Re: [PATCH 2/2] USB: ehci-platform: Support ehci reset after resume quirk

[Alan Stern]

On Mon, 22 Dec 2014, Wu Liang feng wrote:

> The EHCI controller doesn't properly detect the case when

"The" EHCI controller?  I don't know what EHCI controller you're 
talking about, but my controllers don't have any trouble detecting 
device removal during suspend.

> a device is removed during suspend. Specifically,when we
> resume from suspend the EHCI controller maintaining the
> USB state (FLAG_CF is 1 Current Connect Status is 1) but
> a USB device (like a USB camera on rk3288) may have been
> disconnected actually.
> 
> Let's add a quirk to force ehci to go into the
> usb_root_hub_lost_power() path and reset after resume.
> This should generally reset the whole controller and all
> ports and initialize everything cleanly again, and bring
> the devices back up.

Isn't this solution too extreme?  What if the device was a flash 
storage drive and it wasn't unplugged during suspend?  This patch would 
force it to be removed, messing up any mounted filesystems, when there 
was no need.

Can you find a better way to work around the problem?

Alan Stern

--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/