Re: [PATCH] amdgpu/dc: Use DRM new-style object iterators.

[Maarten Lankhorst <maarten.lankhorst@linux.intel.com>]

Op 11-10-17 om 22:40 schreef Harry Wentland:
> On 2017-10-11 03:46 PM, Maarten Lankhorst wrote:
>> Op 11-10-17 om 20:55 schreef Leo:
>>>
>>> On 2017-10-11 10:30 AM, Maarten Lankhorst wrote:
>>>> Op 11-10-17 om 16:24 schreef sunpeng.li@amd.com:
>>>>> From: "Leo (Sunpeng) Li" <sunpeng.li@amd.com>
>>>>>
>>>>> Use the correct for_each_new/old_* iterators instead of for_each_*
>>>>>
>>>>> List of affected functions:
>>>>>
>>>>> amdgpu_dm_find_first_crtc_matching_connector: use for_each_new
>>>>>      - Old from_state_var flag was always choosing the new state
>>>>>
>>>>> amdgpu_dm_display_resume: use for_each_new
>>>>>      - drm_atomic_helper_duplicate_state is called during suspend to
>>>>>        cache the state
>>>>>      - It sets 'state' within the state triplet to 'new_state'
>>>>>
>>>>> amdgpu_dm_commit_planes: use for_each_old
>>>>>      - Called after the state was swapped (via atomic commit tail)
>>>>>
>>>>> amdgpu_dm_atomic_commit: use for_each_new
>>>>>      - Called before the state is swapped
>>>>>
>>>>> amdgpu_dm_atomic_commit_tail: use for_each_old
>>>>>      - Called after the state was swapped
>>>>>
>>>>> dm_update_crtcs_state: use for_each_new
>>>>>      - Called before the state is swapped (via atomic check)
>>>>>
>>>>> amdgpu_dm_atomic_check: use for_each_new
>>>>>      - Called before the state is swapped
>>>>>
>>>>> Also fix some typos.
>>>>>
>>>>> crct -> crtc
>>>>> undersacn -> underscan
>>>>>
>>>>> Signed-off-by: Leo (Sunpeng) Li <sunpeng.li@amd.com>
>>>>> ---
>>>>>
>>>>> Hi Dave,
>>>>>
>>>>> This patch goes on top of your fixup for new api's patch. Please feel
>>>>> free to squash them.
>>>>>
>>>>> Thanks,
>>>>> Leo
>>>>>
>>>>>   drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c | 38 +++++++++--------------
>>>>>   drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.h |  5 ++-
>>>>>   2 files changed, 16 insertions(+), 27 deletions(-)
>>>>>
>>>>> diff --git a/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c b/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c
>>>>> index 9bfe1f9..9394558 100644
>>>>> --- a/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c
>>>>> +++ b/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c
>>>>> @@ -568,25 +568,17 @@ static int dm_suspend(void *handle)
>>>>>       return ret;
>>>>>   }
>>>>>   -struct amdgpu_dm_connector *amdgpu_dm_find_first_crct_matching_connector(
>>>>> +struct amdgpu_dm_connector *amdgpu_dm_find_first_crtc_matching_connector(
>>>>>       struct drm_atomic_state *state,
>>>>> -    struct drm_crtc *crtc,
>>>>> -    bool from_state_var)
>>>>> +    struct drm_crtc *crtc)
>>>>>   {
>>>>>       uint32_t i;
>>>>>       struct drm_connector_state *conn_state;
>>>>>       struct drm_connector *connector;
>>>>>       struct drm_crtc *crtc_from_state;
>>>>>   -    for_each_new_connector_in_state(
>>>>> -        state,
>>>>> -        connector,
>>>>> -        conn_state,
>>>>> -        i) {
>>>>> -        crtc_from_state =
>>>>> -            from_state_var ?
>>>>> -                conn_state->crtc :
>>>>> -                connector->state->crtc;
>>>>> +    for_each_new_connector_in_state(state, connector, conn_state, i) {
>>>>> +        crtc_from_state = conn_state->crtc;
>>>> Please assign crtc_from_state here with drm_atomic_get_(new/old)_crtc_state.
>>> We're trying to fetch a drm_crtc from a drm_connector_state, I don't think the state getters are applicable here.
>>>
>>> Also, the function should really be named 'find_first_connector_matching_crtc'. I'll fix that.
>> Oh I misunderstood. But in general derefencing $obj->state should be frowned upon. If you ever want to support atomic flip depth > 1,
>> all those references should be gone from your driver, and replaced with get_old/new_state..
> If I understand correctly this is the forward-looking way of how we get the
> state now? I still see plenty of $obj->state in i915 and other drivers.
>
> Any objections to doing this as a follow-up patch?
>
> What's atomic flip depth > 1?

