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

[Dmitry Baryshkov]

On Fri, Sep 11, 2026 at 11:51:06AM +0300, YİĞİTCAN KAVAKLI via B4 Relay wrote:
> From: YİĞİTCAN KAVAKLI <kavakliyigitcan@xxxxxxxxx>
> 
> 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 <kavakliyigitcan@xxxxxxxxx>
> ---
>  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