
Oops, looks only si will call this dma_stop() during hw_fini, I checked for 
sdma4.0/3.0/2.4, no such logic



-----Original Message-----
From: Christian König [mailto:ckoenig.leichtzumer...@gmail.com]
Sent: 2018年3月1日 17:39
To: Liu, Monk <monk....@amd.com>; Koenig, Christian <christian.koe...@amd.com>; 
amd-gfx@lists.freedesktop.org
Subject: Re: [PATCH 3/4] drm/amdgpu: don't return when ring not ready for 
fill_buffer

Hi Monk,

look at si_dma_stop() and/or other SDMA generation code.

Regards,
Christian.

Am 01.03.2018 um 10:37 schrieb Liu, Monk:
Hi Christian

During suspend/resume, which stage will set sdma's ring->ready to
false ?? I can only find it in amdgpu_ring_fini() But I saw that it is
only invoked in unload_kms(), looks device_suspnd() will not set
ring->ready to false

/Monk

-----Original Message-----
From: amd-gfx [mailto:amd-gfx-boun...@lists.freedesktop.org] On Behalf
Of Liu, Monk
Sent: 2018年3月1日 16:52
To: Koenig, Christian <christian.koe...@amd.com>;
amd-gfx@lists.freedesktop.org
Subject: RE: [PATCH 3/4] drm/amdgpu: don't return when ring not ready
for fill_buffer

amdgpu_evict_flags() and amdgpu_bo_move() needs to know if the SDMA ring is 
available during suspend/resume.
As long as we are in gpu reset, we don't return error when ring not ready, cuz 
eventually it either success or failed and rescheduled by scheduler since it is 
kernel job What's your concern ?

/Monk


-----Original Message-----
From: Koenig, Christian
Sent: 2018年3月1日 16:41
To: Liu, Monk <monk....@amd.com>; amd-gfx@lists.freedesktop.org
Subject: Re: [PATCH 3/4] drm/amdgpu: don't return when ring not ready
for fill_buffer

If we are in gpu rest stage, we can let SDMA job live with the case of ring not 
ready,  can you point out where is the problem ?
amdgpu_evict_flags() and amdgpu_bo_move() needs to know if the SDMA ring is 
available during suspend/resume.

E.g. suspend works as this:
1. Evict all normal BOs from VRAM using the SDMA.
2. Disable SDMA, GART, PSP etc... e.g. disable the hardware.
3. Unpin all BOs in VRAM used by hardware engines, e.g. the GART table, 
firmware etc...
4. Evict all remaining BOs from VRAM using CPU copies.

Resume works the other way around:
1. Move all BOs for GART table and firmware back into VRAM using CPU copies.
2. Pin those BOs in VRAM and enable the hardware.
3. Use the SDMA to move back all other BOs into VRAM.

To figure out if we should use the CPU copy or the SDMA the ring->ready flag is 
used. So removing this check is really a no-go because it would break 
suspend/resume.

The only other alternative I can see is to add a separate flag in amdgpu_mman 
if buffer_funcs should be used or not. See all the callers of 
amdgpu_ttm_set_active_vram_size() as well.

Something like renaming amdgpu_ttm_set_active_vram_size() into
amdgpu_ttm_set_buffer_funcs_read() and ignoring any change if gpu_reset is set.

BTW: Changing the active VRAM size in GPU reset is quite a bug you stumbled 
over here, so this really needs fixing anyway.

Regards,
Christian.

Am 01.03.2018 um 09:23 schrieb Liu, Monk:
Accel_working is only for GFX ring, I don't think test it is appropriate for 
SDMA jobs ....

If we are in gpu rest stage, we can let SDMA job live with the case of ring not 
ready,  can you point out where is the problem ?

In fact we did stress TDR test with this patch and it can really fix
couple over kill issues


/Monk

-----Original Message-----
From: Christian König [mailto:ckoenig.leichtzumer...@gmail.com]
Sent: 2018年3月1日 16:16
To: Liu, Monk <monk....@amd.com>; Koenig, Christian
<christian.koe...@amd.com>; amd-gfx@lists.freedesktop.org
Subject: Re: [PATCH 3/4] drm/amdgpu: don't return when ring not ready
for fill_buffer

Ah, crap yeah that won't work since we don't free the ring.