That we allow multiple uncompleted nonblocking atomic commits to the same crtc,
which requires that during commit, $obj->state is not the same as
new_$obj_state any more. It can be set to an even newer state, but the current
commit has to set the state that is in state->$obj[i].new_state. This can be
obtained with either the iterators, or drm_atomic_get_new_$obj_state.

This is why we we got rid of the old iterators, get_existing_state and $obj->state
were no longer sufficient for this.

Using drm_atomic_get_old/new_obj_state should be a separate patch, but can be fixed
opportunistically.

But something like

for_each_old_crtc_in_state(...) {
	new_crtc_state = crtc->state

	....
}

should definitely be fixed in this patch. It's what the iterators are for. :)

I know i915 is still dereferencing $obj->state, but we're trying to slowly fix these
when we come across them. This usually involves passing the correct state object up
the callchain, which can be quite deep.

Cheers,
Maarten

> Harry
>
>>>>
>>>>>           if (crtc_from_state == crtc)
>>>>>               return to_amdgpu_dm_connector(connector);
>>>>> @@ -3890,7 +3882,7 @@ static void amdgpu_dm_commit_planes(struct drm_atomic_state *state,
>>>>>       unsigned long flags;
>>>>>         /* update planes when needed */
>>>>> -    for_each_new_plane_in_state(state, plane, old_plane_state, i) {
>>>>> +    for_each_old_plane_in_state(state, plane, old_plane_state, i) {
>>>>>           struct drm_plane_state *plane_state = plane->state;
>>>>>           struct drm_crtc *crtc = plane_state->crtc;
>>>>>           struct drm_framebuffer *fb = plane_state->fb;
>>>> Use for_each_oldnew_*_in_state
>>>>> @@ -4024,7 +4016,7 @@ void amdgpu_dm_atomic_commit_tail(
>>>>>       dm_state = to_dm_atomic_state(state);
>>>>>         /* update changed items */
>>>>> -    for_each_new_crtc_in_state(state, crtc, old_crtc_state, i) {
>>>>> +    for_each_old_crtc_in_state(state, crtc, old_crtc_state, i) {
>>>>>           struct amdgpu_crtc *acrtc = to_amdgpu_crtc(crtc);
>>>>>           struct drm_crtc_state *new_state = crtc->state;
>>>> Same.
>>> Good points, it seems like there's quite a few places where drm interfaces can be used. Thanks for pointing this out.
>>>
>>> Leo
>>>
>>>>>   @@ -4113,11 +4105,9 @@ void amdgpu_dm_atomic_commit_tail(
>>>>>               new_acrtc_state = to_dm_crtc_state(new_crtcs[i]->base.state);
>>>>>                 new_stream = new_acrtc_state->stream;
>>>>> -            aconnector =
>>>>> -                amdgpu_dm_find_first_crct_matching_connector(
>>>>> +            aconnector = amdgpu_dm_find_first_crtc_matching_connector(
>>>>>                       state,
>>>>> -                    &new_crtcs[i]->base,
>>>>> -                    false);
>>>>> +                    &new_crtcs[i]->base);
>>>>>               if (!aconnector) {
>>>>>                   DRM_DEBUG_DRIVER("Atomic commit: Failed to find connector for acrtc id:%d "
>>>>>                        "skipping freesync init\n",
>>>>> @@ -4150,8 +4140,8 @@ void amdgpu_dm_atomic_commit_tail(
>>>>>           }
>>>>>       }
>>>>>   -    /* Handle scaling and undersacn changes*/
