From: Pavel Machek <pavel@ucw.cz>
To: "H. Nikolaus Schaller" <hns@goldelico.com>
Cc: galak@codeaurora.org, andy.shevchenko@gmail.com,
Rob Herring <robh+dt@kernel.org>, Pawel Moll <pawel.moll@arm.com>,
Mark Rutland <mark.rutland@arm.com>,
Ian Campbell <ijc+devicetree@hellion.org.uk>,
Linus Walleij <linus.walleij@linaro.org>,
Alexandre Courbot <gnurou@gmail.com>,
devicetree@vger.kernel.org, linux-gpio@vger.kernel.org,
linux-kernel@vger.kernel.org, letux-kernel@openphoenux.org,
kernel@pyra-handheld.com
Subject: Re: [PATCH v7 3/3] gpio: pca953x: fix address calculation for pcal6524
Date: Wed, 23 May 2018 16:06:36 +0200 [thread overview]
Message-ID: <20180523140635.GB27215@amd> (raw)
In-Reply-To: <e70e83f07aebaf702fef90a9fac61e41d8b558b0.1526533188.git.hns@goldelico.com>
[-- Attachment #1: Type: text/plain, Size: 1809 bytes --]
On Thu 2018-05-17 06:59:49, H. Nikolaus Schaller wrote:
> The register constants are so far defined in a way that they fit
> for the pcal9555a when shifted by the number of banks, i.e. are
> multiplied by 2 in the accessor function.
>
> Now, the pcal6524 has 3 banks which means the relative offset
> is multiplied by 4 for the standard registers.
>
> Simply applying the bit shift to the extended registers gives
> a wrong result, since the base offset is already included in
> the offset.
>
> Therefore, we have to add code to the 24 bit accessor functions
> that adjusts the register number for these exended registers.
>
> The formula finally used was developed and proposed by
> Andy Shevchenko <andy.shevchenko@gmail.com>.
>
> Suggested-by: Andy Shevchenko <andy.shevchenko@gmail.com>
> Signed-off-by: H. Nikolaus Schaller <hns@goldelico.com>
> ---
> drivers/gpio/gpio-pca953x.c | 8 ++++++--
> 1 file changed, 6 insertions(+), 2 deletions(-)
>
> diff --git a/drivers/gpio/gpio-pca953x.c b/drivers/gpio/gpio-pca953x.c
> index c682921d7019..4ad553f4e41f 100644
> --- a/drivers/gpio/gpio-pca953x.c
> +++ b/drivers/gpio/gpio-pca953x.c
> @@ -222,9 +222,11 @@ static int pca957x_write_regs_16(struct pca953x_chip *chip, int reg, u8 *val)
> static int pca953x_write_regs_24(struct pca953x_chip *chip, int reg, u8 *val)
> {
> int bank_shift = fls((chip->gpio_chip.ngpio - 1) / BANK_SZ);
> + int addr = (reg & PCAL_GPIO_MASK) << bank_shift;
> + int pinctrl = (reg & PCAL_PINCTRL_MASK) << 1;
Is this reasonable to do on each register access? Compiler will not be
able to optimize out fls and shifts, right?
Pavel
--
(english) http://www.livejournal.com/~pavelmachek
(cesky, pictures) http://atrey.karlin.mff.cuni.cz/~pavel/picture/horses/blog.html
[-- Attachment #2: Digital signature --]
[-- Type: application/pgp-signature, Size: 181 bytes --]
next prev parent reply other threads:[~2018-05-23 14:06 UTC|newest]
Thread overview: 13+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-05-17 4:59 [PATCH v7 0/3] pcal6524 extensions and fixes for pca953x driver H. Nikolaus Schaller
2018-05-17 4:59 ` [PATCH v7 1/3] gpio: pca953x: set the PCA_PCAL flag also when matching by DT H. Nikolaus Schaller
2018-05-23 11:46 ` Linus Walleij
2018-05-17 4:59 ` [PATCH v7 2/3] gpio: pca953x: define masks for addressing common and extended registers H. Nikolaus Schaller
2018-05-23 11:47 ` Linus Walleij
2018-05-17 4:59 ` [PATCH v7 3/3] gpio: pca953x: fix address calculation for pcal6524 H. Nikolaus Schaller
2018-05-23 11:48 ` Linus Walleij
2018-05-23 14:06 ` Pavel Machek [this message]
2018-06-05 15:37 ` Andy Shevchenko
2018-06-05 20:39 ` Pavel Machek
2018-06-06 5:33 ` H. Nikolaus Schaller
2018-06-06 7:35 ` Pavel Machek
2018-05-19 18:58 ` [PATCH v7 0/3] pcal6524 extensions and fixes for pca953x driver Andy Shevchenko
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=20180523140635.GB27215@amd \
--to=pavel@ucw.cz \
--cc=andy.shevchenko@gmail.com \
--cc=devicetree@vger.kernel.org \
--cc=galak@codeaurora.org \
--cc=gnurou@gmail.com \
--cc=hns@goldelico.com \
--cc=ijc+devicetree@hellion.org.uk \
--cc=kernel@pyra-handheld.com \
--cc=letux-kernel@openphoenux.org \
--cc=linus.walleij@linaro.org \
--cc=linux-gpio@vger.kernel.org \
--cc=linux-kernel@vger.kernel.org \
--cc=mark.rutland@arm.com \
--cc=pawel.moll@arm.com \
--cc=robh+dt@kernel.org \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).