On Wed, Jul 28, 2021 at 10:39:38PM +0200, Stefan Wahren wrote: > 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 > Hi Stefan Thanks for the brief, its good enough to help me get started. I've also been looking more closely into this driver in my free time lately and I can try to come up with a small summary to use as the help text. I'll add it in v2 of this patch. Regards, Ojaswin > > > > 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 >
