On Wed, 10 Nov 2021, William Tseng <william.tseng@xxxxxxxxx> wrote:
> In Video Mode, if DSI transcoder is set to transmit packets
> in LP Escape mode, screen flickering would be obseved when
> brightness commands are continuously and quickly transmitted
> to a panel.
>
> The problem may be resolved by changing the mode to transmit
> packets from Low Power to HS.
>
> Cc: Ville Syrjala <ville.syrjala@xxxxxxxxxxxxxxx>
> Cc: Jani Nikula <jani.nikula@xxxxxxxxxxxxxxx>
> Cc: Vandita Kulkarni <vandita.kulkarni@xxxxxxxxx>
> Cc: Lee Shawn C <shawn.c.lee@xxxxxxxxx>
> Cc: Cooper Chiou <cooper.chiou@xxxxxxxxx>
> Signed-off-by: William Tseng <william.tseng@xxxxxxxxx>
> ---
> drivers/gpu/drm/i915/display/intel_dsi_dcs_backlight.c | 4 ++++
> 1 file changed, 4 insertions(+)
>
> diff --git a/drivers/gpu/drm/i915/display/intel_dsi_dcs_backlight.c b/drivers/gpu/drm/i915/display/intel_dsi_dcs_backlight.c
> index f61ed82e8867..7d234429e71e 100644
> --- a/drivers/gpu/drm/i915/display/intel_dsi_dcs_backlight.c
> +++ b/drivers/gpu/drm/i915/display/intel_dsi_dcs_backlight.c
> @@ -71,6 +71,7 @@ static void dcs_set_backlight(const struct drm_connector_state *conn_state, u32
> u8 data[2] = {};
> enum port port;
> size_t len = panel->backlight.max > U8_MAX ? 2 : 1;
> + unsigned long mode_flags;
>
> if (len == 1) {
> data[0] = level;
> @@ -81,8 +82,11 @@ static void dcs_set_backlight(const struct drm_connector_state *conn_state, u32
>
> for_each_dsi_port(port, intel_dsi->dcs_backlight_ports) {
> dsi_device = intel_dsi->dsi_hosts[port]->device;
> + mode_flags = dsi_device->mode_flags;
> + dsi_device->mode_flags &= ~MIPI_DSI_MODE_LPM;
> mipi_dsi_dcs_write(dsi_device, MIPI_DCS_SET_DISPLAY_BRIGHTNESS,
> &data, len);
> + dsi_device->mode_flags = mode_flags;
I realize we don't really have a clear picture how to manage
->mode_flags or MIPI_DSI_MODE_LPM in particular, but this seems like the
safest option for now.
Reviewed-by: Jani Nikula <jani.nikula@xxxxxxxxx>
I'll push once CI results are in; had to request a re-run.
> }
> }
--
Jani Nikula, Intel Open Source Graphics Center
