From: Peter Chen <peter.chen@kernel.org>
To: Dmitry Osipenko <digetx@gmail.com>
Cc: Thierry Reding <thierry.reding@gmail.com>,
Jonathan Hunter <jonathanh@nvidia.com>,
Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
Felipe Balbi <balbi@kernel.org>,
Maxim Schwalm <maxim.schwalm@gmail.com>,
linux-tegra@vger.kernel.org, linux-usb@vger.kernel.org,
linux-kernel@vger.kernel.org
Subject: Re: [PATCH v1 1/2] usb: phy: tegra: Wait for VBUS wakeup status deassertion on suspend
Date: Tue, 15 Jun 2021 09:05:16 +0800 [thread overview]
Message-ID: <20210615010516.GA28352@nchen> (raw)
In-Reply-To: <20210613145936.9902-1-digetx@gmail.com>
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@gmail.com> # Asus TF700T
> Tested-by: Maxim Schwalm <maxim.schwalm@gmail.com> # Asus TF700T
> Signed-off-by: Dmitry Osipenko <digetx@gmail.com>
> ---
> 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
next prev parent reply other threads:[~2021-06-15 3:01 UTC|newest]
Thread overview: 6+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-06-13 14:59 [PATCH v1 1/2] usb: phy: tegra: Wait for VBUS wakeup status deassertion on suspend Dmitry Osipenko
2021-06-13 14:59 ` [PATCH v1 2/2] usb: phy: tegra: Correct definition of B_SESS_VLD_WAKEUP_EN bit Dmitry Osipenko
2021-06-15 1:05 ` Peter Chen [this message]
2021-06-15 14:48 ` [PATCH v1 1/2] usb: phy: tegra: Wait for VBUS wakeup status deassertion on suspend Dmitry Osipenko
2021-06-15 1:06 ` Peter Chen
2021-06-16 0:56 ` Peter Chen
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