2018-07-03 17:07:34

by Eric Anholt

[permalink] [raw]
Subject: [PATCH 1/4] drm/v3d: Delay the scheduler timeout if we're still making progress.

GTF-GLES2.gtf.GL.acos.acos_float_vert_xvary submits jobs that take 4
seconds at maximum resolution, but we still want to reset quickly if a
job is really hung. Sample the CL's current address and the return
address (since we call into tile lists repeatedly) and if either has
changed then assume we've made progress.

Signed-off-by: Eric Anholt <[email protected]>
Cc: Lucas Stach <[email protected]>
---
drivers/gpu/drm/v3d/v3d_drv.h | 2 ++
drivers/gpu/drm/v3d/v3d_regs.h | 1 +
drivers/gpu/drm/v3d/v3d_sched.c | 18 ++++++++++++++++++
3 files changed, 21 insertions(+)

diff --git a/drivers/gpu/drm/v3d/v3d_drv.h b/drivers/gpu/drm/v3d/v3d_drv.h
index f546e0ab9562..a5d96d823416 100644
--- a/drivers/gpu/drm/v3d/v3d_drv.h
+++ b/drivers/gpu/drm/v3d/v3d_drv.h
@@ -189,6 +189,8 @@ struct v3d_job {

/* GPU virtual addresses of the start/end of the CL job. */
u32 start, end;
+
+ u32 timedout_ctca, timedout_ctra;
};

struct v3d_exec_info {
diff --git a/drivers/gpu/drm/v3d/v3d_regs.h b/drivers/gpu/drm/v3d/v3d_regs.h
index fc13282dfc2f..854046565989 100644
--- a/drivers/gpu/drm/v3d/v3d_regs.h
+++ b/drivers/gpu/drm/v3d/v3d_regs.h
@@ -222,6 +222,7 @@
#define V3D_CLE_CTNCA(n) (V3D_CLE_CT0CA + 4 * n)
#define V3D_CLE_CT0RA 0x00118
#define V3D_CLE_CT1RA 0x0011c
+#define V3D_CLE_CTNRA(n) (V3D_CLE_CT0RA + 4 * n)
#define V3D_CLE_CT0LC 0x00120
#define V3D_CLE_CT1LC 0x00124
#define V3D_CLE_CT0PC 0x00128
diff --git a/drivers/gpu/drm/v3d/v3d_sched.c b/drivers/gpu/drm/v3d/v3d_sched.c
index 808bc901f567..00667c733dca 100644
--- a/drivers/gpu/drm/v3d/v3d_sched.c
+++ b/drivers/gpu/drm/v3d/v3d_sched.c
@@ -153,7 +153,25 @@ v3d_job_timedout(struct drm_sched_job *sched_job)
struct v3d_job *job = to_v3d_job(sched_job);
struct v3d_exec_info *exec = job->exec;
struct v3d_dev *v3d = exec->v3d;
+ enum v3d_queue job_q = job == &exec->bin ? V3D_BIN : V3D_RENDER;
enum v3d_queue q;
+ u32 ctca = V3D_CORE_READ(0, V3D_CLE_CTNCA(job_q));
+ u32 ctra = V3D_CORE_READ(0, V3D_CLE_CTNRA(job_q));
+
+ /* If the current address or return address have changed, then
+ * the GPU has probably made progress and we should delay the
+ * reset. This could fail if the GPU got in an infinite loop
+ * in the CL, but that is pretty unlikely outside of an i-g-t
+ * testcase.
+ */
+ if (job->timedout_ctca != ctca || job->timedout_ctra != ctra) {
+ job->timedout_ctca = ctca;
+ job->timedout_ctra = ctra;
+
+ schedule_delayed_work(&job->base.work_tdr,
+ job->base.sched->timeout);
+ return;
+ }

mutex_lock(&v3d->reset_lock);

--
2.18.0



2018-07-03 17:06:54

by Eric Anholt

[permalink] [raw]
Subject: [PATCH 3/4] drm/v3d: Add missing v3d documentation structure.

