Re: How to perform runtime pm for usb hcds?

[Alan Stern <stern@xxxxxxxxxxxxxxxxxxx>]

On Mon, 19 Nov 2007, jidong xiao wrote:

> Hi,
>   I saw usb_hcd_pci_suspend() is stored in several HCD's struct
> pci_driver as suspend, and usb_hcd_pci_resume() is stored as
> resume().From user's perspective, is it possible to call these methods
> manually?I mean,I am using kdb the trace these methods,and I wanna set
> a breakpoint in the point whenever these two methods are invoked.
> That's to say, once either of these two methods are invoked, then the
> system will drop into kdb, so that I can do some analysis on these two
> methods. But the problem is, from user space,what shall I do to
> trigger these two methods?

Here's a patch to create a sysfs file for PCI devices.  Writing 1 to 
the file will call the device's suspend method, and writing 0 will call 
the resume method.

Alan Stern



Index: linux/drivers/pci/pci-sysfs.c
===================================================================
--- linux.orig/drivers/pci/pci-sysfs.c	2007-10-26 09:33:12.000000000 +0800
+++ linux/drivers/pci/pci-sysfs.c	2007-10-26 09:33:27.000000000 +0800
@@ -192,6 +192,22 @@ msi_bus_store(struct device *dev, struct
 	return count;
 }
 
+static ssize_t
+suspend_store(struct device *dev, struct device_attribute *attr,
+		const char *buf, size_t count)
+{
+	int rc;
+
+	if (*buf == '1')
+		rc = dev->bus->suspend(dev, PMSG_SUSPEND);
+	else if (*buf == '0')
+		rc = dev->bus->resume(dev);
+	else
+		rc = -EIO;
+	return (rc < 0 ? rc : count);
+}
+
+
 struct device_attribute pci_dev_attrs[] = {
 	__ATTR_RO(resource),
 	__ATTR_RO(vendor),
@@ -209,6 +225,7 @@ struct device_attribute pci_dev_attrs[] 
 	__ATTR(broken_parity_status,(S_IRUGO|S_IWUSR),
 		broken_parity_status_show,broken_parity_status_store),
 	__ATTR(msi_bus, 0644, msi_bus_show, msi_bus_store),
+	__ATTR(suspend, 0200, NULL, suspend_store),
 	__ATTR_NULL,
 };
 


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