Am 28.07.21 um 22:00 schrieb Ojaswin Mujoo: > On Wed, Jul 28, 2021 at 08:46:51PM +0200, Greg KH wrote: >> On Thu, Jul 29, 2021 at 12:07:17AM +0530, Ojaswin Mujoo wrote: >>> Add some details to the Kconfig definition of $CONFIG_VCHIQ_CDEV to help >>> make the motive behind it a bit more clear. >>> >>> Signed-off-by: Ojaswin Mujoo <ojaswin98@xxxxxxxxx> >>> --- >>> drivers/staging/vc04_services/Kconfig | 8 ++++++-- >>> 1 file changed, 6 insertions(+), 2 deletions(-) >>> >>> diff --git a/drivers/staging/vc04_services/Kconfig b/drivers/staging/vc04_services/Kconfig >>> index 2b70c37cdd09..cb02d8a4cb74 100644 >>> --- a/drivers/staging/vc04_services/Kconfig >>> +++ b/drivers/staging/vc04_services/Kconfig >>> @@ -25,8 +25,12 @@ config VCHIQ_CDEV >>> bool "VCHIQ Character Driver" >>> default y >>> help >>> - Enable the creation of VCHIQ character driver to help >>> - communicate with the Videocore platform. >>> + Enable the creation of VCHIQ character driver to help communicate >>> + with the VideoCore platform. The cdev exposes ioctls used by >>> + userspace libraries and testing tools to interact with VideoCore. >>> + This can be set to 'N' if the VideoCore communication is not needed >>> + by userspace but only by other kernel modules (like bcm2835-audio). >>> + If not sure, set this to 'Y'. >> I still do not understand if I need this driver or not, and I have this >> hardware! What functionality does this driver accomplish? What is >> VideoCore? > Hey Greg, > > I believe I can add this under the CONFIG_BCM2835_VCHIQ config option, > as that enables the core driver that implements the functions to > communicate with VideoCore platform? Sorry, today i'm too tired to give a good explanation. VideoCore is the VPU inside the BCM283x SoC. It runs a firmware and VCHIQ provides a way to communicate with this firmware / VPU. The VCHIQ driver is required to get access to the audio jack and camera interface (see depending drivers). Unfortunately i don't have an application list by the hand which uses the CDEV interface for VCHIQ, please use this link [1] as a starting point. [1] - https://github.com/raspberrypi/userland > > This config option merely adds a cdev which exposes the the core > driver's functionality to userspace. > > Regards, > Ojaswin >> thanks, >> >> greg k-h > _______________________________________________ > linux-arm-kernel mailing list > linux-arm-kernel@xxxxxxxxxxxxxxxxxxx > http://lists.infradead.org/mailman/listinfo/linux-arm-kernel
