Re: [PATCH 1/2] drm/i915: Unset legacy_cursor_update early in intel_atomic_commit, v3.

Maarten Lankhorst
2017-09-19T13:50:52Z

Op 19-09-17 om 15:38 schreef Ville Syrjälä:
> On Tue, Sep 19, 2017 at 02:14:18PM +0200, Maarten Lankhorst wrote:
>> Commit b44d5c0c105a ("drm/i915: Always wait for flip_done, v2.") removed
>> the call to wait_for_vblanks and replaced it with flip_done.
>>
>> Unfortunately legacy_cursor_update was unset too late, and the
>> replacement call drm_atomic_helper_wait_for_flip_done() was
>> a noop. Make sure that its unset before setup_commit() is
>> called to fix this issue.
>>
>> Changes since v1:
>> - Force vblank wait for watermarks not yet converted to atomic too. (Ville)
>> - Use for_each_new_intel_crtc_in_state. (Ville)
>> Changes since v2:
>> - Move the optimization to a separate commit. (Ville)
>>
>> Signed-off-by: Maarten Lankhorst <maarten.lankhorst@linux.intel.com>
>> Fixes: b44d5c0c105a ("drm/i915: Always wait for flip_done, v2.")
>> Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=102675
>> Testcase: kms_cursor_crc
>> Cc: Daniel Vetter <daniel.vetter@ffwll.ch>
>> Cc: Jani Nikula <jani.nikula@linux.intel.com>
>> Reported-by: Marta Löfstedt <marta.lofstedt@intel.com>
>> Cc: Marta Löfstedt <marta.lofstedt@intel.com>
>> Tested-by: Marta Löfstedt <marta.lofstedt@intel.com>
>> Cc: Ville Syrjälä <ville.syrjala@linux.intel.com>
>> ---
>> drivers/gpu/drm/i915/intel_display.c | 33 ++++++++++++++++-----------------
>> 1 file changed, 16 insertions(+), 17 deletions(-)
>>
>> diff --git a/drivers/gpu/drm/i915/intel_display.c b/drivers/gpu/drm/i915/intel_display.c
>> index 8599e425abb1..a85ca19a0c45 100644
>> --- a/drivers/gpu/drm/i915/intel_display.c
>> +++ b/drivers/gpu/drm/i915/intel_display.c
>> @@ -12517,21 +12517,10 @@ static int intel_atomic_commit(struct drm_device *dev,
>> struct drm_i915_private *dev_priv = to_i915(dev);
>> int ret = 0;
>>
>> - ret = drm_atomic_helper_setup_commit(state, nonblock);
>> - if (ret)
>> - return ret;
>> -
>> drm_atomic_state_get(state);
>> i915_sw_fence_init(&intel_state->commit_ready,
>> intel_atomic_commit_ready);
>>
>> - ret = intel_atomic_prepare_commit(dev, state);
>> - if (ret) {
>> - DRM_DEBUG_ATOMIC("Preparing state failed with %i\n", ret);
>> - i915_sw_fence_commit(&intel_state->commit_ready);
>> - return ret;
>> - }
>> -
>> /*
>> * The intel_legacy_cursor_update() fast path takes care
>> * of avoiding the vblank waits for simple cursor
>> @@ -12540,11 +12529,11 @@ static int intel_atomic_commit(struct drm_device *dev,
>> * updates happen during the correct frames. Gen9+ have
>> * double buffered watermarks and so shouldn't need this.
>> *
>> - * Do this after drm_atomic_helper_setup_commit() and
>> - * intel_atomic_prepare_commit() because we still want
>> - * to skip the flip and fb cleanup waits. Although that
>> - * does risk yanking the mapping from under the display
>> - * engine.
>> + * Unset state->legacy_cursor_update before the call to
>> + * drm_atomic_helper_setup_commit() because otherwise
>> + * drm_atomic_helper_wait_for_flip_done() is a noop and
>> + * we get FIFO underruns because we didn't wait
>> + * for vblank.
>> *
>> * FIXME doing watermarks and fb cleanup from a vblank worker
>> * (assuming we had any) would solve these problems.
>> @@ -12552,7 +12541,17 @@ static int intel_atomic_commit(struct drm_device *dev,
>> if (INTEL_GEN(dev_priv) < 9)
>> state->legacy_cursor_update = false;
>>
>> - ret = drm_atomic_helper_swap_state(state, true);
>> + ret = intel_atomic_prepare_commit(dev, state);
>> + if (ret) {
>> + DRM_DEBUG_ATOMIC("Preparing state failed with %i\n", ret);
>> + i915_sw_fence_commit(&intel_state->commit_ready);
>> + return ret;
>> + }
>> +
>> + ret = drm_atomic_helper_setup_commit(state, nonblock);
> Hmm. One thing I noticed here. Previously if this failed we just called
> i915_sw_fence_commit(). Now we will also call
> drm_atomic_helper_cleanup_planes(). Is that going to be a problem?
This is intentional, intel_atomic_prepare_commit calls prepare_planes,
if that succeeds we'll need to call cleanup_planes too.

Ordering of setup_commit and prepare_planes doesn't matter.
>> + if (!ret)
>> + ret = drm_atomic_helper_swap_state(state, true);
>> +
>> if (ret) {
>> i915_sw_fence_commit(&intel_state->commit_ready);
>>
>> --
>> 2.14.1