linux-kernel - Re: [RFC PATCHv3 1/4] drivers/otp: add initial support for OTP memory

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Date:	Fri, 25 Mar 2011 18:50:36 -0400
From:	Mike Frysinger <vapier@...too.org>
To:	Jamie Iles <jamie@...ieiles.com>
Cc:	linux-kernel@...r.kernel.org, gregkh@...e.de
Subject: Re: [RFC PATCHv3 1/4] drivers/otp: add initial support for OTP memory

On Fri, Mar 25, 2011 at 18:47, Jamie Iles wrote:
> On Fri, Mar 25, 2011 at 05:58:05PM -0400, Mike Frysinger wrote:
>> On Fri, Mar 25, 2011 at 13:14, Jamie Iles wrote:
>> > +/* We'll allow OTP devices to be named otpa-otpz. */
>> > +#define MAX_OTP_DEVICES                26
>>
>> mmm is that still true ?
>
> I think so - the actual devices should be otpa-otpz, but when you
> register regions they could be otpa1, otpa2, otpb1, otpb2 etc.
>
>>
>> > +static unsigned long registered_otp_map[BITS_TO_LONGS(MAX_OTP_DEVICES)];
>> > +static DEFINE_MUTEX(otp_register_mutex);
>>
>> do we really need this ?  if we let the minor number dictate
>> availability, then we can increment until that errors/wraps, and we
>> dont need to do any tracking ...
>
> OK, so it would be nice to get rid of this but afaict we still need to
> do some accounting of available minor numbers in the range that we've
> allocated.  We could do a simple increment % 255 for the minor number
> but if OTP devices are removed at runtime then that may get fragmented
> and we would need to do retries of device_register() which feels a bit
> too easy to mess up.
>
> Certainly allocating one major number for OTP devices then allocating
> the minors one by one would be much better than what I have now.
>
> We probably also want it so that if you remove the OTP device that has
> had regions called otpaN then reinsert it they doesn't suddenly become
> otpbN.

yeah that's true.  guess i'll leave it be then ;).

whatever naming is picked in /dev/ should match the stuff in /sys/ btw ...
-mike
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