Re: [Intel-gfx] [PATCH v3] drm/i915/dsi: transmit brightness command in HS state

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

On Thu, 11 Nov 2021, "Tseng, William" <william.tseng@intel.com> wrote:
> Noted.  Thanks for your consideration, Jani.

And pushed, thanks for the patch.

BR,
Jani.

>
> Regards
> William
>
> -----Original Message-----
> From: Jani Nikula <jani.nikula@linux.intel.com> 
> Sent: Wednesday, November 10, 2021 6:45 PM
> To: Tseng, William <william.tseng@intel.com>; intel-gfx@lists.freedesktop.org
> Cc: Tseng, William <william.tseng@intel.com>; Ville Syrjala <ville.syrjala@linux.intel.com>; Kulkarni, Vandita <vandita.kulkarni@intel.com>; Lee, Shawn C <shawn.c.lee@intel.com>; Chiou, Cooper <cooper.chiou@intel.com>
> Subject: Re: [PATCH v3] drm/i915/dsi: transmit brightness command in HS state
>
> On Wed, 10 Nov 2021, William Tseng <william.tseng@intel.com> 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@linux.intel.com>
>> Cc: Jani Nikula <jani.nikula@linux.intel.com>
>> Cc: Vandita Kulkarni <vandita.kulkarni@intel.com>
>> Cc: Lee Shawn C <shawn.c.lee@intel.com>
>> Cc: Cooper Chiou <cooper.chiou@intel.com>
>> Signed-off-by: William Tseng <william.tseng@intel.com>
>> ---
>>  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@intel.com>
>
> I'll push once CI results are in; had to request a re-run.
>
>
>
>>  	}
>>  }
>
> --
> Jani Nikula, Intel Open Source Graphics Center

-- 
Jani Nikula, Intel Open Source Graphics Center