| Message ID | 20240708-raspi-revision-v1-0-66e7e403e0b5@gmx.net |
|---|---|
| Headers | show |
| Series | ARM: Expose Raspberry Pi revision code in /proc/cpuinfo | expand |
Hi Jonathan, Am 08.07.24 um 01:08 schrieb Jonathan Neuschäfer: > Raspberry Pi boards have a "revision code", documented here: > > https://www.raspberrypi.com/documentation/computers/raspberry-pi.html#new-style-revision-codes AFAIK these revision codes mostly refer to the board and not to the CPU. The abuse of /proc/cpuinfo has been rejected in the past and from my understanding this applies also in this case. > This patch copies what the downstream kernel does and reads it from the > devicetree property /system/linux,revision. This enables some software > to work as intended on mainline kernels: > > https://github.com/hzeller/rpi-rgb-led-matrix/blob/a3eea997a9254b83ab2de97ae80d83588f696387/lib/gpio.cc#L247 This is a bad example because the application doesn't really care about the kernel and directly access the hardware registers via /dev/mem. A proper application would use the dedicated userspace API (GPIO Character Device or PWM). I would bet that the application does not work with the Raspberry Pi 5. Regards > > Signed-off-by: Jonathan Neuschäfer <j.neuschaefer@gmx.net> > --- > Jonathan Neuschäfer (2): > dt-bindings: arm: bcm2835: Specify /system/linux,revision property > ARM: bcm2835: Detect system revision > > Documentation/devicetree/bindings/arm/bcm/bcm2835.yaml | 12 ++++++++++++ > arch/arm/mach-bcm/board_bcm2835.c | 11 +++++++++++ > 2 files changed, 23 insertions(+) > --- > base-commit: 22a40d14b572deb80c0648557f4bd502d7e83826 > change-id: 20240707-raspi-revision-84dffdfaebce > > Best regards, > -- > Jonathan Neuschäfer <j.neuschaefer@gmx.net> >
On Mon, Jul 08, 2024 at 06:14:01PM +0200, Stefan Wahren wrote: > Hi Jonathan, > > Am 08.07.24 um 01:08 schrieb Jonathan Neuschäfer: > > Raspberry Pi boards have a "revision code", documented here: > > > > https://www.raspberrypi.com/documentation/computers/raspberry-pi.html#new-style-revision-codes > AFAIK these revision codes mostly refer to the board and not to the CPU. True. > The abuse of /proc/cpuinfo has been rejected in the past and from my > understanding this applies also in this case. Alright > > This patch copies what the downstream kernel does and reads it from the > > devicetree property /system/linux,revision. This enables some software > > to work as intended on mainline kernels: > > > > https://github.com/hzeller/rpi-rgb-led-matrix/blob/a3eea997a9254b83ab2de97ae80d83588f696387/lib/gpio.cc#L247 > This is a bad example because the application doesn't really care about > the kernel and directly access the hardware registers via /dev/mem. A > proper application would use the dedicated userspace API (GPIO Character > Device or PWM). Right > I would bet that the application does not work with the Raspberry Pi 5. Probably, yeah. Jonathan
Raspberry Pi boards have a "revision code", documented here: https://www.raspberrypi.com/documentation/computers/raspberry-pi.html#new-style-revision-codes This patch copies what the downstream kernel does and reads it from the devicetree property /system/linux,revision. This enables some software to work as intended on mainline kernels: https://github.com/hzeller/rpi-rgb-led-matrix/blob/a3eea997a9254b83ab2de97ae80d83588f696387/lib/gpio.cc#L247 Signed-off-by: Jonathan Neuschäfer <j.neuschaefer@gmx.net> --- Jonathan Neuschäfer (2): dt-bindings: arm: bcm2835: Specify /system/linux,revision property ARM: bcm2835: Detect system revision Documentation/devicetree/bindings/arm/bcm/bcm2835.yaml | 12 ++++++++++++ arch/arm/mach-bcm/board_bcm2835.c | 11 +++++++++++ 2 files changed, 23 insertions(+) --- base-commit: 22a40d14b572deb80c0648557f4bd502d7e83826 change-id: 20240707-raspi-revision-84dffdfaebce Best regards, -- Jonathan Neuschäfer <j.neuschaefer@gmx.net>