On Wed, Jun 27, 2012 at 7:54 PM, Alan Stern <stern@xxxxxxxxxxxxxxxxxxx> wrote:
> On Wed, 27 Jun 2012, Keshava Munegowda wrote:
>
>> Its observed that in Beagle XM , during suspend/resume the OMAP
>> EHCI controller losing the register contents. this is causing the
>> hub disconnect after the resume, this is causing failure of
>> device detection after the resume.
>> to avoid the hub disconnect , The ehci config flag register is
>> configured again , reset the phy and issue the port powers during
>> resume.
>
> The idea is good, but the implementation is wrong.
>
>> +static int omap_ehci_bus_resume(struct usb_hcd *hcd)
>> +{
>> +
>> + struct device *dev = hcd->self.controller;
>> + struct ehci_hcd_omap_platform_data *pdata = dev->platform_data;
>> + struct resource *regs = hcd->regs;
>> +
>> + /* In case , ports are not powered and config flag not set */
>> + if (~(ehci_read(regs, EHCI_CONFIGFLAG) & 0x01)) {
>> + ehci_write(regs, EHCI_CONFIGFLAG, 0x1);
>> +
>> + /*
>> + * An undocumented "feature" in the OMAP3 EHCI controller,
>> + * causes suspended ports to be taken out of suspend when
>> + * the USBCMD.Run/Stop bit is cleared (for example when
>> + * we do ehci_bus_suspend).
>> + * This breaks suspend-resume if the root-hub is allowed
>> + * to suspend. Writing 1 to this undocumented register bit
>> + * disables this feature and restores normal behavior.
>> + */
>> + ehci_write(regs, EHCI_INSNREG04,
>> + EHCI_INSNREG04_DISABLE_UNSUSPEND);
>> +
>> + /* Soft reset the PHY using PHY reset command over ULPI */
>> + if (pdata->port_mode[0] == OMAP_EHCI_PORT_MODE_PHY)
>> + omap_ehci_soft_phy_reset(dev, 0);
>> + if (pdata->port_mode[1] == OMAP_EHCI_PORT_MODE_PHY)
>> + omap_ehci_soft_phy_reset(dev, 1);
>> +
>> + /* root ports should always stay powered */
>> + ehci_port_power(hcd_to_ehci(hcd), 1);
>> + }
>
> This needs to be done in the resume routine, not the bus_resume
> routine. Since ehci-omap doesn't have any suspend or resume routines,
> it's not surprising that the controller doesn't work correctly after
> the system is resumed.
>
> In a couple of days I will submit a patch that will make it a lot
> easier to add suspend and resume routines for EHCI platform drivers.
> Maybe you'd prefer to wait until then to fix this issue.
>
> Alan Stern
Thanks Alan
Ok, I will wait for your patches.
regards
keshava
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