Re: [PATCH/RFC v8 02/14] Documentation: leds: Add description of LED Flash class extension

From: Jacek Anaszewski
Date: Mon Dec 01 2014 - 08:59:09 EST

Hi Pavel,

On 12/01/2014 02:04 PM, Pavel Machek wrote:

How are faults cleared? Should it be list of strings, instead of
bitmask? We may want to add new fault modes in future...

Faults are cleared by reading the attribute. I will add this note.
There can be more than one fault at a time. I think that the bitmask
is a flexible solution. I don't see any troubles related to adding
new fault modes in the future, do you?

I do not think that "read attribute to clear" is good idea. Normally,
you'd want the error attribute world-readable, but you don't want
non-root users to clear the errors.

This is also V4L2_CID_FLASH_FAULT control semantics.
Moreover many devices clear the errors upon reading register.
I don't see anything wrong in the fact that an user can clear
an error. If the user has a permission to use a device then
it also should be allowed to clear the errors.

I am not sure if bitmask is good solution. I'd return space-separated
strings like "overtemp". That way, there's good chance that other LED
drivers would be able to use similar interface...

The format of a sysfs attribute should be concise.
The error codes are generic and map directly to the V4L2 Flash
error codes.

Best Regards,
Jacek Anaszewski
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