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usb: phy: am335x-control: wait 1ms after power-up transitions

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Tests have shown that when a power-up transition is followed by other
PHY operations too quickly, the USB port appears dead. Waiting 1ms fixes
this problem.

Signed-off-by: Daniel Mack <zonque@gmail.com>
Cc: stable@vger.kernel.org [3.14]
Signed-off-by: Felipe Balbi <balbi@ti.com>
This commit is contained in:
Daniel Mack 2014-04-16 17:11:16 +02:00 committed by Felipe Balbi
parent 2656c9e281
commit a31a942a14
1 changed files with 9 additions and 0 deletions
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9
drivers/usb/phy/phy-am335x-control.c
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@ -3,6 +3,7 @@
#include <linux/err.h>
#include <linux/of.h>
#include <linux/io.h>
#include <linux/delay.h>
#include "am35x-phy-control.h"
struct am335x_control_usb {
@ -86,6 +87,14 @@ static void am335x_phy_power(struct phy_control *phy_ctrl, u32 id, bool on)
}
writel(val, usb_ctrl->phy_reg + reg);
/*
* Give the PHY ~1ms to complete the power up operation.
* Tests have shown unstable behaviour if other USB PHY related
* registers are written too shortly after such a transition.
*/
if (on)
mdelay(1);
}
static const struct phy_control ctrl_am335x = {