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    Subject[PATCH 5.12 607/700] usb: dwc2: Dont reset the core after setting turnaround time
    Date
    From: Clément Lassieur <clement@lassieur.org>

    [ Upstream commit aafe93516b8567ab5864e1f4cd3eeabc54fb0e5a ]

    Every time the hub signals a reset while we (device) are hsotg->connected,
    dwc2_hsotg_core_init_disconnected() is called, which in turn calls
    dwc2_hs_phy_init().

    GUSBCFG.USBTrdTim is cleared upon Core Soft Reset, so if
    hsotg->params.phy_utmi_width is 8-bit, the value of GUSBCFG.USBTrdTim (the
    default one: 0x5, corresponding to 16-bit) is always different from
    hsotg->params.phy_utmi_width, thus dwc2_core_reset() is called every
    time (usbcfg != usbcfg_old), which causes 2 issues:

    1) The call to dwc2_core_reset() does another reset 300us after the initial
    Chirp K of the first reset (which should last at least Tuch = 1ms), and
    messes up the High-speed Detection Handshake: both hub and device drive
    current into the D+ and D- lines at the same time.

    2) GUSBCFG.USBTrdTim is cleared by the second reset, so its value is always
    the default one (0x5).

    Setting GUSBCFG.USBTrdTim after the potential call to dwc2_core_reset()
    fixes both issues. It is now set even when select_phy is false because the
    cost of the Core Soft Reset is removed.

    Fixes: 1e868545f2bb ("usb: dwc2: gadget: Move gadget phy init into core phy init")
    Signed-off-by: Clément Lassieur <clement@lassieur.org>
    Link: https://lore.kernel.org/r/20210603155921.940651-1-clement@lassieur.org
    Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
    Signed-off-by: Sasha Levin <sashal@kernel.org>
    ---
    drivers/usb/dwc2/core.c | 30 +++++++++++++++++++++---------
    1 file changed, 21 insertions(+), 9 deletions(-)

    diff --git a/drivers/usb/dwc2/core.c b/drivers/usb/dwc2/core.c
    index fec17a2d2447..15911ac7582b 100644
    --- a/drivers/usb/dwc2/core.c
    +++ b/drivers/usb/dwc2/core.c
    @@ -1167,15 +1167,6 @@ static int dwc2_hs_phy_init(struct dwc2_hsotg *hsotg, bool select_phy)
    usbcfg &= ~(GUSBCFG_ULPI_UTMI_SEL | GUSBCFG_PHYIF16);
    if (hsotg->params.phy_utmi_width == 16)
    usbcfg |= GUSBCFG_PHYIF16;
    -
    - /* Set turnaround time */
    - if (dwc2_is_device_mode(hsotg)) {
    - usbcfg &= ~GUSBCFG_USBTRDTIM_MASK;
    - if (hsotg->params.phy_utmi_width == 16)
    - usbcfg |= 5 << GUSBCFG_USBTRDTIM_SHIFT;
    - else
    - usbcfg |= 9 << GUSBCFG_USBTRDTIM_SHIFT;
    - }
    break;
    default:
    dev_err(hsotg->dev, "FS PHY selected at HS!\n");
    @@ -1197,6 +1188,24 @@ static int dwc2_hs_phy_init(struct dwc2_hsotg *hsotg, bool select_phy)
    return retval;
    }

    +static void dwc2_set_turnaround_time(struct dwc2_hsotg *hsotg)
    +{
    + u32 usbcfg;
    +
    + if (hsotg->params.phy_type != DWC2_PHY_TYPE_PARAM_UTMI)
    + return;
    +
    + usbcfg = dwc2_readl(hsotg, GUSBCFG);
    +
    + usbcfg &= ~GUSBCFG_USBTRDTIM_MASK;
    + if (hsotg->params.phy_utmi_width == 16)
    + usbcfg |= 5 << GUSBCFG_USBTRDTIM_SHIFT;
    + else
    + usbcfg |= 9 << GUSBCFG_USBTRDTIM_SHIFT;
    +
    + dwc2_writel(hsotg, usbcfg, GUSBCFG);
    +}
    +
    int dwc2_phy_init(struct dwc2_hsotg *hsotg, bool select_phy)
    {
    u32 usbcfg;
    @@ -1214,6 +1223,9 @@ int dwc2_phy_init(struct dwc2_hsotg *hsotg, bool select_phy)
    retval = dwc2_hs_phy_init(hsotg, select_phy);
    if (retval)
    return retval;
    +
    + if (dwc2_is_device_mode(hsotg))
    + dwc2_set_turnaround_time(hsotg);
    }

    if (hsotg->hw_params.hs_phy_type == GHWCFG2_HS_PHY_TYPE_ULPI &&
    --
    2.30.2


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