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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>
This commit is contained in:
Roger Quadros 2013-07-22 11:14:37 +03:00 committed by Marek Vasut
parent 6bed7ce569
commit bb1f327d0a
1 changed files with 15 additions and 12 deletions
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27
drivers/usb/host/ehci-omap.c
View File

@ -28,18 +28,21 @@ static struct omap_ehci *const ehci = (struct omap_ehci *)OMAP_EHCI_BASE;
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;
}