* [PATCH 0/2] staging: vchiq: Minor fixups to CONFIG_VCHIQ_CDEV
@ 2021-07-28 18:37 Ojaswin Mujoo
2021-07-28 18:37 ` [PATCH 1/2] staging: vchiq: Set $CONFIG_VCHIQ_CDEV to be enabled by default Ojaswin Mujoo
2021-07-28 18:37 ` [PATCH 2/2] staging: vchiq: Add details to $CONFIG_VCHIQ_CDEV help text Ojaswin Mujoo
0 siblings, 2 replies; 11+ messages in thread
From: Ojaswin Mujoo @ 2021-07-28 18:37 UTC (permalink / raw)
To: nsaenz, gregkh, stefan.wahren
Cc: dan.carpenter, phil, linux-arm-kernel, linux-staging, linux-kernel
Hi everyone,
The patchset performs some minor fixups to the CONFIG_VCHIQ_CDEV config
option defined in /staging/vc04_services/Kconfig. (Introduced in [1])
Summary:
Patch 1: Enable the config by default to be more consistent with how
cdev creation worked before this config was introduced
Patch 2: Add some more details to the config's help text
Please let me know if any changes are required.
Thank you!
Ojaswin
[1] https://lore.kernel.org/r/846c424dd4aae14d1cc28c8f30877a06e2b7dd10.1626882325.git.ojaswin98@gmail.com
Ojaswin Mujoo (2):
staging: vchiq: Set $CONFIG_VCHIQ_CDEV to be enabled by default
staging: vchiq: Add details to $CONFIG_VCHIQ_CDEV help text
drivers/staging/vc04_services/Kconfig | 9 +++++++--
1 file changed, 7 insertions(+), 2 deletions(-)
--
2.25.1
^ permalink raw reply [flat|nested] 11+ messages in thread* [PATCH 1/2] staging: vchiq: Set $CONFIG_VCHIQ_CDEV to be enabled by default 2021-07-28 18:37 [PATCH 0/2] staging: vchiq: Minor fixups to CONFIG_VCHIQ_CDEV Ojaswin Mujoo @ 2021-07-28 18:37 ` Ojaswin Mujoo 2021-07-28 18:45 ` Greg KH 2021-07-28 18:37 ` [PATCH 2/2] staging: vchiq: Add details to $CONFIG_VCHIQ_CDEV help text Ojaswin Mujoo 1 sibling, 1 reply; 11+ messages in thread From: Ojaswin Mujoo @ 2021-07-28 18:37 UTC (permalink / raw) To: nsaenz, gregkh, stefan.wahren Cc: dan.carpenter, phil, linux-arm-kernel, linux-staging, linux-kernel Before this config was defined, the cdev used to be created unconditionally. When an earlier commit introduced this config, the default behavior was set to disabled, which might surprise some unsuspecting users. Hence, make this config default to 'Y' to be more backward consistent. Signed-off-by: Ojaswin Mujoo <ojaswin98@gmail.com> --- drivers/staging/vc04_services/Kconfig | 1 + 1 file changed, 1 insertion(+) diff --git a/drivers/staging/vc04_services/Kconfig b/drivers/staging/vc04_services/Kconfig index 63caa6818d37..2b70c37cdd09 100644 --- a/drivers/staging/vc04_services/Kconfig +++ b/drivers/staging/vc04_services/Kconfig @@ -23,6 +23,7 @@ if BCM2835_VCHIQ config VCHIQ_CDEV bool "VCHIQ Character Driver" + default y help Enable the creation of VCHIQ character driver to help communicate with the Videocore platform. -- 2.25.1 ^ permalink raw reply related [flat|nested] 11+ messages in thread
* Re: [PATCH 1/2] staging: vchiq: Set $CONFIG_VCHIQ_CDEV to be enabled by default 2021-07-28 18:37 ` [PATCH 1/2] staging: vchiq: Set $CONFIG_VCHIQ_CDEV to be enabled by default Ojaswin Mujoo @ 2021-07-28 18:45 ` Greg KH 2021-07-28 20:06 ` Ojaswin Mujoo 0 siblings, 1 reply; 11+ messages in thread From: Greg KH @ 2021-07-28 18:45 UTC (permalink / raw) To: Ojaswin Mujoo Cc: nsaenz, stefan.wahren, dan.carpenter, phil, linux-arm-kernel, linux-staging, linux-kernel On Thu, Jul 29, 2021 at 12:07:16AM +0530, Ojaswin Mujoo wrote: > Before this config was defined, the cdev used to be created > unconditionally. When an earlier commit introduced this config, the > default behavior was set to disabled, which might surprise some > unsuspecting users. Hence, make this config default to 'Y' to be more > backward consistent. > > Signed-off-by: Ojaswin Mujoo <ojaswin98@gmail.com> > --- > drivers/staging/vc04_services/Kconfig | 1 + > 1 file changed, 1 insertion(+) > > diff --git a/drivers/staging/vc04_services/Kconfig b/drivers/staging/vc04_services/Kconfig > index 63caa6818d37..2b70c37cdd09 100644 > --- a/drivers/staging/vc04_services/Kconfig > +++ b/drivers/staging/vc04_services/Kconfig > @@ -23,6 +23,7 @@ if BCM2835_VCHIQ > > config VCHIQ_CDEV > bool "VCHIQ Character Driver" > + default y default y is only if the machine will not work without this option. Is that the case here? If not, then please do not have this as the default. thanks, greg k-h ^ permalink raw reply [flat|nested] 11+ messages in thread
