linux-kernel - Re: [PATCH v2 6/8] phy: amlogic: Add Amlogic G12A USB3 + PCIE Combo PHY Driver

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Date:   Mon, 11 Mar 2019 22:14:27 +0100
From:   Martin Blumenstingl <martin.blumenstingl@...glemail.com>
To:     Neil Armstrong <narmstrong@...libre.com>
Cc:     gregkh@...uxfoundation.org, hminas@...opsys.com, balbi@...nel.org,
        kishon@...com, linux-amlogic@...ts.infradead.org,
        linux-usb@...r.kernel.org, linux-kernel@...r.kernel.org,
        linux-arm-kernel@...ts.infradead.org
Subject: Re: [PATCH v2 6/8] phy: amlogic: Add Amlogic G12A USB3 + PCIE Combo
 PHY Driver

Hi Neil,

On Thu, Mar 7, 2019 at 9:44 AM Neil Armstrong <narmstrong@...libre.com> wrote:
>
> On 06/03/2019 22:04, Martin Blumenstingl wrote:
> > Hi Neil,
> >
> > On Mon, Mar 4, 2019 at 11:40 AM Neil Armstrong <narmstrong@...libre.com> wrote:
> > [...]
> >> +static int phy_g12a_usb3_init(struct phy *phy)
> >> +{
> >> +       struct phy_g12a_usb3_pcie_priv *priv = phy_get_drvdata(phy);
> >> +       int data, ret;
> >> +
> >> +       /* Switch PHY to USB3 */
> >> +       regmap_update_bits(priv->regmap, PHY_R0,
> >> +                          PHY_R0_PCIE_USB3_SWITCH,
> >> +                          PHY_R0_PCIE_USB3_SWITCH);
> > does this automatically clear PHY_R0_PCIE_POWER_STATE (in case the
> > bootloader incorrectly set that)?
>
> Don't forget it's a static configuration, on the board, only USB3 XOR PCIE
> will be available, if the bootloader sets this and the kernel uses USB3,
> or the reverse, one of them is wrong.
I'm specifically asking is because we've seen various GXL/GXM boards
with a bootloader which is configured for the wrong PHY interface
(RGMII != RMII)

> >
> > [...]
> >> +static int phy_g12a_usb3_pcie_init(struct phy *phy)
> >> +{
> >> +       struct phy_g12a_usb3_pcie_priv *priv = phy_get_drvdata(phy);
> >> +       int ret;
> >> +
> >> +       ret = reset_control_reset(priv->reset);
> >> +       if (ret)
> >> +               return ret;
> >> +
> >> +       if (priv->mode == PHY_TYPE_USB3)
> >> +               return phy_g12a_usb3_init(phy);
> >> +
> >> +       /* Power UP PCIE */
> >> +       regmap_update_bits(priv->regmap, PHY_R0,
> >> +                          PHY_R0_PCIE_POWER_STATE,
> >> +                          FIELD_PREP(PHY_R0_PCIE_POWER_STATE, 0x1c));
> > similar to my question above: does this automatically clear
> > PHY_R0_PCIE_USB3_SWITCH (in case the bootloader incorrectly set that)?
>
> Same answer, but I'll investigate to have more details on this register.
>
> It's more an implementation issue, we can change it when PCIe is enabled
> on this platform.
I'm fine with postponing this until we bring up PCIe support on this
platform if you add a comment (preferably marked with "TODO") in the
driver. that makes it obvious to everyone who comes across this in the
PHY driver

with a TODO-comment you can add my:
Reviewed-by: Martin Blumenstingl <martin.blumenstingl@...glemail.com>


Regards
Martin