This was a failure of "git add" on my part -- we already referenced
the doc from drivers.rst.

Signed-off-by: Eric Anholt <[email protected]>
Cc: Daniel Vetter <[email protected]>
---
Documentation/gpu/v3d.rst | 28 ++++++++++++++++++++++++++++
1 file changed, 28 insertions(+)
create mode 100644 Documentation/gpu/v3d.rst

diff --git a/Documentation/gpu/v3d.rst b/Documentation/gpu/v3d.rst
new file mode 100644
index 000000000000..543f7fbf526e
--- /dev/null
+++ b/Documentation/gpu/v3d.rst
@@ -0,0 +1,28 @@
+=====================================
+ drm/v3d Broadcom V3D Graphics Driver
+=====================================
+
+.. kernel-doc:: drivers/gpu/drm/v3d/v3d_drv.c
+ :doc: Broadcom V3D Graphics Driver
+
+GPU buffer object (BO) management
+---------------------------------
+
+.. kernel-doc:: drivers/gpu/drm/v3d/v3d_bo.c
+ :doc: V3D GEM BO management support
+
+Address space management
+===========================================
+.. kernel-doc:: drivers/gpu/drm/v3d/v3d_mmu.c
+ :doc: Broadcom V3D MMU
+
+GPU Scheduling
+===========================================
+.. kernel-doc:: drivers/gpu/drm/v3d/v3d_sched.c
+ :doc: Broadcom V3D scheduling
+
+Interrupts
+--------------
+
+.. kernel-doc:: drivers/gpu/drm/v3d/v3d_irq.c
+ :doc: Interrupt management for the V3D engine
--
2.18.0


2018-07-03 17:08:24

by Eric Anholt

[permalink] [raw]
Subject: [PATCH 4/4] drm/v3d: Fix a grammar nit in the scheduler docs.

Signed-off-by: Eric Anholt <[email protected]>
Cc: Daniel Vetter <[email protected]>
---
drivers/gpu/drm/v3d/v3d_sched.c | 4 ++--
1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/drivers/gpu/drm/v3d/v3d_sched.c b/drivers/gpu/drm/v3d/v3d_sched.c
index 00667c733dca..a5501581d96b 100644
--- a/drivers/gpu/drm/v3d/v3d_sched.c
+++ b/drivers/gpu/drm/v3d/v3d_sched.c
@@ -14,8 +14,8 @@
* to the HW only when it has completed the last one, instead of
* filling up the CT[01]Q FIFOs with jobs. Similarly, we use
* v3d_job_dependency() to manage the dependency between bin and
- * render, instead of having the clients submit jobs with using the
- * HW's semaphores to interlock between them.
+ * render, instead of having the clients submit jobs using the HW's
+ * semaphores to interlock between them.
*/

#include <linux/kthread.h>
--
2.18.0


2018-07-03 17:08:26

by Eric Anholt

[permalink] [raw]
Subject: [PATCH 2/4] drm/v3d: Remove unnecessary dma_fence_ops.

The dma-fence core as of commit 418cc6ca0607 ("dma-fence: Make ->wait
callback optional") provides appropriate defaults for these methods.

Signed-off-by: Eric Anholt <[email protected]>
Cc: Daniel Vetter <[email protected]>
---
drivers/gpu/drm/v3d/v3d_fence.c | 12 ------------
1 file changed, 12 deletions(-)

diff --git a/drivers/gpu/drm/v3d/v3d_fence.c b/drivers/gpu/drm/v3d/v3d_fence.c
index bfe31a89668b..50bfcf9a8a1a 100644
--- a/drivers/gpu/drm/v3d/v3d_fence.c
+++ b/drivers/gpu/drm/v3d/v3d_fence.c
@@ -35,19 +35,7 @@ static const char *v3d_fence_get_timeline_name(struct dma_fence *fence)
return "v3d-render";
}

-static bool v3d_fence_enable_signaling(struct dma_fence *fence)
-{
- return true;
-}
-
const struct dma_fence_ops v3d_fence_ops = {
.get_driver_name = v3d_fence_get_driver_name,
.get_timeline_name = v3d_fence_get_timeline_name,
- .enable_signaling = v3d_fence_enable_signaling,
- /* Each of our fences gets signaled as complete by the IRQ
- * handler, so we rely on the core's tracking of signaling.
- */
- .signaled = NULL,
- .wait = dma_fence_default_wait,
- .release = dma_fence_free,
};
--
2.18.0


2018-07-03 20:46:15

by Alex Deucher

[permalink] [raw]
Subject: Re: [PATCH 1/4] drm/v3d: Delay the scheduler timeout if we're still making progress.