* Re: [PATCH 1/2] staging: vchiq: Set $CONFIG_VCHIQ_CDEV to be enabled by default 2021-07-28 18:45 ` Greg KH @ 2021-07-28 20:06 ` Ojaswin Mujoo 2021-07-28 20:21 ` Stefan Wahren 0 siblings, 1 reply; 11+ messages in thread From: Ojaswin Mujoo @ 2021-07-28 20:06 UTC (permalink / raw) To: Greg KH Cc: nsaenz, stefan.wahren, dan.carpenter, phil, linux-arm-kernel, linux-staging, linux-kernel On Wed, Jul 28, 2021 at 08:45:55PM +0200, Greg KH wrote: > On Thu, Jul 29, 2021 at 12:07:16AM +0530, Ojaswin Mujoo wrote: > > Before this config was defined, the cdev used to be created > > unconditionally. When an earlier commit introduced this config, the > > default behavior was set to disabled, which might surprise some > > unsuspecting users. Hence, make this config default to 'Y' to be more > > backward consistent. > > > > Signed-off-by: Ojaswin Mujoo <ojaswin98@gmail.com> > > --- > > drivers/staging/vc04_services/Kconfig | 1 + > > 1 file changed, 1 insertion(+) > > > > diff --git a/drivers/staging/vc04_services/Kconfig b/drivers/staging/vc04_services/Kconfig > > index 63caa6818d37..2b70c37cdd09 100644 > > --- a/drivers/staging/vc04_services/Kconfig > > +++ b/drivers/staging/vc04_services/Kconfig > > @@ -23,6 +23,7 @@ if BCM2835_VCHIQ > > > > config VCHIQ_CDEV > > bool "VCHIQ Character Driver" > > + default y > > > default y is only if the machine will not work without this option. > Is that the case here? If not, then please do not have this as the > default. Got it Greg. From my testing, the Raspberry Pi does seem to boot correctly without this although some userspace libraries might not work. Since the machine itself works, I guess I'll drop this patch. Thank you! Ojaswin > > thanks, > > greg k-h ^ permalink raw reply [flat|nested] 11+ messages in thread
* Re: [PATCH 1/2] staging: vchiq: Set $CONFIG_VCHIQ_CDEV to be enabled by default 2021-07-28 20:06 ` Ojaswin Mujoo @ 2021-07-28 20:21 ` Stefan Wahren 2021-07-29 14:20 ` Ojaswin Mujoo 0 siblings, 1 reply; 11+ messages in thread From: Stefan Wahren @ 2021-07-28 20:21 UTC (permalink / raw) To: Ojaswin Mujoo, Greg KH Cc: nsaenz, dan.carpenter, phil, linux-arm-kernel, linux-staging, linux-kernel Am 28.07.21 um 22:06 schrieb Ojaswin Mujoo: > On Wed, Jul 28, 2021 at 08:45:55PM +0200, Greg KH wrote: >> On Thu, Jul 29, 2021 at 12:07:16AM +0530, Ojaswin Mujoo wrote: >>> Before this config was defined, the cdev used to be created >>> unconditionally. When an earlier commit introduced this config, the >>> default behavior was set to disabled, which might surprise some >>> unsuspecting users. Hence, make this config default to 'Y' to be more >>> backward consistent. >>> >>> Signed-off-by: Ojaswin Mujoo <ojaswin98@gmail.com> >>> --- >>> drivers/staging/vc04_services/Kconfig | 1 + >>> 1 file changed, 1 insertion(+) >>> >>> diff --git a/drivers/staging/vc04_services/Kconfig b/drivers/staging/vc04_services/Kconfig >>> index 63caa6818d37..2b70c37cdd09 100644 >>> --- a/drivers/staging/vc04_services/Kconfig >>> +++ b/drivers/staging/vc04_services/Kconfig >>> @@ -23,6 +23,7 @@ if BCM2835_VCHIQ >>> >>> config VCHIQ_CDEV >>> bool "VCHIQ Character Driver" >>> + default y >> >> default y is only if the machine will not work without this option. >> Is that the case here? If not, then please do not have this as the >> default. > Got it Greg. > > From