limpens
Posts: 38
Joined: Thu Sep 13, 2012 1:15 pm

Kernel option to get camera working

Sat May 18, 2013 10:11 am

@JamesH,

Can you confirm CONFIG_BCM_VC_CMA is required to get the camera up and running?

Without that option in my kernel vcgencmd reports the camera is detected/supported, but I did have problems retrieving an image (if I recollect correct something about no resource space or some cryptic message like that).

Compared the config.gz from the raspbian kernel against my own kernel config and this option did make a difference.

Another question,

I've read somewhere it is possible to disable the camera led by using a config.txt option. Is it possible to change the led behavior using a kernel / proc / sysfs interface?

Eric

jamesh
Raspberry Pi Engineer & Forum Moderator
Raspberry Pi Engineer & Forum Moderator
Posts: 32137
Joined: Sat Jul 30, 2011 7:41 pm

Re: Kernel option to get camera working

Sat May 18, 2013 11:23 am

I don't think CMA is necessary . in fact I think there are issues with using CMA in certain circumstances unrelated to camera so the current advice is not to use it (AFAIR)

You probably can adjust the LED, it's just on a GPIO. Don't know the details.
Principal Software Engineer at Raspberry Pi Ltd.
Working in the Applications Team.

limpens
Posts: 38
Joined: Thu Sep 13, 2012 1:15 pm

Re: Kernel option to get camera working

Sat May 18, 2013 11:36 am

Might enabling this option change some of the other (cma related) behavior?
I couldn't get the camera working properly with a couple of cma related config.txt settings. When the kernel was build using the above mentioned option, the camera works ok.

When I removed the cma_lwm, cma_hwm and cma_offline_start the camera wasn't working. Until adding CONFIG_BCM_VC_CMA=y (and still including the 3 cma_ parameters), it did work ok.

Camera led isn't controlled by the firmware as far as you know?

Eric

edit:

just powered up with the 3 cma_ parameters in the config.txt
Pi didn't boot. Removed the entries and no problems.

jamesh
Raspberry Pi Engineer & Forum Moderator
Raspberry Pi Engineer & Forum Moderator
Posts: 32137
Joined: Sat Jul 30, 2011 7:41 pm

Re: Kernel option to get camera working

Sat May 18, 2013 12:54 pm

limpens wrote:Might enabling this option change some of the other (cma related) behavior?
I couldn't get the camera working properly with a couple of cma related config.txt settings. When the kernel was build using the above mentioned option, the camera works ok.

When I removed the cma_lwm, cma_hwm and cma_offline_start the camera wasn't working. Until adding CONFIG_BCM_VC_CMA=y (and still including the 3 cma_ parameters), it did work ok.

Camera led isn't controlled by the firmware as far as you know?

Eric

edit:

just powered up with the 3 cma_ parameters in the config.txt
Pi didn't boot. Removed the entries and no problems.
As I said, CMA is known not to work correctly 100% yet, so you shouldn't really be using it.
Principal Software Engineer at Raspberry Pi Ltd.
Working in the Applications Team.

limpens
Posts: 38
Joined: Thu Sep 13, 2012 1:15 pm

Re: Kernel option to get camera working

Sat May 18, 2013 12:57 pm

jamesh wrote:
limpens wrote:Might enabling this option change some of the other (cma related) behavior?
I couldn't get the camera working properly with a couple of cma related config.txt settings. When the kernel was build using the above mentioned option, the camera works ok.

When I removed the cma_lwm, cma_hwm and cma_offline_start the camera wasn't working. Until adding CONFIG_BCM_VC_CMA=y (and still including the 3 cma_ parameters), it did work ok.

Camera led isn't controlled by the firmware as far as you know?

Eric

edit:

just powered up with the 3 cma_ parameters in the config.txt
Pi didn't boot. Removed the entries and no problems.
As I said, CMA is known not to work correctly 100% yet, so you shouldn't really be using it.
Will do. Cheers.

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