From b229ea58cbe2f107dc0a7e2c7cdce193f7166b47 Mon Sep 17 00:00:00 2001 From: Maxime Ripard Date: Fri, 28 Jul 2023 11:06:24 +0200 Subject: drm/vc4: tests: pv-muxing: Document test scenario MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit We've had a couple of tests that weren't really obvious, nor did they document what they were supposed to test. Document that to make it hopefully more obvious. Reviewed-by: Javier Martinez Canillas Reviewed-by: Maíra Canal Link: https://lore.kernel.org/r/20230728-kms-kunit-actions-rework-v3-11-952565ccccfe@kernel.org Signed-off-by: Maxime Ripard --- drivers/gpu/drm/vc4/tests/vc4_test_pv_muxing.c | 22 ++++++++++++++++++++++ 1 file changed, 22 insertions(+) (limited to 'drivers/gpu/drm/vc4') diff --git a/drivers/gpu/drm/vc4/tests/vc4_test_pv_muxing.c b/drivers/gpu/drm/vc4/tests/vc4_test_pv_muxing.c index 5f9f5626329d..61622e951031 100644 --- a/drivers/gpu/drm/vc4/tests/vc4_test_pv_muxing.c +++ b/drivers/gpu/drm/vc4/tests/vc4_test_pv_muxing.c @@ -845,6 +845,13 @@ static void drm_test_vc5_pv_muxing_bugs_subsequent_crtc_enable(struct kunit *tes KUNIT_EXPECT_NE(test, hdmi0_channel, hdmi1_channel); } +/* + * This test makes sure that we never change the FIFO of an active HVS + * channel if we disable a FIFO with a lower index. + * + * Doing so would result in a FIFO stall and would disrupt an output + * supposed to be unaffected by the commit. + */ static void drm_test_vc5_pv_muxing_bugs_stable_fifo(struct kunit *test) { struct drm_modeset_acquire_ctx *ctx; @@ -924,6 +931,21 @@ static void drm_test_vc5_pv_muxing_bugs_stable_fifo(struct kunit *test) } } +/* + * Test that if we affect a single output, only the CRTC state of that + * output will be pulled in the global atomic state. + * + * This is relevant for two things: + * + * - If we don't have that state at all, we are unlikely to affect the + * FIFO muxing. This is somewhat redundant with + * drm_test_vc5_pv_muxing_bugs_stable_fifo() + * + * - KMS waits for page flips to occur on all the CRTC found in the + * CRTC state. Since the CRTC is unaffected, we would over-wait, but + * most importantly run into corner cases like waiting on an + * inactive CRTC that never completes. + */ static void drm_test_vc5_pv_muxing_bugs_subsequent_crtc_enable_too_many_crtc_state(struct kunit *test) { -- cgit v1.2.3-58-ga151