usb: ehci-omap: Don't softreset USB High-speed Host (UHH) Module
Fixes NFS root problems with Beagle (3530 ES1.0) when used with
external USB-ethernet adapter and "USB start" command used within
u-boot.
Soft resetting the UHH module causes instability issues on
all OMAPs so we just avoid it.
See OMAP36xx Errata
i571: USB host EHCI may stall when entering smart-standby mode
i660: USBHOST Configured In Smart-Idle Can Lead To a Deadlock
On OMAP4/5, soft-resetting the UHH module can put it into
Smart-Idle mode and lead to a deadlock.
On OMAP3 this doesn't seem to be the case but still instabilities
are observed on beagle (3530 ES1.0) if soft-reset is used.
e.g. NFS root failures with Linux kernel.
Signed-off-by: Roger Quadros <rogerq@ti.com>
diff --git a/drivers/usb/host/ehci-omap.c b/drivers/usb/host/ehci-omap.c
index a47e078..032d5e5 100644
--- a/drivers/usb/host/ehci-omap.c
+++ b/drivers/usb/host/ehci-omap.c
@@ -28,18 +28,21 @@
static int omap_uhh_reset(void)
{
- unsigned long init = get_timer(0);
-
- /* perform UHH soft reset, and wait until reset is complete */
- writel(OMAP_UHH_SYSCONFIG_SOFTRESET, &uhh->sysc);
-
- /* Wait for UHH reset to complete */
- while (!(readl(&uhh->syss) & OMAP_UHH_SYSSTATUS_EHCI_RESETDONE))
- if (get_timer(init) > CONFIG_SYS_HZ) {
- debug("OMAP UHH error: timeout resetting ehci\n");
- return -EL3RST;
- }
-
+/*
+ * Soft resetting the UHH module causes instability issues on
+ * all OMAPs so we just avoid it.
+ *
+ * See OMAP36xx Errata
+ * i571: USB host EHCI may stall when entering smart-standby mode
+ * i660: USBHOST Configured In Smart-Idle Can Lead To a Deadlock
+ *
+ * On OMAP4/5, soft-resetting the UHH module will put it into
+ * Smart-Idle mode and lead to a deadlock.
+ *
+ * On OMAP3, this doesn't seem to be the case but still instabilities
+ * are observed on beagle (3530 ES1.0) if soft-reset is used.
+ * e.g. NFS root failures with Linux kernel.
+ */
return 0;
}