linux-kernel - Re: [PATCH] [media] cec: add missing inline stubs

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Message-ID: <975908ec-c95c-170d-e7b7-31a810ad82ba@xs4all.nl>
Date:	Fri, 1 Jul 2016 17:22:32 +0200
From:	Hans Verkuil <hverkuil@...all.nl>
To:	Arnd Bergmann <arnd@...db.de>
Cc:	Hans Verkuil <hans.verkuil@...co.com>,
	Mauro Carvalho Chehab <mchehab@...nel.org>,
	linux-media@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH] [media] cec: add missing inline stubs

On 07/01/2016 05:13 PM, Arnd Bergmann wrote:
> On Friday, July 1, 2016 4:35:09 PM CEST Hans Verkuil wrote:
>> On 07/01/2016 01:19 PM, Arnd Bergmann wrote:
>>> The linux/cec.h header file contains empty inline definitions for
>>> a subset of the API for the case in which CEC is not enabled,
>>> however we have driver that call other functions as well:
>>>
>>> drivers/media/i2c/adv7604.c: In function 'adv76xx_cec_tx_raw_status':
>>> drivers/media/i2c/adv7604.c:1956:3: error: implicit declaration of function 'cec_transmit_done' [-Werror=implicit-function-declaration]
>>> drivers/media/i2c/adv7604.c: In function 'adv76xx_cec_isr':
>>> drivers/media/i2c/adv7604.c:2012:4: error: implicit declaration of function 'cec_received_msg' [-Werror=implicit-function-declaration]
>>> drivers/media/i2c/adv7604.c: In function 'adv76xx_probe':
>>> drivers/media/i2c/adv7604.c:3482:20: error: implicit declaration of function 'cec_allocate_adapter' [-Werror=implicit-function-declaration]
>>
>> I don't understand this. These calls are under #if IS_ENABLED(CONFIG_VIDEO_ADV7842_CEC),
>> and that should be 0 if MEDIA_CEC is not selected.
>>
>> Am I missing some weird config combination?
> 
> This must have been a build error I ran into before your patch, when I
> had this one applied locally instead:
> 
> diff --git a/include/media/cec.h b/include/media/cec.h
> index c462f9b44074..564a6a06bed7 100644
> --- a/include/media/cec.h
> +++ b/include/media/cec.h
> @@ -187,7 +187,7 @@ static inline bool cec_is_sink(const struct cec_adapter *adap)
>  	return adap->phys_addr == 0;
>  }
>  
> -#if IS_ENABLED(CONFIG_MEDIA_CEC)
> +#if IS_REACHABLE(CONFIG_MEDIA_CEC)
>  struct cec_adapter *cec_allocate_adapter(const struct cec_adap_ops *ops,
>  		void *priv, const char *name, u32 caps, u8 available_las,
>  		struct device *parent);
> 
> because that was hiding the declarations when the code could not
> reach it. With your newer patch that is not possible any more.
> 
> I also wasn't aware that each of these already had their own Kconfig
> symbols. Could we just do this instead of your patch then:
> 
> diff --git a/drivers/media/i2c/Kconfig b/drivers/media/i2c/Kconfig
> index ce9006e10a30..73e047220905 100644
> --- a/drivers/media/i2c/Kconfig
> +++ b/drivers/media/i2c/Kconfig
> @@ -222,6 +222,7 @@ config VIDEO_ADV7604
>  config VIDEO_ADV7604_CEC
>  	bool "Enable Analog Devices ADV7604 CEC support"
>  	depends on VIDEO_ADV7604 && MEDIA_CEC
> +	depends on VIDEO_ADV7604=m || MEDIA_CEC=y
>  	---help---
>  	  When selected the adv7604 will support the optional
>  	  HDMI CEC feature.
> @@ -243,6 +244,7 @@ config VIDEO_ADV7842
>  config VIDEO_ADV7842_CEC
>  	bool "Enable Analog Devices ADV7842 CEC support"
>  	depends on VIDEO_ADV7842 && MEDIA_CEC
> +	depends on VIDEO_ADV7842=m || MEDIA_CEC=y
>  	---help---
>  	  When selected the adv7842 will support the optional
>  	  HDMI CEC feature.
> @@ -475,6 +477,7 @@ config VIDEO_ADV7511
>  config VIDEO_ADV7511_CEC
>  	bool "Enable Analog Devices ADV7511 CEC support"
>  	depends on VIDEO_ADV7511 && MEDIA_CEC
> +	depends on VIDEO_ADV7511=m || MEDIA_CEC=y
>  	---help---
>  	  When selected the adv7511 will support the optional
>  	  HDMI CEC feature.
> diff --git a/drivers/media/platform/vivid/Kconfig b/drivers/media/platform/vivid/Kconfig
> index 8e6918c5c87c..8e31146d079a 100644
> --- a/drivers/media/platform/vivid/Kconfig
> +++ b/drivers/media/platform/vivid/Kconfig
> @@ -26,6 +26,7 @@ config VIDEO_VIVID
>  config VIDEO_VIVID_CEC
>  	bool "Enable CEC emulation support"
>  	depends on VIDEO_VIVID && MEDIA_CEC
> +	depends on VIDEO_VIVID=m || MEDIA_CEC=y
>  	---help---
>  	  When selected the vivid module will emulate the optional
>  	  HDMI CEC feature.
> 
> which is still not overly nice, but it manages to avoid the
> IS_REACHABLE() check and it lets MEDIA_CEC be a module.

The only IS_REACHABLE is for the RC_CORE check, and that should remain.

With my patch MEDIA_CEC can remain a module provided MEDIA_SUPPORT is also
a module. All drivers depending on MEDIA_CEC also depend on MEDIA_SUPPORT,
so that works.

As I mentioned in a previous post, this will change in the future but while
it is in staging I prefer to keep it like this.

Regards,

	Hans