This is a note to let you know that I've just added the patch titled phy: lantiq: rcu-usb2: wait after clock enable to the 5.10-stable tree which can be found at: http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary The filename of the patch is: phy-lantiq-rcu-usb2-wait-after-clock-enable.patch and it can be found in the queue-5.10 subdirectory. If you, or anyone else, feels it should not be added to the stable tree, please let <stable@xxxxxxxxxxxxxxx> know about it. >From 36acd5e24e3000691fb8d1ee31cf959cb1582d35 Mon Sep 17 00:00:00 2001 From: Mathias Kresin <dev@xxxxxxxxx> Date: Thu, 7 Jan 2021 23:49:01 +0100 Subject: phy: lantiq: rcu-usb2: wait after clock enable From: Mathias Kresin <dev@xxxxxxxxx> commit 36acd5e24e3000691fb8d1ee31cf959cb1582d35 upstream. Commit 65dc2e725286 ("usb: dwc2: Update Core Reset programming flow.") revealed that the phy isn't ready immediately after enabling it's clocks. The dwc2_check_core_version() fails and the dwc2 usb driver errors out. Add a short delay to let the phy get up and running. There isn't any documentation how much time is required, the value was chosen based on tests. Signed-off-by: Mathias Kresin <dev@xxxxxxxxx> Acked-by: Hauke Mehrtens <hauke@xxxxxxxxxx> Acked-by: Martin Blumenstingl <martin.blumenstingl@xxxxxxxxxxxxxx> Cc: <stable@xxxxxxxxxxxxxxx> # v5.7+ Link: https://lore.kernel.org/r/20210107224901.2102479-1-dev@xxxxxxxxx Signed-off-by: Vinod Koul <vkoul@xxxxxxxxxx> Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx> --- drivers/phy/lantiq/phy-lantiq-rcu-usb2.c | 10 +++++++++- 1 file changed, 9 insertions(+), 1 deletion(-) --- a/drivers/phy/lantiq/phy-lantiq-rcu-usb2.c +++ b/drivers/phy/lantiq/phy-lantiq-rcu-usb2.c @@ -124,8 +124,16 @@ static int ltq_rcu_usb2_phy_power_on(str reset_control_deassert(priv->phy_reset); ret = clk_prepare_enable(priv->phy_gate_clk); - if (ret) + if (ret) { dev_err(dev, "failed to enable PHY gate\n"); + return ret; + } + + /* + * at least the xrx200 usb2 phy requires some extra time to be + * operational after enabling the clock + */ + usleep_range(100, 200); return ret; } Patches currently in stable-queue which might be from dev@xxxxxxxxx are queue-5.10/phy-lantiq-rcu-usb2-wait-after-clock-enable.patch