Re: [PATCH v7 1/5] staging: vc04_services: vchiq_arm: Add new bus type and device type

[Greg KH <gregkh@linuxfoundation.org>]

On Tue, Jun 20, 2023 at 07:11:48PM +0530, Umang Jain wrote:
> The devices that the vchiq interface registers (bcm2835-audio,
> bcm2835-camera) are implemented and exposed by the VC04 firmware.
> The device tree describes the VC04 itself with the resources required
> to communicate with it through a mailbox interface. However, the
> vchiq interface registers these devices as platform devices. This
> also means the specific drivers for these devices are getting
> registered as platform drivers. This is not correct and a blatant
> abuse of platform device/driver.
> 
> Add a new bus type, vchiq_bus_type and device type (struct vchiq_device)
> which will be used to migrate child devices that the vchiq interfaces
> creates/registers from the platform device/driver.
> 
> Signed-off-by: Umang Jain <umang.jain@ideasonboard.com>
> ---
>  drivers/staging/vc04_services/Makefile        |  1 +
>  .../interface/vchiq_arm/vchiq_device.c        | 78 +++++++++++++++++++
>  .../interface/vchiq_arm/vchiq_device.h        | 43 ++++++++++
>  3 files changed, 122 insertions(+)
>  create mode 100644 drivers/staging/vc04_services/interface/vchiq_arm/vchiq_device.c
>  create mode 100644 drivers/staging/vc04_services/interface/vchiq_arm/vchiq_device.h
> 
> diff --git a/drivers/staging/vc04_services/Makefile b/drivers/staging/vc04_services/Makefile
> index 44794bdf6173..2d071e55e175 100644
> --- a/drivers/staging/vc04_services/Makefile
> +++ b/drivers/staging/vc04_services/Makefile
> @@ -5,6 +5,7 @@ vchiq-objs := \
>     interface/vchiq_arm/vchiq_core.o  \
>     interface/vchiq_arm/vchiq_arm.o \
>     interface/vchiq_arm/vchiq_debugfs.o \
> +   interface/vchiq_arm/vchiq_device.o \
>     interface/vchiq_arm/vchiq_connected.o \
>  
>  ifdef CONFIG_VCHIQ_CDEV
> diff --git a/drivers/staging/vc04_services/interface/vchiq_arm/vchiq_device.c b/drivers/staging/vc04_services/interface/vchiq_arm/vchiq_device.c
> new file mode 100644
> index 000000000000..e16279a25126
> --- /dev/null
> +++ b/drivers/staging/vc04_services/interface/vchiq_arm/vchiq_device.c
> @@ -0,0 +1,78 @@
> +// SPDX-License-Identifier: GPL-2.0 OR BSD-3-Clause

Code that directly interacts with the driver core can, for obvious
reasons, not be BSD-3 licensed, sorry.

Also, why is any of this dual licensed?  What good is any of that?  In
order for me to accept new dual-licensed code, it needs to be documented
in the changelog very very well as to exactly why this is required, as
the legal issues involved in maintaining dual-licensed code like this is
tricky and easy to get wrong (as proven here already in this patch...)

thanks,

greg k-h