Re: [PATCH v2 7/8] drm/display: Move HDMI helpers into display-helper module

[Thomas Zimmermann <tzimmermann@suse.de>]

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Hi

Am 20.04.22 um 14:26 schrieb Javier Martinez Canillas:
> On 4/20/22 14:21, Thomas Zimmermann wrote:
>> 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.
>>
> Right, but that wasn't my question. I wondered why for example DRM_DW_HDMI
> Kconfig needs to select both DRM_DISPLAY_HDMI_HELPER and DRM_DISPLAY_HELPER
> since DRM_DISPLAY_HDMI_HELPER already selects DRM_DISPLAY_HELPER.
> 

Oh, well. You found a bug. It should be 'depends on' instead of 'select'.

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

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