On 12/11/2012 08:13 PM, Alan Stern wrote:
On Tue, 11 Dec 2012, Timur wrote:
Thank you for your response. Yes, unplugging helps. But host and slave
should also function in a fixed installation setup, where cables are
hidden. I tried different slave devices and they are all "not
accepting address xx, error -71" after power was lost.
I think it is the host causing the issue, not working properly through
it's deep sleep cycle. Something is wrong or missing in N7's
tegra_ehci_resume() / tegra_ehci_suspend() methods. These methods
exist (found them!) and they are being called:
https://github.com/mehrvarz/android_kernel_grouper/blob/android-tegra3-grouper-3.1-jb-mr0/drivers/usb/host/ehci-tegra.c#L1246
A power loss of under 20s will make the host only go into light sleep
and does not result in error -71.
Are you talking about a loss of power to the host or a loss of power to
the slave?
What is the cause of this power loss?
If you think this problem is specifically related to the Tegra, why not
ask the person responsible for maintaining the Tegra code? (Hint: Look
in the MAINTAINERS file at the top level of the kernel source code.)
Alan Stern
I am talking about both devices loosing external power at the same time.
The N7 will then switch to it's internal battery.
I guess anything could cause a loss of power. Turning off the car
ignition, for example.
Good hint. I found a reference to linux-tegra and will contact them.
Allow me to say that I got a little scared when you told me to "try
unplugging the slave" as a solution. Maybe you weren't all serious with
a list newbie?
Timur
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