Re: [PATCH] Revert "drm/i915/dsi: Do display on sequence later on icl+"

[Jani Nikula <jani.nikula@linux.intel.com>]

On Tue, 16 Jan 2024, Ville Syrjala <ville.syrjala@linux.intel.com> wrote:
> From: Ville Syrjälä <ville.syrjala@linux.intel.com>
>
> This reverts commit 88b065943cb583e890324d618e8d4b23460d51a3.
>
> Lenovo 82TQ is unhappy if we do the display on sequence this
> late. The display output shows severe corruption.
>
> It's unclear if this is a failure on our part (perhaps
> something to do with sending commands in LP mode after HS
> /video mode transmission has been started? Though the backlight
> on command at least seems to work) or simply that there are
> some commands in the sequence that are needed to be done
> earlier (eg. could be some DSC init stuff?). If the latter
> then I don't think the current Windows code would work
> either, but maybe this was originally tested with an older
> driver, who knows.
>
> Root causing this fully would likely require a lot of
> experimentation which isn't really feasible without direct
> access to the machine, so let's just accept failure and
> go back to the original sequence.
>
> Cc: stable@vger.kernel.org
> Closes: https://gitlab.freedesktop.org/drm/intel/-/issues/10071
> Signed-off-by: Ville Syrjälä <ville.syrjala@linux.intel.com>

Acked-by: Jani Nikula <jani.nikula@intel.com>

> ---
>  drivers/gpu/drm/i915/display/icl_dsi.c | 3 +--
>  1 file changed, 1 insertion(+), 2 deletions(-)
>
> diff --git a/drivers/gpu/drm/i915/display/icl_dsi.c b/drivers/gpu/drm/i915/display/icl_dsi.c
> index ac456a2275db..eda4a8b88590 100644
> --- a/drivers/gpu/drm/i915/display/icl_dsi.c
> +++ b/drivers/gpu/drm/i915/display/icl_dsi.c
> @@ -1155,6 +1155,7 @@ static void gen11_dsi_powerup_panel(struct intel_encoder *encoder)
>  	}
>  
>  	intel_dsi_vbt_exec_sequence(intel_dsi, MIPI_SEQ_INIT_OTP);
> +	intel_dsi_vbt_exec_sequence(intel_dsi, MIPI_SEQ_DISPLAY_ON);
>  
>  	/* ensure all panel commands dispatched before enabling transcoder */
>  	wait_for_cmds_dispatched_to_panel(encoder);
> @@ -1255,8 +1256,6 @@ static void gen11_dsi_enable(struct intel_atomic_state *state,
>  	/* step6d: enable dsi transcoder */
>  	gen11_dsi_enable_transcoder(encoder);
>  
> -	intel_dsi_vbt_exec_sequence(intel_dsi, MIPI_SEQ_DISPLAY_ON);
> -
>  	/* step7: enable backlight */
>  	intel_backlight_enable(crtc_state, conn_state);
>  	intel_dsi_vbt_exec_sequence(intel_dsi, MIPI_SEQ_BACKLIGHT_ON);

-- 
Jani Nikula, Intel