Hi

Am 20.04.22 um 14:02 schrieb Javier Martinez Canillas:
> Hello Thomas,
> 
> On 4/20/22 13:08, Thomas Zimmermann wrote:
> 
> [snip]
> 
>> --- a/drivers/gpu/drm/bridge/synopsys/Kconfig
>> +++ b/drivers/gpu/drm/bridge/synopsys/Kconfig
>> @@ -1,6 +1,8 @@
>>   # SPDX-License-Identifier: GPL-2.0-only
>>   config DRM_DW_HDMI
>>   	tristate
>> +	select DRM_DISPLAY_HDMI_HELPER
>> +	select DRM_DISPLAY_HELPER
>>   	select DRM_KMS_HELPER
>>   	select REGMAP_MMIO
>>   	select CEC_CORE if CEC_NOTIFIER
> 
> [snip]
> 
>> +config DRM_DISPLAY_HDMI_HELPER
>> +	bool
>> +	select DRM_DISPLAY_HELPER
>> +	help
>> +	  DRM display helpers for HDMI.
>> +
> 
> Maybe you mentioned already when we discussed it in v1, but could
> you please remember me why we need to select both symbols for the
> drivers, even when DRM_DISPLAY_HELPER is already selected here ?
> 
> Or are select operations not transitive ?

DRM_DISPLAY_HELPER enables the module itself. It's tristate. 
DRM_DISPLAY_HDMI_HELPER, DRM_DISPLAY_DP_HELPER, etc are the individual 
features of the helper module. Each is a boolean.  Drivers can enable 
them according to their needs.  This split allows linking correctly in 
all cases, even if some drivers are built-in and others are modules. 
This didn't always work with the original patches.

Best regards
Thomas

> 

-- 
Thomas Zimmermann
Graphics Driver Developer
SUSE Software Solutions Germany GmbH
Maxfeldstr. 5, 90409 Nürnberg, Germany
(HRB 36809, AG Nürnberg)
Geschäftsführer: Ivo Totev