On Tue, Jul 3, 2018 at 1:05 PM, Eric Anholt <[email protected]> wrote:
> GTF-GLES2.gtf.GL.acos.acos_float_vert_xvary submits jobs that take 4
> seconds at maximum resolution, but we still want to reset quickly if a
> job is really hung. Sample the CL's current address and the return
> address (since we call into tile lists repeatedly) and if either has
> changed then assume we've made progress.
>
> Signed-off-by: Eric Anholt <[email protected]>
> Cc: Lucas Stach <[email protected]>

Series is:
Reviewed-by: Alex Deucher <[email protected]>

> ---
> drivers/gpu/drm/v3d/v3d_drv.h | 2 ++
> drivers/gpu/drm/v3d/v3d_regs.h | 1 +
> drivers/gpu/drm/v3d/v3d_sched.c | 18 ++++++++++++++++++
> 3 files changed, 21 insertions(+)
>
> diff --git a/drivers/gpu/drm/v3d/v3d_drv.h b/drivers/gpu/drm/v3d/v3d_drv.h
> index f546e0ab9562..a5d96d823416 100644
> --- a/drivers/gpu/drm/v3d/v3d_drv.h
> +++ b/drivers/gpu/drm/v3d/v3d_drv.h
> @@ -189,6 +189,8 @@ struct v3d_job {
>
> /* GPU virtual addresses of the start/end of the CL job. */
> u32 start, end;
> +
> + u32 timedout_ctca, timedout_ctra;
> };
>
> struct v3d_exec_info {
> diff --git a/drivers/gpu/drm/v3d/v3d_regs.h b/drivers/gpu/drm/v3d/v3d_regs.h
> index fc13282dfc2f..854046565989 100644
> --- a/drivers/gpu/drm/v3d/v3d_regs.h
> +++ b/drivers/gpu/drm/v3d/v3d_regs.h
> @@ -222,6 +222,7 @@
> #define V3D_CLE_CTNCA(n) (V3D_CLE_CT0CA + 4 * n)
> #define V3D_CLE_CT0RA 0x00118
> #define V3D_CLE_CT1RA 0x0011c
> +#define V3D_CLE_CTNRA(n) (V3D_CLE_CT0RA + 4 * n)
> #define V3D_CLE_CT0LC 0x00120
> #define V3D_CLE_CT1LC 0x00124
> #define V3D_CLE_CT0PC 0x00128
> diff --git a/drivers/gpu/drm/v3d/v3d_sched.c b/drivers/gpu/drm/v3d/v3d_sched.c
> index 808bc901f567..00667c733dca 100644
> --- a/drivers/gpu/drm/v3d/v3d_sched.c
> +++ b/drivers/gpu/drm/v3d/v3d_sched.c
> @@ -153,7 +153,25 @@ v3d_job_timedout(struct drm_sched_job *sched_job)
> struct v3d_job *job = to_v3d_job(sched_job);
> struct v3d_exec_info *exec = job->exec;
> struct v3d_dev *v3d = exec->v3d;
> + enum v3d_queue job_q = job == &exec->bin ? V3D_BIN : V3D_RENDER;
> enum v3d_queue q;
> + u32 ctca = V3D_CORE_READ(0, V3D_CLE_CTNCA(job_q));
> + u32 ctra = V3D_CORE_READ(0, V3D_CLE_CTNRA(job_q));
> +
> + /* If the current address or return address have changed, then
> + * the GPU has probably made progress and we should delay the
> + * reset. This could fail if the GPU got in an infinite loop
> + * in the CL, but that is pretty unlikely outside of an i-g-t
> + * testcase.
> + */
> + if (job->timedout_ctca != ctca || job->timedout_ctra != ctra) {
> + job->timedout_ctca = ctca;
> + job->timedout_ctra = ctra;
> +
> + schedule_delayed_work(&job->base.work_tdr,
> + job->base.sched->timeout);
> + return;
> + }
>
> mutex_lock(&v3d->reset_lock);
>
> --
> 2.18.0
>
> _______________________________________________
> dri-devel mailing list
> [email protected]
> https://lists.freedesktop.org/mailman/listinfo/dri-devel

