[Letux-kernel] [PATCH RFC] ehci-omap: simple suspend implementation

[Andreas Kemnade]

This powers down the phy and on a gta04 it reduces
suspend current by 13 mA.
For unknown reasons usb does not power on properly.
Also calling usb_phy_shutdown() here feels wrong
apparently the reset line has to be activated.
usb_phy_set_suspend is not enough here. The power
consumption still stays approximately the same as
without any patch.

With a device connected the device does not enumerate
after resume. A rmmod ehci-omap ; modprobe ehci-omap
does not make it reenumerade.
So there is still something wrong here.

Signed-off-by: Andreas Kemnade <andreas at kemnade.info>
---
 drivers/usb/host/ehci-omap.c | 59 ++++++++++++++++++++++++++++++++++++++++++--
 1 file changed, 57 insertions(+), 2 deletions(-)

diff --git a/drivers/usb/host/ehci-omap.c b/drivers/usb/host/ehci-omap.c
index 8d8bafc70c1f..0be2ccf8182a 100644
--- a/drivers/usb/host/ehci-omap.c
+++ b/drivers/usb/host/ehci-omap.c
@@ -266,6 +266,58 @@ static int ehci_hcd_omap_remove(struct platform_device *pdev)
 	return 0;
 }
 
+
+static int __maybe_unused ehci_omap_suspend(struct device *dev)
+{
+	struct usb_hcd *hcd = dev_get_drvdata(dev);
+	struct omap_hcd *omap = (struct omap_hcd *)hcd_to_ehci(hcd)->priv;
+	int ret;
+	int i;
+
+	ret = ehci_suspend(hcd, false);
+	if (ret) {
+		dev_err(dev, "ehci suspend failed: %d\n", ret);
+		return ret;
+	}
+	for (i = 0; i < omap->nports; i++) {
+		if (omap->phy[i])
+			usb_phy_shutdown(omap->phy[i]);
+	}
+	pm_runtime_put_sync(dev);
+
+	return 0;
+}
+
+static int __maybe_unused ehci_omap_resume(struct device *dev)
+{
+	struct usb_hcd *hcd = dev_get_drvdata(dev);
+	struct omap_hcd *omap = (struct omap_hcd *)hcd_to_ehci(hcd)->priv;
+	int i;
+
+	pm_runtime_get_sync(dev);
+	/*
+	 * 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(hcd->regs, EHCI_INSNREG04,
+		   EHCI_INSNREG04_DISABLE_UNSUSPEND);
+
+	for (i = 0; i < omap->nports; i++) {
+		if (omap->phy[i]) {
+			usb_phy_init(omap->phy[i]);
+			usb_phy_set_suspend(omap->phy[i], false);
+		}
+	}
+
+	ehci_resume(hcd, true);
+	return 0;
+}
+
 static const struct of_device_id omap_ehci_dt_ids[] = {
 	{ .compatible = "ti,ehci-omap" },
 	{ }
@@ -273,14 +325,17 @@ static const struct of_device_id omap_ehci_dt_ids[] = {
 
 MODULE_DEVICE_TABLE(of, omap_ehci_dt_ids);
 
+static SIMPLE_DEV_PM_OPS(ehci_omap_pm_ops, ehci_omap_suspend,
+			 ehci_omap_resume);
+
+
 static struct platform_driver ehci_hcd_omap_driver = {
 	.probe			= ehci_hcd_omap_probe,
 	.remove			= ehci_hcd_omap_remove,
 	.shutdown		= usb_hcd_platform_shutdown,
-	/*.suspend		= ehci_hcd_omap_suspend, */
-	/*.resume		= ehci_hcd_omap_resume, */
 	.driver = {
 		.name		= hcd_name,
+		.pm		= &ehci_omap_pm_ops,
 		.of_match_table = omap_ehci_dt_ids,
 	}
 };
-- 
2.11.0