Debug output

Debug output

[damateem]

There are a fair number of debug print statements in the V4L2 code. How
do I turn those on?

For instance, I'd like the following code to print

if ((vfd->debug & V4L2_DEBUG_IOCTL) &&
                !(vfd->debug & V4L2_DEBUG_IOCTL_ARG)) {
        v4l_print_ioctl(vfd->name, cmd);
        printk(KERN_CONT "\n");
    }

so I can trace the IOCTL calls.

Thanks,
David

Re: Debug output

[damateem]

Ok, if I set debug as follows

vfd->debug =V4L2_DEBUG_IOCTL | V4L2_DEBUG_IOCTL_ARG;

I can see the debug trace in dmesg, but this doesn't seem like the
correct way to set the flags.

What is the typical method of setting these debug flags?

Is this the best place to ask these type of questions?

Thanks,
David


On 11/30/2011 7:46 PM, damateem wrote:
> There are a fair number of debug print statements in the V4L2 code. How
> do I turn those on?
>
> For instance, I'd like the following code to print
>
> if ((vfd->debug & V4L2_DEBUG_IOCTL) &&
>                 !(vfd->debug & V4L2_DEBUG_IOCTL_ARG)) {
>         v4l_print_ioctl(vfd->name, cmd);
>         printk(KERN_CONT "\n");
>     }
>
> so I can trace the IOCTL calls.
>
> Thanks,
> David

Re: Debug output

[Mauro Carvalho Chehab]

On 01-12-2011 17:01, damateem wrote:
> Ok, if I set debug as follows
>
> vfd->debug =V4L2_DEBUG_IOCTL | V4L2_DEBUG_IOCTL_ARG;
>
> I can see the debug trace in dmesg, but this doesn't seem like the
> correct way to set the flags.

In general, what it is none is to add a debug modprobe parameter that
would enable those logs with something like:

static unsigned int debug;
module_param(debug, int, 0644);
MODULE_PARM_DESC(debug, "debug message mask (1 = ioctl, 2 = ioctl args)");


...
	vfd->debug = debug;

>
> What is the typical method of setting these debug flags?
>
> Is this the best place to ask these type of questions?
>
> Thanks,
> David
>
>
> On 11/30/2011 7:46 PM, damateem wrote:
>> There are a fair number of debug print statements in the V4L2 code. How
>> do I turn those on?
>>
>> For instance, I'd like the following code to print
>>
>> if ((vfd->debug&  V4L2_DEBUG_IOCTL)&&
>>                  !(vfd->debug&  V4L2_DEBUG_IOCTL_ARG)) {
>>          v4l_print_ioctl(vfd->name, cmd);
>>          printk(KERN_CONT "\n");
>>      }
>>
>> so I can trace the IOCTL calls.
>>
>> Thanks,
>> David
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