Help wanted with USB and OMAP3 off_mode

[NeilBrown <neilb@suse.de>]

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Hi,
 I'm trying to get off_mode working reliably on my gta04 mobile phone.

My current stumbling block is USB.  The "Option" GSM module is attached via
USB (there is a separate transceiver chip attached to port 1 which is placed
in OMAP_EHCI_PORT_MODE_PHY).

After a suspend/resume cycle with off_mode enabled the GSM module disappears.
i.e. 'lsusb' doesn't see it any more and the various ttyHSxx devices don't
exist.
Without off mode, the modem always appears after resume.

I discovered that the registers set by:

   drivers/mfd/omap-usb-host.c

are not maintained across as suspend/resume so I added the following patch
(which I can make a formal submission of if it looks right to others), but
that didn't help (or didn't help enough).

If I

  echo 1 > /sys/kernel/debug/pm_debug/usbhost_pwrdm/suspend

thus keeping just the USBHOST power domain out of off_mode, the GSM module
doesn't disappear.  So it seems that some context in the usbhost domain is
not being save and restored.

This is as far as I can get.  Can someone suggest where I should look to find
out what is not being saved/restored properly, and how to go about saving and
restoring?

Thanks in advance,
NeilBrown



diff --git a/drivers/mfd/omap-usb-host.c b/drivers/mfd/omap-usb-host.c
index 23cec57..522405e 100644
--- a/drivers/mfd/omap-usb-host.c
+++ b/drivers/mfd/omap-usb-host.c
@@ -100,6 +100,10 @@ struct usbhs_hcd_omap {
 
 	void __iomem			*uhh_base;
 
+	struct {
+		unsigned		hostconfig;
+	} context;
+
 	struct usbhs_omap_platform_data	platdata;
 
 	u32				usbhs_rev;
@@ -300,6 +304,10 @@ static int usbhs_runtime_resume(struct device *dev)
 	clk_enable(omap->utmi_p1_fck);
 	clk_enable(omap->utmi_p2_fck);
 
+	usbhs_write(omap->uhh_base,
+		    OMAP_UHH_HOSTCONFIG,
+		    omap->context.hostconfig);
+
 	spin_unlock_irqrestore(&omap->lock, flags);
 
 	return 0;
@@ -319,6 +327,8 @@ static int usbhs_runtime_suspend(struct device *dev)
 	}
 
 	spin_lock_irqsave(&omap->lock, flags);
+	omap->context.hostconfig = usbhs_read(omap->uhh_base,
+					      OMAP_UHH_HOSTCONFIG);
 
 	if (is_ehci_tll_mode(pdata->port_mode[0]))
 		clk_disable(omap->usbhost_p1_fck);

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