2018-07-04 08:33:16

by Daniel Vetter

[permalink] [raw]
Subject: Re: [PATCH 1/4] drm/v3d: Delay the scheduler timeout if we're still making progress.

On Tue, Jul 03, 2018 at 10:05:12AM -0700, Eric Anholt wrote:
> GTF-GLES2.gtf.GL.acos.acos_float_vert_xvary submits jobs that take 4
> seconds at maximum resolution, but we still want to reset quickly if a
> job is really hung. Sample the CL's current address and the return
> address (since we call into tile lists repeatedly) and if either has
> changed then assume we've made progress.
>
> Signed-off-by: Eric Anholt <[email protected]>
> Cc: Lucas Stach <[email protected]>
> ---
> drivers/gpu/drm/v3d/v3d_drv.h | 2 ++
> drivers/gpu/drm/v3d/v3d_regs.h | 1 +
> drivers/gpu/drm/v3d/v3d_sched.c | 18 ++++++++++++++++++
> 3 files changed, 21 insertions(+)
>
> diff --git a/drivers/gpu/drm/v3d/v3d_drv.h b/drivers/gpu/drm/v3d/v3d_drv.h
> index f546e0ab9562..a5d96d823416 100644
> --- a/drivers/gpu/drm/v3d/v3d_drv.h
> +++ b/drivers/gpu/drm/v3d/v3d_drv.h
> @@ -189,6 +189,8 @@ struct v3d_job {
>
> /* GPU virtual addresses of the start/end of the CL job. */
> u32 start, end;
> +
> + u32 timedout_ctca, timedout_ctra;
> };
>
> struct v3d_exec_info {
> diff --git a/drivers/gpu/drm/v3d/v3d_regs.h b/drivers/gpu/drm/v3d/v3d_regs.h
> index fc13282dfc2f..854046565989 100644
> --- a/drivers/gpu/drm/v3d/v3d_regs.h
> +++ b/drivers/gpu/drm/v3d/v3d_regs.h
> @@ -222,6 +222,7 @@
> #define V3D_CLE_CTNCA(n) (V3D_CLE_CT0CA + 4 * n)
> #define V3D_CLE_CT0RA 0x00118
> #define V3D_CLE_CT1RA 0x0011c
> +#define V3D_CLE_CTNRA(n) (V3D_CLE_CT0RA + 4 * n)
> #define V3D_CLE_CT0LC 0x00120
> #define V3D_CLE_CT1LC 0x00124
> #define V3D_CLE_CT0PC 0x00128
> diff --git a/drivers/gpu/drm/v3d/v3d_sched.c b/drivers/gpu/drm/v3d/v3d_sched.c
> index 808bc901f567..00667c733dca 100644
> --- a/drivers/gpu/drm/v3d/v3d_sched.c
> +++ b/drivers/gpu/drm/v3d/v3d_sched.c
> @@ -153,7 +153,25 @@ v3d_job_timedout(struct drm_sched_job *sched_job)
> struct v3d_job *job = to_v3d_job(sched_job);
> struct v3d_exec_info *exec = job->exec;
> struct v3d_dev *v3d = exec->v3d;
> + enum v3d_queue job_q = job == &exec->bin ? V3D_BIN : V3D_RENDER;
> enum v3d_queue q;
> + u32 ctca = V3D_CORE_READ(0, V3D_CLE_CTNCA(job_q));
> + u32 ctra = V3D_CORE_READ(0, V3D_CLE_CTNRA(job_q));
> +
> + /* If the current address or return address have changed, then
> + * the GPU has probably made progress and we should delay the
> + * reset. This could fail if the GPU got in an infinite loop
> + * in the CL, but that is pretty unlikely outside of an i-g-t
> + * testcase.
> + */

In i915 we have a credit system that allows only a limited amount of
postponing the timeout. That would block the fairly easy DOS. Otoh I have
no idea how robust v3d is against DOS attacks at the ioctl level and
whether that's worth it.

