From: Alexandre Courbot <acourbot@nvidia.com>
To: Grant Likely <grant.likely@secretlab.ca>
Cc: Linus Walleij <linus.walleij@linaro.org>,
Arnd Bergmann <arnd@arndb.de>,
linux-arch <linux-arch@vger.kernel.org>,
"linux-arm-kernel@lists.infradead.org"
<linux-arm-kernel@lists.infradead.org>,
Linux Kernel Mailing List <linux-kernel@vger.kernel.org>
Subject: Re: [PATCH 8/9] gpiolib: use gpio_chips list in gpio_to_desc
Date: Sat, 9 Feb 2013 23:21:56 +0900 [thread overview]
Message-ID: <CAAVeFuK39k322MeQuzLDibGDSdidrhzqwstSWOPWwCy41Ehg-Q@mail.gmail.com> (raw)
In-Reply-To: <20130209095803.61C653E2CF2@localhost>
On Sat, Feb 9, 2013 at 6:58 PM, Grant Likely <grant.likely@secretlab.ca> wrote:
> I'm actually going to NAK this one. This is a hot path. Having a O(1)
> lookup from gpio number to gpio desc is important. I know you want to be
> rid of the gpio_desc table entirely, but in this case I think it is
> warranted. However, you can change the gpio_desc table to be a table of
> pointers to gpio_descs instead of a table of gpio_descs. That would save
> a lot of memory since unused GPIOs wouldn't have gpio_descs associated
> with them. It is also the mechanism used by the IRQ subsystem.
That would work - what I don't like is that it still ends being a
fixed-size static array that is not necessarily tailored to the
platform's needs. But I understand you don't want to punish the users
of the integer-based API, even though the penalty should really be
neglectable here.
Well, maybe I can try to come again with this once everybody uses GPIO
descriptors instead of integers. ;)
Alex.
next prev parent reply other threads:[~2013-02-09 14:21 UTC|newest]
Thread overview: 63+ messages / expand[flat|nested] mbox.gz Atom feed top
2013-02-02 16:29 [PATCH 0/9] gpiolib: remove gpio_desc[] static array Alexandre Courbot
2013-02-02 16:29 ` Alexandre Courbot
2013-02-02 16:29 ` [PATCH 1/9] gpiolib: link all gpio_chips using a list Alexandre Courbot
2013-02-02 16:29 ` Alexandre Courbot
2013-02-05 17:00 ` Linus Walleij
2013-02-09 9:20 ` Grant Likely
2013-02-09 9:20 ` Grant Likely
2013-02-02 16:29 ` [PATCH 2/9] gpiolib: use gpio_chips list in gpiolib_sysfs_init Alexandre Courbot
2013-02-02 16:29 ` Alexandre Courbot
2013-02-05 17:04 ` Linus Walleij
2013-02-09 9:22 ` Grant Likely
2013-02-09 9:22 ` Grant Likely
2013-02-02 16:29 ` [PATCH 3/9] gpiolib: use gpio_chips list in gpiochip_find Alexandre Courbot
2013-02-02 16:29 ` Alexandre Courbot
2013-02-05 17:05 ` Linus Walleij
2013-02-09 9:25 ` Grant Likely
2013-02-09 9:25 ` Grant Likely
2013-02-02 16:29 ` [PATCH 4/9] gpiolib: use gpio_chips list in sysfs ops Alexandre Courbot
2013-02-02 16:29 ` Alexandre Courbot
2013-02-05 17:15 ` Linus Walleij
2013-02-05 17:15 ` Linus Walleij
2013-02-09 9:37 ` Grant Likely
2013-02-09 9:37 ` Grant Likely
2013-02-09 13:53 ` Alexandre Courbot
2013-02-02 16:29 ` [PATCH 5/9] gpiolib: use gpio_chips list in gpiochip_find_base Alexandre Courbot
2013-02-02 16:29 ` Alexandre Courbot
2013-02-05 17:21 ` Linus Walleij
2013-02-06 4:48 ` Alex Courbot
2013-02-09 9:47 ` Grant Likely
2013-02-09 9:47 ` Grant Likely
2013-02-02 16:29 ` [PATCH 6/9] gpiolib: use descriptors internally Alexandre Courbot
2013-02-02 16:29 ` Alexandre Courbot
2013-02-05 17:53 ` Linus Walleij
2013-02-07 6:57 ` Alexandre Courbot
2013-02-09 9:17 ` Grant Likely
2013-02-09 9:17 ` Grant Likely
2013-02-11 14:09 ` Linus Walleij
2013-02-11 15:40 ` Paul Mundt
2013-02-11 15:40 ` Paul Mundt
2013-02-11 17:39 ` Stephen Warren
2013-02-12 12:29 ` Linus Walleij
2013-02-12 15:59 ` Paul Mundt
2013-02-12 17:18 ` Arnd Bergmann
2013-02-09 13:11 ` Grant Likely
2013-02-09 13:11 ` Grant Likely
2013-02-09 14:15 ` Alexandre Courbot
2013-02-09 13:24 ` Grant Likely
2013-02-09 13:24 ` Grant Likely
2013-02-09 14:18 ` Alexandre Courbot
2013-02-02 16:29 ` [PATCH 7/9] gpiolib: let gpio_chip reference its descriptors Alexandre Courbot
2013-02-05 18:00 ` Linus Walleij
2013-02-09 13:28 ` Grant Likely
2013-02-02 16:29 ` [PATCH 8/9] gpiolib: use gpio_chips list in gpio_to_desc Alexandre Courbot
2013-02-05 18:01 ` Linus Walleij
2013-02-05 18:01 ` Linus Walleij
2013-02-09 9:58 ` Grant Likely
2013-02-09 9:58 ` Grant Likely
2013-02-09 14:21 ` Alexandre Courbot [this message]
2013-02-09 14:21 ` Alexandre Courbot
2013-02-09 14:37 ` Grant Likely
2013-02-02 16:29 ` [PATCH 9/9] gpiolib: dynamically allocate descriptors array Alexandre Courbot
2013-02-02 16:29 ` Alexandre Courbot
2013-02-05 18:02 ` Linus Walleij
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