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    Subject[PATCH 5.9 707/757] usb: ohci: Default to per-port over-current protection
    Date
    From: Hamish Martin <hamish.martin@alliedtelesis.co.nz>

    [ Upstream commit b77d2a0a223bc139ee8904991b2922d215d02636 ]

    Some integrated OHCI controller hubs do not expose all ports of the hub
    to pins on the SoC. In some cases the unconnected ports generate
    spurious over-current events. For example the Broadcom 56060/Ranger 2 SoC
    contains a nominally 3 port hub but only the first port is wired.

    Default behaviour for ohci-platform driver is to use global over-current
    protection mode (AKA "ganged"). This leads to the spurious over-current
    events affecting all ports in the hub.

    We now alter the default to use per-port over-current protection.

    This patch results in the following configuration changes depending
    on quirks:
    - For quirk OHCI_QUIRK_SUPERIO no changes. These systems remain set up
    for ganged power switching and no over-current protection.
    - For quirk OHCI_QUIRK_AMD756 or OHCI_QUIRK_HUB_POWER power switching
    remains at none, while over-current protection is now guaranteed to be
    set to per-port rather than the previous behaviour where it was either
    none or global over-current protection depending on the value at
    function entry.

    Suggested-by: Alan Stern <stern@rowland.harvard.edu>
    Acked-by: Alan Stern <stern@rowland.harvard.edu>
    Signed-off-by: Hamish Martin <hamish.martin@alliedtelesis.co.nz>
    Link: https://lore.kernel.org/r/20200910212512.16670-1-hamish.martin@alliedtelesis.co.nz
    Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
    Signed-off-by: Sasha Levin <sashal@kernel.org>
    ---
    drivers/usb/host/ohci-hcd.c | 16 ++++++++++------
    1 file changed, 10 insertions(+), 6 deletions(-)

    diff --git a/drivers/usb/host/ohci-hcd.c b/drivers/usb/host/ohci-hcd.c
    index dd37e77dae001..2845ea328a064 100644
    --- a/drivers/usb/host/ohci-hcd.c
    +++ b/drivers/usb/host/ohci-hcd.c
    @@ -673,20 +673,24 @@ static int ohci_run (struct ohci_hcd *ohci)

    /* handle root hub init quirks ... */
    val = roothub_a (ohci);
    - val &= ~(RH_A_PSM | RH_A_OCPM);
    + /* Configure for per-port over-current protection by default */
    + val &= ~RH_A_NOCP;
    + val |= RH_A_OCPM;
    if (ohci->flags & OHCI_QUIRK_SUPERIO) {
    - /* NSC 87560 and maybe others */
    + /* NSC 87560 and maybe others.
    + * Ganged power switching, no over-current protection.
    + */
    val |= RH_A_NOCP;
    - val &= ~(RH_A_POTPGT | RH_A_NPS);
    - ohci_writel (ohci, val, &ohci->regs->roothub.a);
    + val &= ~(RH_A_POTPGT | RH_A_NPS | RH_A_PSM | RH_A_OCPM);
    } else if ((ohci->flags & OHCI_QUIRK_AMD756) ||
    (ohci->flags & OHCI_QUIRK_HUB_POWER)) {
    /* hub power always on; required for AMD-756 and some
    - * Mac platforms. ganged overcurrent reporting, if any.
    + * Mac platforms.
    */
    val |= RH_A_NPS;
    - ohci_writel (ohci, val, &ohci->regs->roothub.a);
    }
    + ohci_writel(ohci, val, &ohci->regs->roothub.a);
    +
    ohci_writel (ohci, RH_HS_LPSC, &ohci->regs->roothub.status);
    ohci_writel (ohci, (val & RH_A_NPS) ? 0 : RH_B_PPCM,
    &ohci->regs->roothub.b);
    --
    2.25.1


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