Re: [RFC] viafb: add interface for output device configuration

[Andrew Morton <akpm@linux-foundation.org>]

On Mon,  6 Sep 2010 22:48:10 +0000
Florian Tobias Schandinat <FlorianSchandinat@gmx.de> wrote:

> viafb: add interface for output device configuration
> 
> This patch extends the proc entry to contain a possibility to view and
> change the output devices for each IGA. This is useful for debugging
> output problems as it provides a reliable way to query which low level
> devices are active after VIAs output device configuration nightmare
> happended. It's as well suitable for daily use as one can change the
> output configuration on the fly for example to connect a projector.
> At the moment it's still unstable. The reason is that we have to handle
> a bunch of undocumented output devices (those without a proper name) and
> that this patch is the first step to collect and verify the needed
> information. Basically the only configuration change that is expected to
> work at the moment is switching output devices between IGA1 and IGA2.
> 
> ...
>  
> +u32 via_parse_odev(char *input, char **end)
> +{
> +	char *ptr = input;
> +	u32 odev = 0;
> +	bool next = true;
> +	int i, len;
> +
> +	while (next) {
> +		next = false;
> +		for (i = 0; i < ARRAY_SIZE(device_mapping); i++) {
> +			len = strlen(device_mapping[i].name);
> +			if (!strncmp(ptr, device_mapping[i].name, len)) {
> +				odev |= device_mapping[i].device;
> +				ptr += len;
> +				if (*ptr = ',') {
> +					ptr++;
> +					next = true;
> +				}
> +			}
> +		}
> +	}
> +
> +	*end = ptr;
> +	return odev;
> +}

So people must decrypt the above code

> +		iga1_entry = proc_mkdir("iga1", viafb_entry);
> +		shared->iga1_proc_entry = iga1_entry;
> +		proc_create("output_devices", 0, iga1_entry,
> +			&viafb_iga1_odev_proc_fops);
> +		iga2_entry = proc_mkdir("iga2", viafb_entry);
> +		shared->iga2_proc_entry = iga2_entry;
> +		proc_create("output_devices", 0, iga2_entry,
> +			&viafb_iga2_odev_proc_fops);
>  	}

to work out what to write into these?

Can we have a wee bit of documetnation, please?  At least in the
changelog, but Documentation/fb/viafb.txt would be a better place.