Re: [PATCH] staging: olpc_dcon.c: checkpatch.pl and style fixups

[Jordan Crouse]

On Sat, Apr 14, 2012 at 8:26 PM, Andres Salomon <dilinger@xxxxxxxxxx> wrote:
> On Sun, 15 Apr 2012 00:53:04 +0200 (CEST)
> Jesper Juhl <jj@xxxxxxxxxxxxx> wrote:
>
>> This patch removes the few checkpatch.pl issues that are currently
>> reported for this file.
>>
>> It makes these changes:
>>
>> 1. Quoted strings that were broken over multiple lines are put on a
>>    single line for easier grep'ability.
>>
>> 2. Add missing level to a printk().
>>
>> 3. A few casts have had their space between the cast and variable
>>    removed.
>>
>
> These first three look fine.
>
>
>> 4. Two msleep() calls with times <= 20 have been changed to
>>    usleep_range() calls instead since msleep(<=20) may sleep for 20ms
>>    (on 100Hz kernels for instance).
>>    Picking a value for the lower bound of the range was easy, that was
>>    just the value passed to msleep(). As for picking the upper bound
>>    of the sleep I just went with two times the lower bound, for no
>>    other reason than the fact that in both cases that value was <=20ms
>>    and the end result will in any case be closer to the intention than
>>    a 20ms sleep.
>
>
> That msleep(1) was replaced with a longer msleep and fewer dcon_read
> attempts in OLPC's XO-1.75 kernel.  The msleep(10) should probably be
> a shorter usleep (though we'd need to test it).  In general, this
> stuff was done to work around bugs in the dcon, and the timing of these
> bugs appears to differ (probably due to smbus timing) between the
> various OLPC platforms - XO-1 (x86 amd geode), XO-1.5 (x86 via), and
> XO-1.75 (arm armada 610).
>
> Given that, I'd prefer to leave these alone and figure out the proper
> values later (with lots of testing).  Mind resubmitting with the
> msleep changes removed?

For what little authority I might still have 3 years later, I ACK the other
changes and agree with Andres about the timing.  The Geode numbers
were arrived upon after careful testing and consultation with various
witch doctors.

Jordan
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