Key point is we need to distinct between the ring doesn't work temporary 
because we are in a GPU reset and it doesn't work at all because we are missing 
firmware or stuff like that.

And no, checking the gpu_reset flag is totally racy and can't be done either. 
How about checking accel_working instead?

Christian.

Am 01.03.2018 um 07:01 schrieb Liu, Monk:
Please change the test to use ring->ring_obj instead, this way we still bail 
out if somebody tries to submit commands before the ring is even allocated.
I don't understand how could fill_buffer() get run under the case that 
ring->ring_obj is not even allocated ... where is such case ?


/Monk

-----Original Message-----
From: Koenig, Christian
Sent: 2018年2月28日 20:46
To: Liu, Monk <monk....@amd.com>; amd-gfx@lists.freedesktop.org
Subject: Re: [PATCH 3/4] drm/amdgpu: don't return when ring not
ready for fill_buffer

Good point, but in this case we need some other handling.

Please change the test to use ring->ring_obj instead, this way we still bail 
out if somebody tries to submit commands before the ring is even allocated.

And you also need to fix a couple of other places in amdgpu_ttm.c.

Regards,
Christian.

Am 28.02.2018 um 13:34 schrieb Liu, Monk:
Because when SDMA was hang by like process A, and meanwhile another
process B is already running into the code of fill_buffer() So just let process 
B continue, don't block it otherwise process B would fail by software reason .

Let it run and finally process B's job would fail and GPU recover
will repeat it again (since it is a kernel job)

Without this solution other process will be greatly harmed by one
black sheep that triggering GPU recover

/Monk



-----Original Message-----
From: Christian König [mailto:ckoenig.leichtzumer...@gmail.com]
Sent: 2018年2月28日 20:24
To: Liu, Monk <monk....@amd.com>; amd-gfx@lists.freedesktop.org
Subject: Re: [PATCH 3/4] drm/amdgpu: don't return when ring not
ready for fill_buffer

Am 28.02.2018 um 08:21 schrieb Monk Liu:
because this time SDMA may under GPU RESET so its ring->ready may
not true, keep going and GPU scheduler will reschedule this job if
it failed.

give a warning on copy_buffer when go through direct_submit while
ring->ready is false
NAK, that test has already saved us quite a bunch of trouble with the fb layer.

Why exactly are you running into issues with that?

Christian.

Change-Id: Ife6cd55e0e843d99900e5bed5418499e88633685
Signed-off-by: Monk Liu <monk....@amd.com>
---
       drivers/gpu/drm/amd/amdgpu/amdgpu_ttm.c | 6 +-----
       1 file changed, 1 insertion(+), 5 deletions(-)

diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_ttm.c
b/drivers/gpu/drm/amd/amdgpu/amdgpu_ttm.c
index e38e6db..7b75ac9 100644
--- a/drivers/gpu/drm/amd/amdgpu/amdgpu_ttm.c
+++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_ttm.c
@@ -1656,6 +1656,7 @@ int amdgpu_copy_buffer(struct amdgpu_ring *ring, uint64_t 
src_offset,
        amdgpu_ring_pad_ib(ring, &job->ibs[0]);
        WARN_ON(job->ibs[0].length_dw > num_dw);
        if (direct_submit) {
+               WARN_ON(!ring->ready);
                r = amdgpu_ib_schedule(ring, job->num_ibs, job->ibs,
                                       NULL, fence);
                job->fence = dma_fence_get(*fence); @@ -1692,11 +1693,6 @@
int amdgpu_fill_buffer(struct amdgpu_bo *bo,
        struct amdgpu_job *job;
        int r;
- if (!ring->ready) {
-               DRM_ERROR("Trying to clear memory with ring turned off.\n");
-               return -EINVAL;
-       }
-
        if (bo->tbo.mem.mem_type == TTM_PL_TT) {
                r = amdgpu_ttm_alloc_gart(&bo->tbo);
                if (r)
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