my testing, the Raspberry Pi does seem to boot correctly without > this although some userspace libraries might not work. > > Since the machine itself works, I guess I'll drop this patch. The idea is good, but the patch needs improvement :) Acceptable solution might be that BCM2835_VCHIQ selects VCHIQ_CDEV. > > Thank you! > Ojaswin >> thanks, >> >> greg k-h > _______________________________________________ > linux-arm-kernel mailing list > linux-arm-kernel@lists.infradead.org > http://lists.infradead.org/mailman/listinfo/linux-arm-kernel ^ permalink raw reply [flat|nested] 11+ messages in thread
* Re: [PATCH 1/2] staging: vchiq: Set $CONFIG_VCHIQ_CDEV to be enabled by default 2021-07-28 20:21 ` Stefan Wahren @ 2021-07-29 14:20 ` Ojaswin Mujoo 0 siblings, 0 replies; 11+ messages in thread From: Ojaswin Mujoo @ 2021-07-29 14:20 UTC (permalink / raw) To: Stefan Wahren Cc: Greg KH, nsaenz, dan.carpenter, phil, linux-arm-kernel, linux-staging, linux-kernel On Wed, Jul 28, 2021 at 10:21:41PM +0200, Stefan Wahren wrote: > Am 28.07.21 um 22:06 schrieb Ojaswin Mujoo: > > On Wed, Jul 28, 2021 at 08:45:55PM +0200, Greg KH wrote: > >> On Thu, Jul 29, 2021 at 12:07:16AM +0530, Ojaswin Mujoo wrote: > >>> Before this config was defined, the cdev used to be created > >>> unconditionally. When an earlier commit introduced this config, the > >>> default behavior was set to disabled, which might surprise some > >>> unsuspecting users. Hence, make this config default to 'Y' to be more > >>> backward consistent. > >>> > >>> Signed-off-by: Ojaswin Mujoo <ojaswin98@gmail.com> > >>> --- > >>> drivers/staging/vc04_services/Kconfig | 1 + > >>> 1 file changed, 1 insertion(+) > >>> > >>> diff --git a/drivers/staging/vc04_services/Kconfig b/drivers/staging/vc04_services/Kconfig > >>> index 63caa6818d37..2b70c37cdd09 100644 > >>> --- a/drivers/staging/vc04_services/Kconfig > >>> +++ b/drivers/staging/vc04_services/Kconfig > >>> @@ -23,6 +23,7 @@ if BCM2835_VCHIQ > >>> > >>> config VCHIQ_CDEV > >>> bool "VCHIQ Character Driver" > >>> + default y > >> > >> default y is only if the machine will not work without this option. > >> Is that the case here? If not, then please do not have this as the > >> default. > > Got it Greg. > > > > From my testing, the Raspberry Pi does seem to boot correctly without > > this although some userspace libraries might not work. > > > > Since the machine itself works, I guess I'll drop this patch. > > The idea is good, but the patch needs improvement :) > > Acceptable solution might be that BCM2835_VCHIQ selects VCHIQ_CDEV. Thanks for the suggestion, Stefan. So on testing with select, it seems like select defines a hard reverse dependency i.e if BCM2835_VCHIQ=y then VCHIQ_CDEV=y and it can't be set to n. Checking the Kconfig launguae doc, I found that we could use "imply" to define weak reverse dependencies, such that BCM2835_VCHIQ=y auto selects VCHIQ_CDEV=y but we can also change it back to n if required. I tested this out and it seems to work fine. I believe we can se imply here as it better suits the use case. Thank you, Ojaswin > > > > > Thank you! > > Ojaswin > >> thanks, > >> > >> greg k-h > > _______________________________________________ > > linux-arm-kernel mailing list > > linux-arm-kernel@lists.infradead.org > > http://lists.infradead.org/mailman/listinfo/linux-arm-kernel > ^ permalink raw reply [flat|nested] 11+ messages in thread
* [PATCH 2/2] staging: vchiq: Add details to $CONFIG_VCHIQ_CDEV help text 2021-07-28 18:37 [PATCH 0/2] staging: vchiq: Minor fixups to CONFIG_VCHIQ_CDEV Ojaswin Mujoo 2021-07-28 18:37 ` [PATCH 1/2] staging: vchiq: Set $CONFIG_VCHIQ_CDEV to be enabled by default Ojaswin Mujoo @ 2021-07-28 18:37 ` Ojaswin Mujoo 2021-07-28 18:46 ` Greg KH 1 sibling, 1 reply; 11+ messages in thread From: Ojaswin Mujoo @ 2021-07-28 18:37 UTC (permalink / raw) To: nsaenz, gregkh, stefan.wahren Cc: dan.carpenter, phil, linux-arm-kernel, linux-staging, linux-kernel 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@gmail.com> --- 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'. endif -- 2.25.1 ^ permalink raw reply related [flat|nested] 11+ messages in thread
