ok so there are some issues. First is DMA is not going to work properly.
This is incorrect
.max_transfer_sz = 65536,
This is a large waste of memory
.trans_queue_depth = 10,
You have doubled the memory use because of storing the function parameters in a structure and then placing those into another structure when the display is initialized. That consumes twice as much memory.
It’s hard to keep a strong focus on this running on something that has a very limited amount of resources. so doing things like this
mpdisplay_display_rotation_t ROTATIONS_320x480[4] = {
{320, 480, 0, 0, false, true, false},
{480, 320, 0, 0, true, false, false},
{320, 480, 0, 0, false, false, true},
{480, 320, 0, 0, true, true, true}
};
mpdisplay_display_rotation_t ROTATIONS_240x320[4] = {
{240, 320, 0, 0, false, false, false},
{320, 240, 0, 0, true, true, false},
{240, 320, 0, 0, false, true, true},
{320, 240, 0, 0, true, false, true}
};
mpdisplay_display_rotation_t ROTATIONS_170x320[4] = {
{170, 320, 35, 0, false, false, false},
{320, 170, 0, 35, true, true, false},
{170, 320, 35, 0, false, true, true},
{320, 170, 0, 35, true, false, true}
};
mpdisplay_display_rotation_t ROTATIONS_240x240[4] = {
{240, 240, 0, 0, false, false, false},
{240, 240, 0, 0, true, true, false},
{240, 240, 0, 80, false, true, true},
{240, 240, 80, 0, true, false, true}
};
mpdisplay_display_rotation_t ROTATIONS_135x240[4] = {
{135, 240, 52, 40, false, false, false},
{240, 135, 40, 53, true, true, false},
{135, 240, 53, 40, false, true, true},
{240, 135, 40, 52, true, false, true}
};
mpdisplay_display_rotation_t ROTATIONS_128x160[4] = {
{128, 160, 0, 0, false, false, false},
{160, 128, 0, 0, true, true, false},
{128, 160, 0, 0, false, true, true},
{160, 128, 0, 0, true, false, true}
};
mpdisplay_display_rotation_t ROTATIONS_80x160[4] = {
{80, 160, 26, 1, false, false, false},
{160, 80, 1, 26, true, true, false},
{80, 160, 26, 1, false, true, true},
{160, 80, 1, 26, true, false, true}
};
mpdisplay_display_rotation_t ROTATIONS_128x128[4] = {
{128, 128, 2, 1, false, false, false},
{128, 128, 1, 2, true, true, false},
{128, 128, 2, 3, false, true, true},
{128, 128, 3, 2, true, false, true}
};
mpdisplay_display_rotation_t *ROTATIONS[] = {
ROTATIONS_240x320, // default if no match
ROTATIONS_320x480,
ROTATIONS_170x320,
ROTATIONS_240x240,
ROTATIONS_135x240,
ROTATIONS_128x160,
ROTATIONS_80x160,
ROTATIONS_128x128,
NULL
};
consumes a lot of resources and those resources never get released because the allocation is done in the global namespace. The above consumes 384 bytes of memory when it is only going to get used a single time.
Returning the frame buffer as a bytearray is going to consume quite a bit more memory as well. Returning it as a memoryview or an an array.array would be a better thing to do, something that the size is not able to expand or contract. Giving that ability has cost. with the frame buffer it can stay as a fixed size because it is never going to change size.