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From:   Kevin Hilman <khilman@baylibre.com>
To:     "shunzhou.jiang@amlogic.com" <shunzhou.jiang@amlogic.com>,
        linux-arm-kernel <linux-arm-kernel@lists.infradead.org>,
        linux-amlogic <linux-amlogic@lists.infradead.org>,
        linux-kernel <linux-kernel@vger.kernel.org>
Cc:     Neil Armstrong <narmstrong@baylibre.com>,
        jbrunet <jbrunet@baylibre.com>,
        Martin Blumenstingl <martin.blumenstingl@googlemail.com>,
        "jianxin.pan" <jianxin.pan@amlogic.com>
Subject: Re: Re: [PATCH 2/2] soc: s4: Add support for power domains controller
In-Reply-To: <202202091001287547451@amlogic.com>
References: <20220126061018.705338-1-shunzhou.jiang@amlogic.com>
 <20220126061018.705338-3-shunzhou.jiang@amlogic.com>
 <7hzgnal5yu.fsf@baylibre.com> <202202091001287547451@amlogic.com>
Date:   Wed, 09 Feb 2022 12:30:55 -0800
Message-ID: <7hee4bok8w.fsf@baylibre.com>
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"shunzhou.jiang@amlogic.com" <shunzhou.jiang@amlogic.com> writes:

> Hi  Kevin:
> Thanks your reply.
> Please refer to below comment,
>> S4_VPU_HDMI:  for vpu domain,  this domain provide power to many moudles(osd, vpp, hdr, dv, di), if close, will cause system crash
>> S4_USB_COMB domain: for usb, if not always on,  all usb status will clear to 0, that's not right status for usb

Yes, I understand, this is teh same as for other SoCs (e.g. A1.)   The
solution is not to set the domain to always on.  The solution is for the
drivers for the devices in these domains use runtime PM so that when the
drivers are active, the power domain does not get shut off.

>> S4_ETH: for ethernet online wakeup, and if power down, status also not right

OK, this one makes sense for "always on" since it used by firmware for
wakeup.

Kevin