Re: [igt-dev] [PATCH i-g-t 1/3] i915/gem_eio: Race kms on/off vs reset

Ville Syrjälä
2019-09-19T14:28:20Z

On Wed, Sep 11, 2019 at 11:14:59AM +0100, Chris Wilson wrote:
> On older platforms, performing a GPU reset clobbers the display.
> Exercise the interactions between reset/wedge and the display and
> hopefully prevent any races creeping in.
>
> Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
> Cc: Ville Syrjälä <ville.syrjala@linux.intel.com>
> ---
> tests/i915/gem_eio.c | 79 ++++++++++++++++++++++++++++++++++++++++++++
> 1 file changed, 79 insertions(+)
>
> diff --git a/tests/i915/gem_eio.c b/tests/i915/gem_eio.c
> index 9b086a039..e0213c76c 100644
> --- a/tests/i915/gem_eio.c
> +++ b/tests/i915/gem_eio.c
> @@ -42,6 +42,8 @@
>
> #include "igt.h"
> #include "igt_device.h"
> +#include "igt_fb.h"
> +#include "igt_kms.h"
> #include "igt_stats.h"
> #include "igt_sysfs.h"
> #include "sw_sync.h"
> @@ -813,6 +815,67 @@ static void test_reset_stress(int fd, unsigned int flags)
> gem_context_destroy(fd, ctx0);
> }
>
> +/*
> + * Modesetting vs wedged
> + */
> +
> +static void display_helper(igt_display_t *dpy, int *done)
> +{
> + const int commit = dpy->is_atomic ? COMMIT_ATOMIC : COMMIT_LEGACY;
> + struct igt_fb fb = {};
> +
> + while (!READ_ONCE(*done)) {
> + drmModeModeInfoPtr mode;
> + igt_plane_t *primary;
> + igt_output_t *output;
> + int pipe;
> +
> + pipe = rand() % dpy->n_pipes;

I guess this ends up doing nothing if we get the same pipe twice in a
row? Hmm, I guess it does actually do something but since nothing
significant would change the kernel likely just downgrades it to a
fastset. But maybe that's fine.

There are some reset vs. modeset type of tests in kms_flip, but those
are rather more carefully sequenced so they are probably not so great
at finding new races.

Reviewed-by: Ville Syrjälä <ville.syrjala@linux.intel.com>

> + output = igt_get_single_output_for_pipe(dpy, pipe);
> + if (!output)
> + continue;
> +
> + igt_output_set_pipe(output, pipe);
> + mode = igt_output_get_mode(output);
> +
> + if (fb.width != mode->hdisplay || fb.height != mode->vdisplay) {
> + igt_remove_fb(dpy->drm_fd, &fb);
> + igt_create_pattern_fb(dpy->drm_fd,
> + mode->hdisplay, mode->vdisplay,
> + DRM_FORMAT_XRGB8888,
> + LOCAL_I915_FORMAT_MOD_X_TILED,
> + &fb);
> + }
> +
> + primary = igt_output_get_plane_type(output,
> + DRM_PLANE_TYPE_PRIMARY);
> + igt_plane_set_fb(primary, &fb);
> +
> + igt_display_commit2(dpy, commit);
> + igt_display_reset(dpy);
> + }
> +
> + igt_remove_fb(dpy->drm_fd, &fb);
> +}
> +
> +static void test_kms(int i915, igt_display_t *dpy)
> +{
> + int *shared;
> +
> + shared = mmap(NULL, 4096, PROT_WRITE, MAP_SHARED | MAP_ANON, -1, 0);
> + igt_assert(shared != MAP_FAILED);
> +
> + igt_fork(child, 1)
> + display_helper(dpy, shared);
> +
> + test_reset_stress(i915, 0);
> + test_reset_stress(i915, TEST_WEDGE);
> +
> + *shared = 1;
> + igt_waitchildren();
> + munmap(shared, 4096);
> +}
> +
> static int fd = -1;
>
> static void
> @@ -906,4 +969,20 @@ igt_main
> }
> }
> }
> +
> + igt_subtest_group {
> + igt_display_t display = {
> + .drm_fd = -1, .n_pipes = IGT_MAX_PIPES
> + };
> +
> + igt_fixture {
> + igt_device_set_master(fd);
> +
> + igt_display_require(&display, fd);
> + igt_display_require_output(&display);
> + }
> +
> + igt_subtest("kms")
> + test_kms(fd, &display);
> + }
> }
> --
> 2.23.0

--
Ville Syrjälä
Intel