On 21-06-13 17:59:35, Dmitry Osipenko wrote:
> Some devices need an extra delay after losing VBUS, otherwise VBUS may
> be detected as active at suspend time, preventing the PHY's suspension
> by the VBUS detection sensor. This problem was found on Asus Transformer
> TF700T (Tegra30) tablet device, where the USB PHY wakes up immediately
> from suspend because VBUS sensor continues to detect VBUS as active after
> disconnection. We need to poll the PHY's VBUS wakeup status until it's
> deasserted before suspending PHY in order to fix this minor trouble.
>
> Fixes: 35192007d28d ("usb: phy: tegra: Support waking up from a low power mode")
> Reported-by: Maxim Schwalm <maxim.schwalm@xxxxxxxxx> # Asus TF700T
> Tested-by: Maxim Schwalm <maxim.schwalm@xxxxxxxxx> # Asus TF700T
> Signed-off-by: Dmitry Osipenko <digetx@xxxxxxxxx>
> ---
> drivers/usb/phy/phy-tegra-usb.c | 10 ++++++++++
> 1 file changed, 10 insertions(+)
>
> diff --git a/drivers/usb/phy/phy-tegra-usb.c b/drivers/usb/phy/phy-tegra-usb.c
> index fc5c6cab58ba..ff482c694200 100644
> --- a/drivers/usb/phy/phy-tegra-usb.c
> +++ b/drivers/usb/phy/phy-tegra-usb.c
> @@ -64,6 +64,7 @@
> #define A_VBUS_VLD_WAKEUP_EN BIT(30)
>
> #define USB_PHY_VBUS_WAKEUP_ID 0x408
> +#define VBUS_WAKEUP_STS BIT(10)
> #define VBUS_WAKEUP_WAKEUP_EN BIT(30)
>
> #define USB1_LEGACY_CTRL 0x410
> @@ -645,6 +646,15 @@ static int utmi_phy_power_off(struct tegra_usb_phy *phy)
> void __iomem *base = phy->regs;
> u32 val;
>
> + /*
> + * Give hardware time to settle down after VBUS disconnection,
> + * otherwise PHY will immediately wake up from suspend.
> + */
> + if (phy->wakeup_enabled && phy->mode != USB_DR_MODE_HOST)
> + readl_relaxed_poll_timeout(base + USB_PHY_VBUS_WAKEUP_ID,
> + val, !(val & VBUS_WAKEUP_STS),
> + 5000, 100000);
> +
Where will clear VBUS_WAKEUP_STS? Or it will be cleared by HW after VBUS lower than
B Session Valid?
--
Thanks,
Peter Chen
