linux-kernel - Re: [PATCH v6 12/17] phy: sun4i-usb: Introduce port2 SIDDQ quirk

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Date:   Mon, 24 May 2021 13:59:46 +0200
From:   Maxime Ripard <maxime@...no.tech>
To:     Andre Przywara <andre.przywara@....com>
Cc:     Chen-Yu Tsai <wens@...e.org>,
        Jernej Skrabec <jernej.skrabec@...il.com>,
        Rob Herring <robh@...nel.org>, Icenowy Zheng <icenowy@...c.io>,
        Samuel Holland <samuel@...lland.org>,
        Ondrej Jirman <megous@...ous.com>,
        linux-arm-kernel@...ts.infradead.org, linux-sunxi@...glegroups.com,
        linux-sunxi@...ts.linux.dev, linux-kernel@...r.kernel.org,
        Kishon Vijay Abraham I <kishon@...com>,
        Vinod Koul <vkoul@...nel.org>, linux-phy@...ts.infradead.org,
        linux-usb@...r.kernel.org
Subject: Re: [PATCH v6 12/17] phy: sun4i-usb: Introduce port2 SIDDQ quirk

Hi

On Wed, May 19, 2021 at 11:41:47AM +0100, Andre Przywara wrote:
> At least the Allwinner H616 SoC requires a weird quirk to make most
> USB PHYs work: Only port2 works out of the box, but all other ports
> need some help from this port2 to work correctly: The CLK_BUS_PHY2 and
> RST_USB_PHY2 clock and reset need to be enabled, and the SIDDQ bit in
> the PMU PHY control register needs to be cleared. For this register to
> be accessible, CLK_BUS_ECHI2 needs to be ungated. Don't ask ....
> 
> Instead of disguising this as some generic feature, do exactly that
> in our PHY init:
> If the quirk bit is set, and we initialise a PHY other than PHY2, ungate
> this one special clock, and clear the SIDDQ bit. We can pull in the
> other required clocks via the DT.
> 
> Signed-off-by: Andre Przywara <andre.przywara@....com>

What is this SIDDQ bit doing exactly?

I guess we could also expose this using a power-domain if it's relevant?

Maxime

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