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Date:   Mon, 17 Apr 2023 14:57:07 +0300
From:   Dmitry Rokosov <ddrokosov@sberdevices.ru>
To:     Martin Blumenstingl <martin.blumenstingl@googlemail.com>
CC:     <gregkh@linuxfoundation.org>, <robh+dt@kernel.org>,
        <krzysztof.kozlowski+dt@linaro.org>, <neil.armstrong@linaro.org>,
        <khilman@baylibre.com>, <jbrunet@baylibre.com>,
        <mturquette@baylibre.com>, <vkoul@kernel.org>, <kishon@kernel.org>,
        <hminas@synopsys.com>, <Thinh.Nguyen@synopsys.com>,
        <yue.wang@amlogic.com>, <hanjie.lin@amlogic.com>,
        <kernel@sberdevices.ru>, <rockosov@gmail.com>,
        <linux-usb@vger.kernel.org>, <devicetree@vger.kernel.org>,
        <linux-kernel@vger.kernel.org>,
        <linux-arm-kernel@lists.infradead.org>,
        <linux-amlogic@lists.infradead.org>,
        <linux-phy@lists.infradead.org>
Subject: Re: [PATCH v1 1/5] phy: amlogic: during USB PHY clkin obtaining,
 enable it
Message-ID: <20230417115707.p5btzzg4rlyzf7ni@CAB-WSD-L081021>
References: <20230414152423.19842-1-ddrokosov@sberdevices.ru>
 <20230414152423.19842-2-ddrokosov@sberdevices.ru>
 <CAFBinCCEhobbyKHuKDWzTYCQWgNT1-e8=7hMhq1mvT6CuEOjGw@mail.gmail.com>
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On Sun, Apr 16, 2023 at 10:54:17PM +0200, Martin Blumenstingl wrote:
> Hi Dmitry,
> 
> On Fri, Apr 14, 2023 at 5:24 PM Dmitry Rokosov <ddrokosov@sberdevices.ru> wrote:
> [...]
> > -       priv->clk = devm_clk_get(dev, "xtal");
> > +       priv->clk = devm_clk_get_enabled(dev, "xtal");
> Generally this works fine but I wouldn't recommend this approach if:
> - there's some required wait time after the clock has been enabled
> (see phy_meson_g12a_usb2_init - there's already some required wait
> time after triggering the reset)
> - clock gating (for power saving) is needed when the dwc3 driver is
> unloaded by the PHY driver is not
> 
> In this case: just manually manage the clock in phy_meson_g12a_usb2_{init,exit}

I'm sorry, but I'm not fully understanding your point. Currently, no
sleeps are required for this clock and we don't have any logic for
power saving (g12a phy_ops doesn't have power_on()/power_off()
implementation).
However, I believe all of your arguments make sense for the future
development of the phy_meson_g12a_usb2 driver. Is that correct?

-- 
Thank you,
Dmitry