linux-kernel - Re: [PATCH 6/6] arm64: dts: imx8mm-kontron: Add support for reading SD

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Message-ID: <f819ed93-67fc-d052-36af-142c0c09683f@kontron.de>
Date:   Mon, 13 Feb 2023 17:15:44 +0100
From:   Frieder Schrempf <frieder.schrempf@...tron.de>
To:     Marek Vasut <marex@...x.de>, Frieder Schrempf <frieder@...s.de>,
        devicetree@...r.kernel.org,
        Krzysztof Kozlowski <krzysztof.kozlowski+dt@...aro.org>,
        linux-arm-kernel@...ts.infradead.org, linux-kernel@...r.kernel.org,
        Rob Herring <robh+dt@...nel.org>,
        Sascha Hauer <s.hauer@...gutronix.de>,
        Shawn Guo <shawnguo@...nel.org>
Cc:     Fabio Estevam <festevam@...il.com>,
        Heiko Thiery <heiko.thiery@...il.com>,
        Krzysztof Kozlowski <krzysztof.kozlowski@...aro.org>,
        NXP Linux Team <linux-imx@....com>,
        Oleksij Rempel <linux@...pel-privat.de>,
        Pengutronix Kernel Team <kernel@...gutronix.de>
Subject: Re: [PATCH 6/6] arm64: dts: imx8mm-kontron: Add support for reading
 SD_VSEL signal

On 13.02.23 17:08, Marek Vasut wrote:
> On 2/13/23 16:58, Frieder Schrempf wrote:
>> From: Frieder Schrempf <frieder.schrempf@...tron.de>
>>
>> This fixes the LDO5 regulator handling of the pca9450 driver by
>> taking the status of the SD_VSEL into account to determine which
>> configuration register is used for the voltage setting.
>>
>> Even without this change there is no functional issue, as the code
>> for switching the voltage in sdhci.c currently switches both, the
>> VSELECT/SD_VSEL signal and the regulator voltage at the same time
>> and doesn't run into an invalid corner case.
>>
>> We should still make sure, that we always use the correct register
>> when controlling the regulator. At least in U-Boot this fixes an
>> actual bug where the wrong IO voltage is used.
>>
>> Signed-off-by: Frieder Schrempf <frieder.schrempf@...tron.de>
> 
> I may have a kind-of obvious request, since we removed those SD_VSEL
> very recently from other boards, could you just revert all those patches
> and only fill in the SION bit in V2 on all those boards too ? That way,
> we fix the LDO5 regulator for everyone who used it before.

I thought about that, but as the SD_VSEL signal is controlling the LDO5,
I found it more useful/correct to have the sd-vsel-gpios property inside
the LDO5 regulator node. Therefore the old usage where sd-vsel-gpios was
inside the PMIC node isn't compatible anymore.