[PATCH igt 8/9] msm/mapping: Add wait for stall-on-fault to re-arm
Kamil Konieczny
kamil.konieczny at linux.intel.com
Tue Jul 1 16:24:20 UTC 2025
Hi Rob,
On 2025-06-30 at 11:09:02 -0700, Rob Clark wrote:
> From: Rob Clark <rob.clark at oss.qualcomm.com>
>
> Newer kernels disable stall-on-fault for a grace period, to avoid a
> flood of faults causing instability with memory translations that
> the hw attempts with the translation stalled. Fortunately it adds a
Is it system-wide or only for msm driver?
Please improve subject:
[PATCH igt 8/9] tests/msm/msm_mapping: Add wait for stall-on-fault to re-arm
imho it could be shorter:
[PATCH igt 8/9] tests/msm/msm_mapping: Wait for stall-on-fault
Regards,
Kamil
> debugfs file so we can know how long we need to wait for stall-on-
> fault to be re-enabled.
>
> Signed-off-by: Rob Clark <rob.clark at oss.qualcomm.com>
> ---
> tests/msm/msm_mapping.c | 29 +++++++++++++++++++++++++++++
> 1 file changed, 29 insertions(+)
>
> diff --git a/tests/msm/msm_mapping.c b/tests/msm/msm_mapping.c
> index 978ea18375dd..7e2f5c7eadc8 100644
> --- a/tests/msm/msm_mapping.c
> +++ b/tests/msm/msm_mapping.c
> @@ -74,6 +74,30 @@ get_and_clear_devcore(int timeout_ms)
> return buf;
> }
>
> +static void
> +wait_for_stall_on_fault(int drm_fd)
> +{
> + char buf[64] = "\0";
> +
> + do {
> + int us;
> +
> + igt_debugfs_read(drm_fd, "stall_reenable_time_us", buf);
> + if (!strlen(buf)) {
> + /* Not supported on older kernels: */
> + return;
> + }
> +
> + us = atoi(buf);
> + if (!us) {
> + /* Done waiting: */
> + return;
> + }
> +
> + usleep(us);
> + } while (true);
> +}
> +
> /*
> * Helper to find named buffer address
> */
> @@ -224,6 +248,11 @@ do_mapping_test(struct msm_pipe *pipe, const char *buffername, bool write)
> ret = sscanf(s, " - iova=%"PRIx64, &fault_addr);
> igt_fail_on(ret != 1);
> igt_fail_on(addr != fault_addr);
> +
> + /* Wait for stall-on-fault to re-enable, otherwise the next sub-test
> + * would not generate a devcore:
> + */
> + wait_for_stall_on_fault(pipe->dev->fd);
> }
>
> /*
> --
> 2.50.0
>
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