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authorDaniel Mack <zonque@gmail.com>2014-04-16 17:11:16 +0200
committerFelipe Balbi <balbi@ti.com>2014-04-21 10:21:24 -0500
commita31a942a148e0083ce560ffeb54fb60e06ab7201 (patch)
tree61b9882c9d76d86f19f9bf3c7fd9d7206cef0e0b /drivers/usb
parent2656c9e28125e96bee212f146cc3f2419fd3ffef (diff)
usb: phy: am335x-control: wait 1ms after power-up transitions
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>
Diffstat (limited to 'drivers/usb')
-rw-r--r--drivers/usb/phy/phy-am335x-control.c9
1 files changed, 9 insertions, 0 deletions
diff --git a/drivers/usb/phy/phy-am335x-control.c b/drivers/usb/phy/phy-am335x-control.c
index d75196ad5f2f..35b6083b7999 100644
--- a/drivers/usb/phy/phy-am335x-control.c
+++ b/drivers/usb/phy/phy-am335x-control.c
@@ -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 = {