From: Richard Purdie <rpurdie@rpsys.net>
To: Johannes Berg <johannes@sipsolutions.net>
Cc: linuxppc-dev list <linuxppc-dev@ozlabs.org>
Subject: Re: [PATCH] convert powermac ide blink to new led infrastructure
Date: Wed, 28 Jun 2006 10:38:02 +0100 [thread overview]
Message-ID: <1151487483.15913.11.camel@localhost.localdomain> (raw)
In-Reply-To: <1151429483.597.12.camel@localhost>
On Tue, 2006-06-27 at 19:31 +0200, Johannes Berg wrote:
> > Looks good. Only one nit: in pmu_led_set(), you should be able to test
> > if the requested state is identical to the current one and do nothing
> > without taking the lock no ?
> >
> > Or does the upper level LED infrastructure takes care of it ?
>
> I don't know, Richard? But yeah, I can do that too.
The core doesn't do that. In some cases setting the LED is easier and
cheaper than checking a cached value. If setting the LED state is
expensive, it would be simple enough to implement value caching in the
driver.
Part of the problem is also that we provide several values to the driver
(brightness, power, blanking, device specific parameters) and it needs
to combine those values in a way that is only meaningful to the specific
driver.
Richard
next prev parent reply other threads:[~2006-06-28 9:56 UTC|newest]
Thread overview: 19+ messages / expand[flat|nested] mbox.gz Atom feed top
2006-06-06 23:05 [PATCH] convert powermac ide blink to new led infrastructure Johannes Berg
2006-06-08 0:28 ` Benjamin Herrenschmidt
2006-06-09 11:47 ` Johannes Berg
2006-06-09 11:56 ` Anton Blanchard
2006-06-09 12:01 ` Johannes Berg
2006-06-21 10:11 ` Johannes Berg
2006-06-27 7:50 ` Benjamin Herrenschmidt
2006-06-27 17:31 ` Johannes Berg
2006-06-28 9:38 ` Richard Purdie [this message]
2006-06-28 9:43 ` Johannes Berg
-- strict thread matches above, loose matches on Subject: below --
2006-04-28 14:49 Johannes Berg
2006-04-28 15:15 ` Johannes Berg
2006-04-29 9:27 ` Johannes Berg
2006-05-01 6:56 ` Benjamin Herrenschmidt
2006-05-01 8:59 ` Johannes Berg
2006-05-01 9:10 ` Benjamin Herrenschmidt
2006-05-01 9:25 ` Johannes Berg
2006-05-01 9:35 ` Benjamin Herrenschmidt
2006-05-01 21:19 ` Johannes Berg
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