Re: [PATCH v2 2/2] drivers: gpio: add virtio-gpio guest driver

["Enrico Weigelt, metux IT consult" <lkml@xxxxxxxxx>]

On 04.12.20 04:35, Jason Wang wrote:

>> --- a/drivers/gpio/Kconfig
>> +++ b/drivers/gpio/Kconfig
>> @@ -1615,6 +1615,15 @@ config GPIO_MOCKUP
>>         tools/testing/selftests/gpio/gpio-mockup.sh. Reference the
>> usage in
>>         it.
>>   +config GPIO_VIRTIO
>> +    tristate "VirtIO GPIO support"
>> +    depends on VIRTIO
> 
> 
> Let's use select, since there's no prompt for VIRTIO and it doesn't have
> any dependencies.

whoops, it's not that simple:

make: Entering directory '/home/nekrad/src/apu2-dev/pkg/kernel.apu2.git'
make[1]: Entering directory
'/home/nekrad/src/dk/DistroKit/platform-x86_64/build-target/linux-5.8.9-build'
  GEN     Makefile
drivers/gpu/drm/Kconfig:74:error: recursive dependency detected!
drivers/gpu/drm/Kconfig:74:	symbol DRM_KMS_HELPER is selected by
DRM_VIRTIO_GPU
drivers/gpu/drm/virtio/Kconfig:2:	symbol DRM_VIRTIO_GPU depends on VIRTIO
drivers/virtio/Kconfig:2:	symbol VIRTIO is selected by GPIO_VIRTIO
drivers/gpio/Kconfig:1618:	symbol GPIO_VIRTIO depends on GPIOLIB
drivers/gpio/Kconfig:14:	symbol GPIOLIB is selected by I2C_MUX_LTC4306
drivers/i2c/muxes/Kconfig:47:	symbol I2C_MUX_LTC4306 depends on I2C
drivers/i2c/Kconfig:8:	symbol I2C is selected by FB_DDC
drivers/video/fbdev/Kconfig:63:	symbol FB_DDC depends on FB
drivers/video/fbdev/Kconfig:12:	symbol FB is selected by DRM_KMS_FB_HELPER
drivers/gpu/drm/Kconfig:80:	symbol DRM_KMS_FB_HELPER depends on
DRM_KMS_HELPER

Seems that we can only depend on or select some symbol - we run into
huge trouble if thats mixed. Just changed DRM_VIRTIO_GPU to just select
VIRIO instead of depending on it, and now it works.

I've posted another patch for fixing drivers/gpu/drm/virtio/Kconfig
to use 'select' instead of 'depends on'.

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Enrico Weigelt, metux IT consult
Free software and Linux embedded engineering
info@xxxxxxxxx -- +49-151-27565287