>>>>> -    for_each_new_connector_in_state(state, connector, old_conn_state, i) {
>>>>> +    /* Handle scaling and underscan changes*/
>>>>> +    for_each_old_connector_in_state(state, connector, old_conn_state, i) {
>>>>>           struct amdgpu_dm_connector *aconnector = to_amdgpu_dm_connector(connector);
>>>>>           struct dm_connector_state *con_new_state =
>>>>>                   to_dm_connector_state(aconnector->base.state);
>>>> Same here..
>>>>> @@ -4205,7 +4195,7 @@ void amdgpu_dm_atomic_commit_tail(
>>>>>       }
>>>>>         /* update planes when needed per crtc*/
>>>>> -    for_each_new_crtc_in_state(state, pcrtc, old_crtc_state, j) {
>>>>> +    for_each_old_crtc_in_state(state, pcrtc, old_crtc_state, j) {
>>>>>           new_acrtc_state = to_dm_crtc_state(pcrtc->state);
>>>> Same.
>>>>>           if (new_acrtc_state->stream)
>>>>> @@ -4218,7 +4208,7 @@ void amdgpu_dm_atomic_commit_tail(
>>>>>        * mark consumed event for drm_atomic_helper_commit_hw_done
>>>>>        */
>>>>>       spin_lock_irqsave(&adev->ddev->event_lock, flags);
>>>>> -    for_each_new_crtc_in_state(state, crtc, old_crtc_state, i) {
>>>>> +    for_each_old_crtc_in_state(state, crtc, old_crtc_state, i) {
>>>>>           struct amdgpu_crtc *acrtc = to_amdgpu_crtc(crtc);
>>>>>             if (acrtc->base.state->event)
>>>> Same. You're dereferencing crtc->state
>>>>> @@ -4402,7 +4392,7 @@ static int dm_update_crtcs_state(
>>>>>           new_acrtc_state = to_dm_crtc_state(crtc_state);
>>>>>           acrtc = to_amdgpu_crtc(crtc);
>>>>>   -        aconnector = amdgpu_dm_find_first_crct_matching_connector(state, crtc, true);
>>>>> +        aconnector = amdgpu_dm_find_first_crtc_matching_connector(state, crtc);
>>>>>             /* TODO This hack should go away */
>>>>>           if (aconnector) {
>>>>> @@ -4715,7 +4705,7 @@ int amdgpu_dm_atomic_check(struct drm_device *dev,
>>>>>        if (ret)
>>>>>            goto fail;
>>>>>   -    /* Check scaling and undersacn changes*/
>>>>> +    /* Check scaling and underscan changes*/
>>>>>       /*TODO Removed scaling changes validation due to inability to commit
>>>>>        * new stream into context w\o causing full reset. Need to
>>>>>        * decide how to handle.
>>>>> diff --git a/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.h b/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.h
>>>>> index 630e6cd..c1b77bd 100644
>>>>> --- a/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.h
>>>>> +++ b/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.h
>>>>> @@ -226,10 +226,9 @@ extern const struct amdgpu_ip_block_version dm_ip_block;
>>>>>   void amdgpu_dm_update_connector_after_detect(
>>>>>       struct amdgpu_dm_connector *aconnector);
>>>>>   -struct amdgpu_dm_connector *amdgpu_dm_find_first_crct_matching_connector(
>>>>> +struct amdgpu_dm_connector *amdgpu_dm_find_first_crtc_matching_connector(
>>>>>       struct drm_atomic_state *state,
>>>>> -    struct drm_crtc *crtc,
>>>>> -    bool from_state_var);
>>>>> +    struct drm_crtc *crtc);
>>>>>       struct amdgpu_framebuffer;
>>>>

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