From: Andrew Jeffery <andrew@codeconstruct.com.au>
To: Nikita Shubin <nikita.shubin@maquefel.me>, Joel Stanley <joel@jms.id.au>
Cc: linux-gpio@vger.kernel.org
Subject: Re: Question about ASPEED GPIO value/direction set order
Date: Thu, 13 Mar 2025 16:51:49 +1030 [thread overview]
Message-ID: <4878ed9cfd9ff20550cf0d9d8933ec993f4b288c.camel@codeconstruct.com.au> (raw)
In-Reply-To: <3cd0fe0ff42a751fd0738dacf16badcaa8ff51fb.camel@maquefel.me>
Hi Nikita,
On Tue, 2025-03-11 at 15:40 +0300, Nikita Shubin wrote:
> Hi Joel and Andrew !
>
> I am observing "strange" behaviour when pin direction is set AFTER
> the
> value itself:
>
> ```
> aspeed_gpio_dir_out:
>
> __aspeed_gpio_set(gc, offset, val);
> gpio->config->llops->reg_bit_set(gpio, offset, reg_dir, 1);
> ```
>
> Is this as intended ?
Yes; you tend to set the value only when using the GPIO for output, and
by setting the value before setting the direction, we avoid the
potential value glitch which occurs under the opposite order.
Andrew
next prev parent reply other threads:[~2025-03-13 6:22 UTC|newest]
Thread overview: 4+ messages / expand[flat|nested] mbox.gz Atom feed top
2025-03-11 12:40 Question about ASPEED GPIO value/direction set order Nikita Shubin
2025-03-13 6:21 ` Andrew Jeffery [this message]
2025-03-13 7:39 ` Nikita Shubin
2025-03-18 0:48 ` Andrew Jeffery
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