linux-kernel - [PATCH v4 2/2] phy: rockchip-inno-usb2: correct 480MHz output clock stable time

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Message-Id: <1479182047-3399-3-git-send-email-wulf@rock-chips.com>
Date:   Tue, 15 Nov 2016 11:54:07 +0800
From:   William Wu <wulf@...k-chips.com>
To:     kishon@...com, heiko@...ech.de
Cc:     linux-kernel@...r.kernel.org, linux-arm-kernel@...ts.infradead.org,
        linux-rockchip@...ts.infradead.org, devicetree@...r.kernel.org,
        robh+dt@...nel.org, frank.wang@...k-chips.com,
        huangtao@...k-chips.com, dianders@...gle.com,
        briannorris@...gle.com, groeck@...gle.com, wulf@...k-chips.com
Subject: [PATCH v4 2/2] phy: rockchip-inno-usb2: correct 480MHz output clock stable time

We found that the system crashed due to 480MHz output clock of
USB2 PHY was unstable after clock had been enabled by gpu module.

Theoretically, 1 millisecond is a critical value for 480MHz
output clock stable time, so we try to change the delay time
to 1.2 millisecond to avoid this issue.

And the commit ed907fb1d7c3 ("phy: rockchip-inno-usb2: correct
clk_ops callback") used prepare callbacks instead of enable
callbacks to support gate a clk if the operation may sleep. So
we can switch from delay to sleep functions.

Also fix a spelling error from "waitting" to "waiting".

Signed-off-by: William Wu <wulf@...k-chips.com>
Reviewed-by: Douglas Anderson <dianders@...omium.org>
---
Changes in v4:
- add Reviewed-by and fix a spelling error

Changes in v3:
- None

Changes in v2:
- None

 drivers/phy/phy-rockchip-inno-usb2.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/drivers/phy/phy-rockchip-inno-usb2.c b/drivers/phy/phy-rockchip-inno-usb2.c
index 365e077..5d922fc 100644
--- a/drivers/phy/phy-rockchip-inno-usb2.c
+++ b/drivers/phy/phy-rockchip-inno-usb2.c
@@ -165,8 +165,8 @@ static int rockchip_usb2phy_clk480m_prepare(struct clk_hw *hw)
 		if (ret)
 			return ret;
 
-		/* waitting for the clk become stable */
-		mdelay(1);
+		/* waiting for the clk become stable */
+		usleep_range(1200, 1300);
 	}
 
 	return 0;
-- 
2.0.0