* Re: [PATCH 2/2] staging: vchiq: Add details to $CONFIG_VCHIQ_CDEV help text 2021-07-28 18:37 ` [PATCH 2/2] staging: vchiq: Add details to $CONFIG_VCHIQ_CDEV help text Ojaswin Mujoo @ 2021-07-28 18:46 ` Greg KH 2021-07-28 20:00 ` Ojaswin Mujoo 0 siblings, 1 reply; 11+ messages in thread From: Greg KH @ 2021-07-28 18:46 UTC (permalink / raw) To: Ojaswin Mujoo Cc: nsaenz, stefan.wahren, dan.carpenter, phil, linux-arm-kernel, linux-staging, linux-kernel 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@gmail.com> > --- > 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? thanks, greg k-h ^ permalink raw reply [flat|nested] 11+ messages in thread
* Re: [PATCH 2/2] staging: vchiq: Add details to $CONFIG_VCHIQ_CDEV help text 2021-07-28 18:46 ` Greg KH @ 2021-07-28 20:00 ` Ojaswin Mujoo 2021-07-28 20:39 ` Stefan Wahren 0 siblings, 1 reply; 11+ messages in thread From: Ojaswin Mujoo @ 2021-07-28 20:00 UTC (permalink / raw) To: Greg KH Cc: nsaenz, stefan.wahren, dan.carpenter, phil, linux-arm-kernel, linux-staging, linux-kernel 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@gmail.com> > > --- > > 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? This config option merely adds a cdev which exposes the the core driver's functionality to userspace. Regards, Ojaswin > > thanks, > > greg k-h ^ permalink raw reply [flat|nested] 11+ messages in thread
* Re: [PATCH 2/2] staging: vchiq: Add details to $CONFIG_VCHIQ_CDEV help text 2021-07-28 20:00 ` Ojaswin Mujoo @ 2021-07-28 20:39 ` Stefan Wahren 2021-07-29 13:47 ` Ojaswin Mujoo 0 siblings, 1 reply; 11+ messages in thread From: Stefan Wahren @ 2021-07-28 20:39 UTC (permalink / raw) To: Ojaswin Mujoo, Greg KH Cc: nsaenz, dan.carpenter, phil, linux-arm-kernel, linux-staging, linux-kernel 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@gmail.com> >>> --- >>> 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@lists.infradead.org > http://lists.infradead.org/mailman/listinfo/linux-arm-kernel ^ permalink raw reply [flat|nested] 11+ messages in thread
* Re: [PATCH 2/2] staging: vchiq: Add details to $CONFIG_VCHIQ_CDEV help text 2021-07-28 20:39 ` Stefan Wahren @ 2021-07-29 13:47 ` Ojaswin Mujoo 0 siblings, 0 replies; 11+ messages in thread From: Ojaswin Mujoo @ 2021-07-29 13:47 UTC (permalink / raw) To: Stefan Wahren Cc: Greg KH, nsaenz, dan.carpenter, phil, linux-arm-kernel, linux-staging, linux-kernel 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@gmail.com> > >>> --- > >>> 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@lists.infradead.org > > http://lists.infradead.org/mailman/listinfo/linux-arm-kernel > ^ permalink raw reply [flat|nested] 11+ messages in thread
end of thread, other threads:[~2021-07-29 14:21 UTC | newest] Thread overview: 11+ messages (download: mbox.gz / follow: Atom feed) -- links below jump to the message on this page -- 2021-07-28 18:37 [PATCH 0/2] staging: vchiq: Minor fixups to CONFIG_VCHIQ_CDEV Ojaswin Mujoo 2021-07-28 18:37 ` [PATCH 1/2] staging: vchiq: Set $CONFIG_VCHIQ_CDEV to be enabled by default Ojaswin Mujoo 2021-07-28 18:45 ` Greg KH 2021-07-28 20:06 ` Ojaswin Mujoo 2021-07-28 20:21 ` Stefan Wahren 2021-07-29 14:20 ` Ojaswin Mujoo 2021-07-28 18:37 ` [PATCH 2/2] staging: vchiq: Add details to $CONFIG_VCHIQ_CDEV help text Ojaswin Mujoo 2021-07-28 18:46 ` Greg KH 2021-07-28 20:00 ` Ojaswin Mujoo 2021-07-28 20:39 ` Stefan Wahren 2021-07-29 13:47 ` Ojaswin Mujoo
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