linux-kernel - Re: [PATCH] arm64: dts: meson: odroid-n2: keep SD card regulator always on

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Message-ID: <7htvb9smvz.fsf@baylibre.com>
Date:   Thu, 25 Jul 2019 16:41:20 -0700
From:   Kevin Hilman <khilman@...libre.com>
To:     Xavier Ruppen <xruppen@...il.com>
Cc:     linux-amlogic@...ts.infradead.org, linux-kernel@...r.kernel.org,
        linux-arm-kernel@...ts.infradead.org, narmstrong@...libre.com,
        martin.blumenstingl@...glemail.com,
        Xavier Ruppen <xruppen@...il.com>
Subject: Re: [PATCH] arm64: dts: meson: odroid-n2: keep SD card regulator always on

Xavier Ruppen <xruppen@...il.com> writes:

> When powering off the Odroid N2, the tflash_vdd regulator is
> automatically turned off by the kernel. This is a problem
> when issuing the "reboot" command while using an SD card.
> The boot ROM does not power this regulator back on, blocking
> the reboot process at the boot ROM stage, preventing the
> SD card from being detected.
>
> Adding the "regulator-always-on" property fixes the problem.
>
> Signed-off-by: Xavier Ruppen <xruppen@...il.com>

Thanks for the fix and the detailed background description.

Queued as a fix for v5.3.

Note that I also added this to the commit log, for the benefit of anyone
wanting to backport.

Fixes: c35f6dc5c377 ("arm64: dts: meson: Add minimal support for Odroid-N2")

>
> Here is what the boot ROM output looks like without this patch:
>
>     [root@...rm ~]# reboot 
>     [...]
>     [   24.275860] shutdown[1]: All loop devices detached.
>     [   24.278864] shutdown[1]: Detaching DM devices.
>     [   24.287105] kvm: exiting hardware virtualization
>     [   24.318776] reboot: Restarting system
>     bl31 reboot reason: 0xd
>     bl31 reboot reason: 0x0
>     system cmd  1.
>     G12B:BL:6e7c85:7898ac;FEAT:E0F83180:2000;POC:F;RCY:0;
>     EMMC:800;NAND:81;SD?:0;SD:400;USB:8;LOOP:1;EMMC:800;
>     NAND:81;SD?:0;SD:400;USB:8;LOOP:2;EMMC:800;NAND:81;
>     SD?:0;SD:400;USB:8;LOOP:3; [...]
>
> Other people can be seen having this problem on the odroid
> forum [1].
>
> The cause of the problem was found by Martin Blumenstingl
> on #linux-amlogic. We may want to add his Suggested-by tag
> if he agrees.

Added.

Thanks!

Kevin