[ek_ra8d1] Drop down lists cannot be opened if DAVE2D is enebled

[kisvegabor]

When opening the drop down list of the widgets demo the application crashes.

It works well if DAVE2D is disabled.

[jeremy-baker]

Seems the Dave2D receives a drawing task with target layer buffer address set to 0, this causes the Dave2D to write to an invalid location, and it doesn't complete (an error interrupt occurs). As a work around, if I put a check in the execute_drawing function, :-

if (NULL == u->base_unit.target_layer->buf)
{
    return;
}

Then the drop down list works with the Daver2D enabled. Not sure why a drawing task would have target layer buffer address set to 0

[kisvegabor]

In some cases LVGL creates new "layer"s where it draws some tasks. The buffer for these layers are not allocated immediately, but they should be allocated in the dispatcher when the the first draw task is drawn on them.

See here in the SW renderer.

[jeremy-baker]

I was missing the allocation of buffer for new "layers" I added it in this commit, and it fixed the drop down list issue :-

jeremy-baker/lvgl@ad485bb

[kisvegabor]

Thank you! Now it's not crashing but the upper and lower parts look strange. These are blended by lv_draw_layer which is not implemented in Dave2D now.

However it works well in the simulator so I believe it's not a core LVGL issue. Do you have any idea?

[jeremy-baker]

I have created a pull request, lvgl/lvgl#5060 this partially fixes the issue. The colour of the corners of the drop down list drawn by the Dave2D don't quite look correct still.

[kisvegabor]

Thank you for the PR!