From your description I'm assuming that a loop in the shaders won't trick
this, so ARB_robustness/WebGL should still be happy.

Anyway, Ack on the entire pile.
-Daniel
> + if (job->timedout_ctca != ctca || job->timedout_ctra != ctra) {
> + job->timedout_ctca = ctca;
> + job->timedout_ctra = ctra;
> +
> + schedule_delayed_work(&job->base.work_tdr,
> + job->base.sched->timeout);
> + return;
> + }
>
> mutex_lock(&v3d->reset_lock);
>
> --
> 2.18.0
>
> _______________________________________________
> dri-devel mailing list
> [email protected]
> https://lists.freedesktop.org/mailman/listinfo/dri-devel

--
Daniel Vetter
Software Engineer, Intel Corporation
http://blog.ffwll.ch

2018-07-05 11:01:07

by Lucas Stach

[permalink] [raw]
Subject: Re: [PATCH 1/4] drm/v3d: Delay the scheduler timeout if we're still making progress.

Am Dienstag, den 03.07.2018, 10:05 -0700 schrieb Eric Anholt:
> GTF-GLES2.gtf.GL.acos.acos_float_vert_xvary submits jobs that take 4
> seconds at maximum resolution, but we still want to reset quickly if a
> job is really hung.  Sample the CL's current address and the return
> address (since we call into tile lists repeatedly) and if either has
> changed then assume we've made progress.

So this means you are doubling your timeout? AFAICS for the first time
you hit the timeout handler the cached ctca and ctra values will
probably always differ from the current values. Maybe this warrants a
mention in the commit message, as it's changing the behavior of the
scheduler timeout.

Also how easy is it for userspace to construct such an infinite loop in
the CL? Thinking about a rogue client DoSing the GPU while exploiting
this check in the timeout handler to stay under the radar...

