Hi Peter.
(Hijacking this thread as I lost the orginal mails)
I found an unfortunate issue while recoding plane handling to use drm_atomic_helper_check_plane_state(). The driver rotates clockwise, which is not correct. I simply fixed it (patch 1/4), but maybe that will cause regressions for unsuspecting users who simply assumed that the clockwise rotation was correct? I don't know what to do about that? Adding an option to get the old broken behavior seems useless, wouldn't it be just as easy to just fix whatever app to rotate the other way instead of adding an option somewhere?
Hm, rotation support has been added before the standard rotation property was created, and at that time I assumed rotation was clockwise (which apparently was an unwise choice). Anyway, I don't have a solution for this problem, so I'll let Nicolas decide if it's acceptable to change the rotation behavior.
I have only tested this series on sama5d3, but I did check the docs for various other chips (sama5d2, sama5d4, sam9n12, sam9g15, sam9g35 and sam9x35) supported by the driver (relevant to patch 4/4).
I wonder if, when this code path is anyway touched, could benefit from drm_rect_rotate().
It is obviously not a simple replacement, but could it be used then I hope the resulting code is simpler.
Sam