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phy: lantiq: rcu-usb2: wait after clock enable 

Commit 65dc2e7252 ("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@kresin.me>
Acked-by: Hauke Mehrtens <hauke@hauke-m.de>
Acked-by: Martin Blumenstingl <martin.blumenstingl@googlemail.com>
Cc: <stable@vger.kernel.org> # v5.7+
Link: https://lore.kernel.org/r/20210107224901.2102479-1-dev@kresin.me
Signed-off-by: Vinod Koul <vkoul@kernel.org>
This commit is contained in:
Mathias Kresin 2021-01-07 23:49:01 +01:00 committed by Vinod Koul
parent c188365402
commit 36acd5e24e
1 changed files with 9 additions and 1 deletions
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10
drivers/phy/lantiq/phy-lantiq-rcu-usb2.c
View File

@ -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;
}