QSPI mode skips RASET (0x2B) in draw_bitmap, breaking partial rendering (AEGHB-1425) #666

Answers checklist.

• I have read the documentation ESP-IDF Programming Guide and the issue is not addressed there.
• I have updated my IDF branch (master or release) to the latest version and checked that the issue is present there.
• I have searched the issue tracker for a similar issue and not found a similar issue.

General issue report

In panel_axs15231b_draw_bitmap(), the RASET command (0x2B) is skipped when use_qspi_interface is enabled:
// esp_lcd_axs15231b.c, line ~307
if (0 == axs15231b->flags.use_qspi_interface) {
tx_param(axs15231b, io, LCD_CMD_RASET, (uint8_t[]) {
(y_start >> 8) & 0xFF,
y_start & 0xFF,
((y_end - 1) >> 8) & 0xFF,
(y_end - 1) & 0xFF,
}, 4);
}
This means the panel never receives a Y-axis window command in QSPI mode. The driver relies on sequential writes starting from y=0 using RAMWR (0x2C) and RAMWRC (0x3C) continuation, which only works if frames are always written top-to-bottom from row 0.

Impact:
Partial rendering (LVGL's default mode — redrawing only dirty rectangles) does not work in QSPI mode. Any draw_bitmap call with y_start > 0 that is not part of a sequential top-to-bottom write will render to incorrect rows, producing garbled output.
The only workaround is full_refresh = true (sending the entire framebuffer every frame), which wastes bandwidth and CPU on rotation/copy even when only a small region changed.

Expected behavior:
RASET should be sent in QSPI mode as well, wrapped with the QSPI opcode just like CASET:
// RASET should always be sent, regardless of interface mode
tx_param(axs15231b, io, LCD_CMD_RASET, (uint8_t[]) {
(y_start >> 8) & 0xFF,
y_start & 0xFF,
((y_end - 1) >> 8) & 0xFF,
(y_end - 1) & 0xFF,
}, 4);
The tx_param() helper already handles QSPI opcode wrapping (LCD_OPCODE_WRITE_CMD), so there's no reason to skip RASET.

Question:
Is this an intentional workaround for a hardware limitation of the AXS15231B chip in QSPI mode, or an oversight? If it's a hardware limitation, it should be documented (e.g., in README or as a code comment), because it forces full_refresh on all QSPI users.