[Intel-gfx] [PATCH] drm/i915/dsi: unregister gmbus if LFP display was MIPI panel

[Lee, Shawn C]

On Thu, 16 Sep 2021, Jani Nikula <jani.nikula at linux.intel.com> wrote:
>On Thu, 16 Sep 2021, Lee Shawn C <shawn.c.lee at intel.com> wrote:
>> Gmbus driver would setup all Intel i2c GMBuses. But DDC bus may 
>> configured as gpio and reserved for MIPI driver to control panel power 
>> on/off sequence.
>>
>> Using i2c tool to communicate to peripherals via i2c interface 
>> reversed for gmbus(DDC). There will be some high/low pulse appear on 
>> DDC SCL and SDA (might be host sent out i2c slave address). MIPI panel 
>> would be impacted due to unexpected signal then caused abnormal 
>> display or shut down issue.
>
>Just a quick reply:
>
>So I don't know off the bat what the right solution is, but it's very obvious to me that we absolute can't go deleting gmbus adapters from DSI code.
>
>
>BR,
>Jani.
>

Create a new function in gmbus driver that allow to remove a given gmbus adapter. And DSI driver used it to unregister particular gmbus.
It looks to me more reasonable for DSI and gmbus driver. What do you think?

Best regards,
Shawn

>>
>> Cc: Jani Nikula <jani.nikula at linux.intel.com>
>> Cc: Vandita Kulkarni <vandita.kulkarni at intel.com>
>> Cc: Cooper Chiou <cooper.chiou at intel.com>
>> Cc: William Tseng <william.tseng at intel.com>
>> Signed-off-by: Lee Shawn C <shawn.c.lee at intel.com>
>> ---
>>  drivers/gpu/drm/i915/display/icl_dsi.c | 14 ++++++++++++++
>>  1 file changed, 14 insertions(+)
>>
>> diff --git a/drivers/gpu/drm/i915/display/icl_dsi.c 
>> b/drivers/gpu/drm/i915/display/icl_dsi.c
>> index 060bc8fb0d30..d2504e291fcb 100644
>> --- a/drivers/gpu/drm/i915/display/icl_dsi.c
>> +++ b/drivers/gpu/drm/i915/display/icl_dsi.c
>> @@ -1999,6 +1999,7 @@ void icl_dsi_init(struct drm_i915_private *dev_priv)
>>  	struct intel_connector *intel_connector;
>>  	struct drm_connector *connector;
>>  	struct drm_display_mode *fixed_mode;
>> +	struct intel_gmbus *bus;
>>  	enum port port;
>>  
>>  	if (!intel_bios_is_dsi_present(dev_priv, &port)) @@ -2092,6 +2093,19 
>> @@ void icl_dsi_init(struct drm_i915_private *dev_priv)
>>  	icl_dphy_param_init(intel_dsi);
>>  
>>  	icl_dsi_add_properties(intel_connector);
>> +
>> +	/*
>> +	 * DDC bus may configured as gpio and reserved for MIPI driver
>> +	 * to control panel power on/off sequence. so, unregister gmbus
>> +	 * if MIPI was LFP display.
>> +	 */
>> +	bus = &dev_priv->gmbus[GMBUS_PIN_1_BXT];
>> +	i2c_del_adapter(&bus->adapter);
>> +
>> +	if (dev_priv->vbt.dsi.config->dual_link) {
>> +		bus = &dev_priv->gmbus[GMBUS_PIN_2_BXT];
>> +		i2c_del_adapter(&bus->adapter);
>> +	}
>>  	return;
>>  
>>  err:
>
>--
>Jani Nikula, Intel Open Source Graphics Center