Messages in this thread | | | Subject | Re: [PATCH] phy: lantiq: rcu-usb2: wait after clock enable | From | Hauke Mehrtens <> | Date | Fri, 8 Jan 2021 00:12:51 +0100 |
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On 1/7/21 11:49 PM, Mathias Kresin wrote: > 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. > > Cc: <stable@vger.kernel.org> # v5.7+ > Signed-off-by: Mathias Kresin <dev@kresin.me>
Acked-by: Hauke Mehrtens <hauke@hauke-m.de>
I do not know how long you have to wait here, but this looks ok, when it works.
Hauke
> --- > drivers/phy/lantiq/phy-lantiq-rcu-usb2.c | 10 +++++++++- > 1 file changed, 9 insertions(+), 1 deletion(-) > > diff --git a/drivers/phy/lantiq/phy-lantiq-rcu-usb2.c b/drivers/phy/lantiq/phy-lantiq-rcu-usb2.c > index a7d126192cf1..29d246ea24b4 100644 > --- 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(struct phy *phy) > 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; > } >
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