Re: [PATCH RFC 09/10] drm/msm/dsi: separate host link enable from video stream enable

On Fri, Sep 11, 2026 at 11:51:06AM +0300, YİĞİTCAN KAVAKLI via B4 Relay wrote:

From: YİĞİTCAN KAVAKLI <redacted>

In video mode DSI displays, enabling the host previously engaged the
hardware video engine immediately during atomic_pre_enable. When panel
prepare routines transmit initial DCS sleep-out and setup commands,
concurrent active video transmission causes DMA timeouts (-110).

Keep the DSI host in command mode during atomic_pre_enable to permit
clean panel preparation, and start video streaming in atomic_enable
after the panel has completed initialization.

I've not seen this kind of issue with the DSI mode panels. Do you have a
more exact issue description or a downstream reference? Is it the case
that the bootloader has configured the DSI host for the command mode
transfers and you are reconfiguring it for the video mode?

Signed-off-by: YİĞİTCAN KAVAKLI <redacted>
---
 drivers/gpu/drm/msm/dsi/dsi.h         |  1 +
 drivers/gpu/drm/msm/dsi/dsi_host.c    | 23 ++++++++++++-----------
 drivers/gpu/drm/msm/dsi/dsi_manager.c | 20 ++++++++++++++++++++
 3 files changed, 33 insertions(+), 11 deletions(-)

+	/* Keep DSI host in command mode (VID_MODE_EN = 0) during panel init
+	 * to allow clean DCS communication without premature video engine startup.
 	 */
+	dsi_op_mode_config(msm_host, false, true);

This sounds plausible, but I'd like to check it out.

+
 	msm_host->enabled = true;
 	return 0;
 }
 

-- 
With best wishes
Dmitry