From: Andy Shevchenko <andy.shevchenko@gmail.com>
To: Mark Brown <broonie@kernel.org>
Cc: Linus Walleij <linus.walleij@linaro.org>,
Jay Fang <f.fangjian@huawei.com>,
"linux-spi@vger.kernel.org" <linux-spi@vger.kernel.org>,
"linux-gpio@vger.kernel.org" <linux-gpio@vger.kernel.org>,
"linuxarm@huawei.com" <linuxarm@huawei.com>,
"huangdaode@huawei.com" <huangdaode@huawei.com>,
"tangzihao1@hisilicon.com" <tangzihao1@hisilicon.com>
Subject: Re: [PATCH 0/2] spi: Correct CS GPIOs polarity when using GPIO descriptors
Date: Thu, 6 May 2021 15:17:03 +0300 [thread overview]
Message-ID: <CAHp75Vf3yvSJUcmugjs8mcbnRa=PPviqqSrgB+Yyq6QV+J+Sbg@mail.gmail.com> (raw)
In-Reply-To: <20210506113430.GB4642@sirena.org.uk>
On Thu, May 6, 2021 at 2:35 PM Mark Brown <broonie@kernel.org> wrote:
> On Thu, May 06, 2021 at 02:24:17PM +0300, Andy Shevchenko wrote:
> > On Thursday, May 6, 2021, Linus Walleij <linus.walleij@linaro.org> wrote:
>
> > > Curious that ACPI has SPI CS as always active high,
>
> > Here I didn’t get what exactly you are pointing out. GPIOs are active high,
> > due to historical reasons. Otherwise SPI CS depends on the actual hardware
> > and may be (most of the cases?) active low.
>
> SPI chip selects are almost always active low - the signal is often
> written nCS or /CS for that reason.
Exactly, and it's not altered with ACPI. That's the whole point of
keeping it active high for _GPIO_ CS case.
--
With Best Regards,
Andy Shevchenko
prev parent reply other threads:[~2021-05-06 12:17 UTC|newest]
Thread overview: 10+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-05-06 3:00 [PATCH 0/2] spi: Correct CS GPIOs polarity when using GPIO descriptors Jay Fang
2021-05-06 3:00 ` [PATCH 1/2] " Jay Fang
2021-05-06 3:00 ` [PATCH 2/2] Revert "gpio: of: Handle SPI chipselect legacy bindings" Jay Fang
[not found] ` <CAHp75Vfr8t9UVqVn6hLSN6Mi3=iNAn612eE-qKq9HfrwNhpg3Q@mail.gmail.com>
[not found] ` <CAHp75Vei0QGaKiq5Nai7Gsa=jcMSipaXV_6qZbBy=f0OrN=DHQ@mail.gmail.com>
2021-05-06 9:11 ` [PATCH 0/2] spi: Correct CS GPIOs polarity when using GPIO descriptors Jay Fang
2021-05-06 9:44 ` Andy Shevchenko
2021-05-06 9:51 ` Andy Shevchenko
2021-05-06 11:06 ` Linus Walleij
2021-05-06 11:24 ` Mark Brown
[not found] ` <CAHp75Veoqnd3Hgzq8DAz-_=QxMt-+r608dkzPp67YA5eitLJNw@mail.gmail.com>
2021-05-06 11:34 ` Mark Brown
2021-05-06 12:17 ` Andy Shevchenko [this message]
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