linux-kernel - Re: [PATCH v2 3/4] ARM: dts: exynos: Add regulator suspend configuration to Odroid XU3/XU4/HC1 family

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Date:   Mon, 24 Jun 2019 09:41:27 +0200
From:   Krzysztof Kozlowski <krzk@...nel.org>
To:     Marek Szyprowski <m.szyprowski@...sung.com>
Cc:     Anand Moon <linux.amoon@...il.com>, Kukjin Kim <kgene@...nel.org>,
        devicetree <devicetree@...r.kernel.org>,
        linux-arm-kernel <linux-arm-kernel@...ts.infradead.org>,
        "linux-samsung-soc@...r.kernel.org" 
        <linux-samsung-soc@...r.kernel.org>,
        Linux Kernel <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH v2 3/4] ARM: dts: exynos: Add regulator suspend
 configuration to Odroid XU3/XU4/HC1 family

On Mon, 24 Jun 2019 at 09:20, Marek Szyprowski <m.szyprowski@...sung.com> wrote:
>
> Hi Anand,
>
> On 2019-06-23 18:02, Anand Moon wrote:
> > Thanks for this patch. Please add my
> >
> > Tested-by: Anand Moon <linux.amoon@...il.com>
> >
> > [snip]
> >
> > Could you integrate below small changes into this patch.
> > with these below changes suspend and resume work correctly at my end.
> >
> > [1] XU4_suspendresume.patch
> >
> > As per S2MPS11B PMIC 1.2.1 Regulator (Features)
> > Fix the min max value for *Buck7* and *Buck8*
> >
> > -- Buck7 (VDD_1.0V_LDO) 1.5 A (1.2 V to 1.5 V, 12.5 mV step, default on 1.35 V)
> > -- Buck8 (VDD_1.8V_LDO) 2.5 A (1.8 V to 2.1 V, 12.5 mV step, default on 2.0 V)
>
> Could you elaborate why such change for Buck7 and Buck8 is needed?

Anand has here valid point - the constraints in DTS do not match
hardware manual. This leads to question whether voltage table in
driver is proper... Another point is the voltage itself. The
schematics describes them as at specific voltage (1.35 V and 2.0 V)
but after boot they are 1.2 V and 1.85 V. Maybe this shift comes from
the problem above.

>
> > Also add suspend-off for *Buck9*
> > Buck9 internally controls the power of USB hub.
> > Adding suspend the this node help proper reset of USB hub on Odroid
> > XU4 / HC1/ XU3
> > during suspend and resume. Below it the logs from my testing.
>
> Disabling Buck9 in suspend indeed reduces the power consumed by the
> board during suspend-to-ram from about 80mA to as little as 7-10mA, what
> matches the results of OdroidXU3. Thanks for the hint!

Although I did not get what is the difference in the logs (Anand
pasted two logs but they look the same) but the power consumption is
reason is good enough. I would be happy to put in the changelog entire
consumption  difference. I can measure it on XU3-Lite but can you give
me the XU4 (before and after)?

Best regards,
Krzysztof