linux-kernel - Re: [PATCH 2/6] pinctrl: sunxi: Add I/O bias setting for H6 R-PIO

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Message-ID: <bfb768a8-8286-c596-8b10-28222c962ec3@sholland.org>
Date:   Mon, 27 Jun 2022 22:18:48 -0500
From:   Samuel Holland <samuel@...lland.org>
To:     Jernej Škrabec <jernej.skrabec@...il.com>,
        Chen-Yu Tsai <wens@...e.org>,
        Linus Walleij <linus.walleij@...aro.org>
Cc:     Krzysztof Kozlowski <krzysztof.kozlowski+dt@...aro.org>,
        Maxime Ripard <mripard@...nel.org>, Ondrej Jirman <x@....cz>,
        Rob Herring <robh+dt@...nel.org>, devicetree@...r.kernel.org,
        linux-arm-kernel@...ts.infradead.org, linux-gpio@...r.kernel.org,
        linux-kernel@...r.kernel.org, linux-sunxi@...ts.linux.dev
Subject: Re: [PATCH 2/6] pinctrl: sunxi: Add I/O bias setting for H6 R-PIO

On 6/27/22 3:34 PM, Jernej Škrabec wrote:
> Dne nedelja, 26. junij 2022 ob 04:11:43 CEST je Samuel Holland napisal(a):
>> H6 requires I/O bias configuration on both of its PIO devices.
>> Previously it was only done for the main PIO.
>>
>> The setting for Port L is at bit 0, so the bank calculation needs to
>> account for the pin base. Otherwise the wrong bit is used.
>>
>> Fixes: cc62383fcebe ("pinctrl: sunxi: Support I/O bias voltage setting on
>> H6") Signed-off-by: Samuel Holland <samuel@...lland.org>
> 
> Reviewed-by: Jernej Skrabec <jernej.skrabec@...il.com>
> 
> Did you noticed any improvement with this properly set? In theory, 3.3 V bias 
> should always work, right?

I think it matters for inputs, which may not detect a high level state if the
bias (comparator reference) voltage is too high.

It looks like Orange Pi 3 has a 1.8 V supply for port M. I am not currently set
up to test the behavior with different bias settings, but I may do that if I get
the chance.

Regards,
Samuel