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Subject[PATCH 3/4] usb: phy: omap-usb3: Decrease the number of transitions to recovery
Date
Power-cycling the PHY (partially) decreases the number of transitions to
"Recovery" state. Hence changed the power up sequence to a partial
power-up before a full power-up of the PHY.

Signed-off-by: Kishon Vijay Abraham I <kishon@ti.com>
Signed-off-by: Moiz Sonasath <m-sonasath@ti.com>
---
drivers/usb/phy/omap-usb3.c | 43 ++++++++++++++++++++++++++++++++++++------
include/linux/usb/omap_usb.h | 1 +
2 files changed, 38 insertions(+), 6 deletions(-)

diff --git a/drivers/usb/phy/omap-usb3.c b/drivers/usb/phy/omap-usb3.c
index 26402d5..fb3c5e6 100644
--- a/drivers/usb/phy/omap-usb3.c
+++ b/drivers/usb/phy/omap-usb3.c
@@ -35,13 +35,15 @@ static struct usb_dpll_params omap_usb3_dpll_params[NUM_SYS_CLKS] = {
};

/**
- * omap5_usb_phy_power - power on/off the serializer using control module
+ * omap5_usb_phy_partial_powerup - power on the serializer using control module
* @phy: struct omap_usb *
- * @on: 0 to off and 1 to on based on powering on or off the PHY
*
- * omap_usb3 can call this API to power on or off the PHY.
+ * After the dwc3 module is disabled and enabled again the synchronization
+ * between dwc3 and phy goes bad and the device does not get enumerated
+ * in superspeed mode. After some trials it was found powering up TX and
+ * part of RX PHY helped to solve the issue.
*/
-static int omap5_usb_phy_power(struct omap_usb *phy, bool on)
+static int omap5_usb_phy_partial_powerup(struct omap_usb *phy)
{
u32 val;
unsigned long rate;
@@ -58,10 +60,32 @@ static int omap5_usb_phy_power(struct omap_usb *phy, bool on)

val = readl(phy->control_dev);

+ val &= ~(USB_PWRCTL_CLK_CMD_MASK | USB_PWRCTL_CLK_FREQ_MASK);
+ val |= (USB3_PHY_PARTIAL_RX_POWERON | USB3_PHY_TX_RX_POWERON)
+ << USB_PWRCTL_CLK_CMD_SHIFT;
+ val |= rate << USB_PWRCTL_CLK_FREQ_SHIFT;
+
+ writel(val, phy->control_dev);
+
+ return 0;
+}
+
+/**
+ * omap5_usb_phy_power - power on/off the serializer using control module
+ * @phy: struct omap_usb *
+ * @on: 0 to off and 1 to on based on powering on or off the PHY
+ *
+ * omap_usb3 can call this API to power on or off the PHY.
+ */
+static int omap5_usb_phy_power(struct omap_usb *phy, bool on)
+{
+ u32 val;
+
+ val = readl(phy->control_dev);
+
if (on) {
- val &= ~(USB_PWRCTL_CLK_CMD_MASK | USB_PWRCTL_CLK_FREQ_MASK);
+ val &= ~USB_PWRCTL_CLK_CMD_MASK;
val |= USB3_PHY_TX_RX_POWERON << USB_PWRCTL_CLK_CMD_SHIFT;
- val |= rate << USB_PWRCTL_CLK_FREQ_SHIFT;
} else {
val &= ~USB_PWRCTL_CLK_CMD_MASK;
val |= USB3_PHY_TX_RX_POWEROFF << USB_PWRCTL_CLK_CMD_SHIFT;
@@ -207,6 +231,13 @@ static int omap_usb3_init(struct usb_phy *x)
struct omap_usb *phy = phy_to_omapusb(x);

omap_usb_dpll_lock(phy);
+ omap5_usb_phy_partial_powerup(phy);
+ /*
+ * Give enough time for the PHY to partially power-up before
+ * powering it up completely. delay value suggested by the HW
+ * team.
+ */
+ mdelay(100);
omap5_usb_phy_power(phy, 1);

return 0;
diff --git a/include/linux/usb/omap_usb.h b/include/linux/usb/omap_usb.h
index 01ed008..62b637c 100644
--- a/include/linux/usb/omap_usb.h
+++ b/include/linux/usb/omap_usb.h
@@ -92,6 +92,7 @@ struct omap_usb {

#define USB3_PHY_TX_RX_POWERON 0x3
#define USB3_PHY_TX_RX_POWEROFF 0x0
+#define USB3_PHY_PARTIAL_RX_POWERON (0x1 << 6)

#define phy_to_omapusb(x) container_of((x), struct omap_usb, phy)

--
1.7.9.5


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