<html> <head> <base href="https://bugs.freedesktop.org/"> </head> <body> <div> <a class="bz_bug_link bz_status_NEW " title="NEW - [i915][BYT] Blank screen on MIPI panel" href="https://bugs.freedesktop.org/show_bug.cgi?id=101205#c5">Comment # 5</a> on <a class="bz_bug_link bz_status_NEW " title="NEW - [i915][BYT] Blank screen on MIPI panel" href="https://bugs.freedesktop.org/show_bug.cgi?id=101205">bug 101205</a> from <a class="email" href="mailto:dimitry@cos.flag.org" title="Innocent Bystander <dimitry@cos.flag.org>"> Innocent Bystander</a> <pre>Sprinkling a few printks in the kernel I've discovered that in the file `intel_bios.c` inside the function `parse_mipi_sequence()` a call to `find_panel_sequence_block()` here: <a href="https://cgit.freedesktop.org/drm/drm-tip/tree/drivers/gpu/drm/i915/intel_bios.c#n984">https://cgit.freedesktop.org/drm/drm-tip/tree/drivers/gpu/drm/i915/intel_bios.c#n984</a> returns 2-byte long sequence block with the the first seq_id set to 0 (MIPI_SEQ_END). This causes `intel_dsi_vbt_exec_sequence()` in `intel_dsi_vbt.c` to simply return here: <a href="https://cgit.freedesktop.org/drm/drm-tip/tree/drivers/gpu/drm/i915/intel_dsi_vbt.c#n429">https://cgit.freedesktop.org/drm/drm-tip/tree/drivers/gpu/drm/i915/intel_dsi_vbt.c#n429</a> I am really just shooting in the dark here, as I've no clue what all of this means. My guess is these are some sort of initialization sequences for the MIPI panel. On the other hand, on the working unit the size of the sequence block is 1350 and it contains seq_ids: 1, 5, 2, 3 and 4, which would be MIPI_SEQ_{DEASSERT_RESET,ASSERT_RESET,INIT_OTP,DISPLAY_ON,DISPLAY_OFF}. If somebody could point me in the right direction, I would very much appreciate that.</pre> </div> <hr> You are receiving this mail because: <ul> <li>You are the assignee for the bug.</li> <li>You are on the CC list for the bug.</li> <li>You are the QA Contact for the bug.</li> </ul> </body> </html>