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Subject: Re: [PATCH v2 -next] drm/vc4: Fix build error when CONFIG_DRM_VC4=y
 && CONFIG_RASPBERRYPI_FIRMWARE=m
To:     Maxime Ripard <maxime@cerno.tech>
CC:     <emma@anholt.net>, <airlied@linux.ie>, <daniel@ffwll.ch>,
        <dri-devel@lists.freedesktop.org>, <linux-kernel@vger.kernel.org>,
        <tangyizhou@huawei.com>
References: <20220325021831.2812735-1-zhengbin13@huawei.com>
 <20220325130541.tjxq4kjgmkaz32en@houat>
From:   "Zhengbin (OSKernel)" <zhengbin13@huawei.com>
Message-ID: <601a9682-6afc-d87b-cfa7-5c683271f7a5@huawei.com>
Date:   Mon, 28 Mar 2022 10:22:11 +0800
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On 2022/3/25 21:05, Maxime Ripard wrote:
> Hi,
>
> On Fri, Mar 25, 2022 at 10:18:31AM +0800, Zheng Bin wrote:
>> If CONFIG_DRM_VC4=y, CONFIG_RASPBERRYPI_FIRMWARE=m, CONFIG_COMPILE_TEST=n,
>> bulding fails:
>>
>> drivers/gpu/drm/vc4/vc4_drv.o: In function `vc4_drm_bind':
>> vc4_drv.c:(.text+0x320): undefined reference to `rpi_firmware_get'
>> vc4_drv.c:(.text+0x320): relocation truncated to fit: R_AARCH64_CALL26 against undefined symbol `rpi_firmware_get'
>> vc4_drv.c:(.text+0x34c): undefined reference to `rpi_firmware_property'
>> vc4_drv.c:(.text+0x34c): relocation truncated to fit: R_AARCH64_CALL26 against undefined symbol `rpi_firmware_property'
>> vc4_drv.c:(.text+0x354): undefined reference to `rpi_firmware_put'
>> vc4_drv.c:(.text+0x354): relocation truncated to fit: R_AARCH64_CALL26 against undefined symbol `rpi_firmware_put'
>>
>> Make DRM_VC4 depends on RASPBERRYPI_FIRMWARE || COMPILE_TEST to fix this.
>>
>> Fixes: c406ad5e4a85 ("drm/vc4: Notify the firmware when DRM is in charge")
>> Reported-by: Hulk Robot <hulkci@huawei.com>
>> Signed-off-by: Zheng Bin <zhengbin13@huawei.com>
>> ---
>> v2: follow Maxime's advise, add RASPBERRYPI_FIRMWARE as an additional depends
>>   drivers/gpu/drm/vc4/Kconfig | 1 +
>>   1 file changed, 1 insertion(+)
>>
>> diff --git a/drivers/gpu/drm/vc4/Kconfig b/drivers/gpu/drm/vc4/Kconfig
>> index de3424fed2fc..92d74ba7c449 100644
>> --- a/drivers/gpu/drm/vc4/Kconfig
>> +++ b/drivers/gpu/drm/vc4/Kconfig
>> @@ -2,6 +2,7 @@
>>   config DRM_VC4
>>   	tristate "Broadcom VC4 Graphics"
>>   	depends on ARCH_BCM || ARCH_BCM2835 || COMPILE_TEST
>> +	depends on RASPBERRYPI_FIRMWARE || COMPILE_TEST
> Why do we need the || COMPILE_TEST here?
>
> The rpi_firmware_get, _property and _put functions aren't define if
> RASPBERRYPI_FIRMWARE, so we need that dependency every time, even if
> COMPILE_TEST is set?

include/soc/bcm2835/raspberrypi-firmware.h

#if IS_ENABLED(CONFIG_RASPBERRYPI_FIRMWARE)

struct rpi_firmware *rpi_firmware_get(struct device_node 
*firmware_node);/_property/_put

#else??? -->empty function

 ?static inline struct rpi_firmware *rpi_firmware_get(struct device_node 
*firmware_node)/_property/_put
{
 ???????? return NULL;
 ?}
#endif


We can refer to drivers/pwm/Kconfig

config PWM_RASPBERRYPI_POE
 ???????? tristate "Raspberry Pi Firwmware PoE Hat PWM support"
 ???????? # Make sure not 'y' when RASPBERRYPI_FIRMWARE is 'm'. This can 
only
 ??????? # happen when COMPILE_TEST=y, hence the added 
!RASPBERRYPI_FIRMWARE.
 ???????? depends on RASPBERRYPI_FIRMWARE || (COMPILE_TEST && 
!RASPBERRYPI_FIRMWARE)? -->There is no need to add (&& 
!RASPBERRYPI_FIRMWARE)

>
> Maxime