Regards,
Lucas

> Signed-off-by: Eric Anholt <[email protected]>
> > Cc: Lucas Stach <[email protected]>
> ---
>  drivers/gpu/drm/v3d/v3d_drv.h   |  2 ++
>  drivers/gpu/drm/v3d/v3d_regs.h  |  1 +
>  drivers/gpu/drm/v3d/v3d_sched.c | 18 ++++++++++++++++++
>  3 files changed, 21 insertions(+)
>
> diff --git a/drivers/gpu/drm/v3d/v3d_drv.h b/drivers/gpu/drm/v3d/v3d_drv.h
> index f546e0ab9562..a5d96d823416 100644
> --- a/drivers/gpu/drm/v3d/v3d_drv.h
> +++ b/drivers/gpu/drm/v3d/v3d_drv.h
> @@ -189,6 +189,8 @@ struct v3d_job {
>  
> >   /* GPU virtual addresses of the start/end of the CL job. */
> >   u32 start, end;
> +
> > + u32 timedout_ctca, timedout_ctra;
>  };
>  
>  struct v3d_exec_info {
> diff --git a/drivers/gpu/drm/v3d/v3d_regs.h b/drivers/gpu/drm/v3d/v3d_regs.h
> index fc13282dfc2f..854046565989 100644
> --- a/drivers/gpu/drm/v3d/v3d_regs.h
> +++ b/drivers/gpu/drm/v3d/v3d_regs.h
> @@ -222,6 +222,7 @@
>  #define V3D_CLE_CTNCA(n) (V3D_CLE_CT0CA + 4 * n)
>  #define V3D_CLE_CT0RA                                  0x00118
>  #define V3D_CLE_CT1RA                                  0x0011c
> +#define V3D_CLE_CTNRA(n) (V3D_CLE_CT0RA + 4 * n)
>  #define V3D_CLE_CT0LC                                  0x00120
>  #define V3D_CLE_CT1LC                                  0x00124
>  #define V3D_CLE_CT0PC                                  0x00128
> diff --git a/drivers/gpu/drm/v3d/v3d_sched.c b/drivers/gpu/drm/v3d/v3d_sched.c
> index 808bc901f567..00667c733dca 100644
> --- a/drivers/gpu/drm/v3d/v3d_sched.c
> +++ b/drivers/gpu/drm/v3d/v3d_sched.c
> @@ -153,7 +153,25 @@ v3d_job_timedout(struct drm_sched_job *sched_job)
> >   struct v3d_job *job = to_v3d_job(sched_job);
> >   struct v3d_exec_info *exec = job->exec;
> >   struct v3d_dev *v3d = exec->v3d;
> > + enum v3d_queue job_q = job == &exec->bin ? V3D_BIN : V3D_RENDER;
> >   enum v3d_queue q;
> > + u32 ctca = V3D_CORE_READ(0, V3D_CLE_CTNCA(job_q));
> > + u32 ctra = V3D_CORE_READ(0, V3D_CLE_CTNRA(job_q));
> +
> > + /* If the current address or return address have changed, then
> > +  * the GPU has probably made progress and we should delay the
> > +  * reset.  This could fail if the GPU got in an infinite loop
> > +  * in the CL, but that is pretty unlikely outside of an i-g-t
> > +  * testcase.
> > +  */
> > + if (job->timedout_ctca != ctca || job->timedout_ctra != ctra) {
> > + job->timedout_ctca = ctca;
> > + job->timedout_ctra = ctra;
> +
> > + schedule_delayed_work(&job->base.work_tdr,
> > +       job->base.sched->timeout);
> > + return;
> > + }
>  
> >   mutex_lock(&v3d->reset_lock);
>  

2018-07-05 17:01:58

by Eric Anholt

[permalink] [raw]
Subject: Re: [PATCH 1/4] drm/v3d: Delay the scheduler timeout if we're still making progress.

Lucas Stach <[email protected]> writes:

> Am Dienstag, den 03.07.2018, 10:05 -0700 schrieb Eric Anholt:
>> GTF-GLES2.gtf.GL.acos.acos_float_vert_xvary submits jobs that take 4
>> seconds at maximum resolution, but we still want to reset quickly if a
>> job is really hung.  Sample the CL's current address and the return
>> address (since we call into tile lists repeatedly) and if either has
>> changed then assume we've made progress.
>
> So this means you are doubling your timeout? AFAICS for the first time
> you hit the timeout handler the cached ctca and ctra values will
> probably always differ from the current values. Maybe this warrants a
> mention in the commit message, as it's changing the behavior of the
> scheduler timeout.

I supposes that doubles the minimum timeout, but I don't think there's
any principled choice behind that value.

> Also how easy is it for userspace to construct such an infinite loop in
> the CL? Thinking about a rogue client DoSing the GPU while exploiting
> this check in the timeout handler to stay under the radar...

You'd need to have a big enough CL that you don't sample the same
location twice in a row, but otherwise it's trivial and equivalent to a
V3D33 igt case I wrote. I don't think we as the kernel particularly
cares to protect from that case, though -- it's mainly "does a broken
WebGL shader take down your desktop?" which we will still be protecting
from. If you wanted to protect from a general userspace attacker, you
could have a maximum 1 minute timeout or something, but I'm not sure
your life is actually much better when you let an arbitrary number of
clients submit many jobs to round-robin through each of which has a long
timeout like that.


Attachments:
signature.asc (847.00 B)

2018-07-06 10:07:29

by Lucas Stach

[permalink] [raw]
Subject: Re: [PATCH 1/4] drm/v3d: Delay the scheduler timeout if we're still making progress.

Am Dienstag, den 03.07.2018, 10:05 -0700 schrieb Eric Anholt:
> GTF-GLES2.gtf.GL.acos.acos_float_vert_xvary submits jobs that take 4
> seconds at maximum resolution, but we still want to reset quickly if a
> job is really hung.  Sample the CL's current address and the return
> address (since we call into tile lists repeatedly) and if either has
> changed then assume we've made progress.
>
> > Signed-off-by: Eric Anholt <[email protected]>
> Cc: Lucas Stach <[email protected]>

Reviewed-by: Lucas Stach <[email protected]>

> ---
>  drivers/gpu/drm/v3d/v3d_drv.h   |  2 ++
>  drivers/gpu/drm/v3d/v3d_regs.h  |  1 +
>  drivers/gpu/drm/v3d/v3d_sched.c | 18 ++++++++++++++++++
>  3 files changed, 21 insertions(+)
>
> diff --git a/drivers/gpu/drm/v3d/v3d_drv.h b/drivers/gpu/drm/v3d/v3d_drv.h
> index f546e0ab9562..a5d96d823416 100644
> --- a/drivers/gpu/drm/v3d/v3d_drv.h
> +++ b/drivers/gpu/drm/v3d/v3d_drv.h
> @@ -189,6 +189,8 @@ struct v3d_job {
>  
> >   /* GPU virtual addresses of the start/end of the CL job. */
> >   u32 start, end;
> +
> > + u32 timedout_ctca, timedout_ctra;
>  };
>  
>  struct v3d_exec_info {
> diff --git a/drivers/gpu/drm/v3d/v3d_regs.h b/drivers/gpu/drm/v3d/v3d_regs.h
> index fc13282dfc2f..854046565989 100644
> --- a/drivers/gpu/drm/v3d/v3d_regs.h
> +++ b/drivers/gpu/drm/v3d/v3d_regs.h
> @@ -222,6 +222,7 @@
>  #define V3D_CLE_CTNCA(n) (V3D_CLE_CT0CA + 4 * n)
>  #define V3D_CLE_CT0RA                                  0x00118
>  #define V3D_CLE_CT1RA                                  0x0011c
> +#define V3D_CLE_CTNRA(n) (V3D_CLE_CT0RA + 4 * n)
>  #define V3D_CLE_CT0LC                                  0x00120
>  #define V3D_CLE_CT1LC                                  0x00124
>  #define V3D_CLE_CT0PC                                  0x00128
> diff --git a/drivers/gpu/drm/v3d/v3d_sched.c b/drivers/gpu/drm/v3d/v3d_sched.c
> index 808bc901f567..00667c733dca 100644
> --- a/drivers/gpu/drm/v3d/v3d_sched.c
> +++ b/drivers/gpu/drm/v3d/v3d_sched.c
> @@ -153,7 +153,25 @@ v3d_job_timedout(struct drm_sched_job *sched_job)
> >   struct v3d_job *job = to_v3d_job(sched_job);
> >   struct v3d_exec_info *exec = job->exec;
> >   struct v3d_dev *v3d = exec->v3d;
> > + enum v3d_queue job_q = job == &exec->bin ? V3D_BIN : V3D_RENDER;
> >   enum v3d_queue q;
> > + u32 ctca = V3D_CORE_READ(0, V3D_CLE_CTNCA(job_q));
> > + u32 ctra = V3D_CORE_READ(0, V3D_CLE_CTNRA(job_q));
> +
> > + /* If the current address or return address have changed, then
> > +  * the GPU has probably made progress and we should delay the
> > +  * reset.  This could fail if the GPU got in an infinite loop
> > +  * in the CL, but that is pretty unlikely outside of an i-g-t
> > +  * testcase.
> > +  */
> > + if (job->timedout_ctca != ctca || job->timedout_ctra != ctra) {
> > + job->timedout_ctca = ctca;
> > + job->timedout_ctra = ctra;
> +
> > + schedule_delayed_work(&job->base.work_tdr,
> > +       job->base.sched->timeout);
> > + return;
> > + }
>  
> >   mutex_lock(&v3d->reset_lock);
>