Re: [PATCH 1/2] usb: hub: use shorter 120ms post resume hold for SS root hubs

[Lovekesh Solanki]

Thanks for the feedback,

On Wed, Sep 02, 2026 at 04:29:40PM +0300, Mathias Nyman wrote:
> I'd highlight the fact that this patch mitigates the AMD platform issue.
> 
> Maybe begin commit message with something like
> 
> "Holding a USB3 hub PM runtime reference for 200ms at hub resume triggers a
>  AMD platform issue. Users running Android adb report crashes after adb has
>  been polling and waking up the USB subsystem once a second for some time.
>  Vendors are working on a solution. Disabling USB runtime PM is one way to
>  prevent this issue, but it is also proven that reducing the hold time to 120ms in
>  resume also mitigates it. See Link for more details.
> 
>  Reducing the hold time to 120ms for the USB3 roothub is in itself a valid change
>  and optimization as the current 200ms is excessive...
> "
I will re work the commit message in v2 along those lines. But if the
mention of the commit 8f5b7e2bec1c is removed, should I keep the Fixes
tag or remove it as well?

> I'd do minor changes to the original code comment above the first #define,
> and just add the second define right after it
> 
> /*
>  * modified original comment
>  */
> #define USB_SS_PORT_U0_WAKE_TIME	200  /* ms */
> #define USB_SS_RH_PORT_U0_WAKE_TIME	120  /* ms */

I could change it to something like:

/*
 * Give SS hubs 200ms time after wake to train downstream links before
 * assuming no port activity and allowing hub to runtime suspend back.
 * Root hubs have no upstream hub whose wake propagation needs to be
 * accounted for, so they need less time, use 120ms for them.
 */
#define USB_SS_PORT_U0_WAKE_TIME	200  /* ms */
#define USB_SS_RH_PORT_U0_WAKE_TIME	120  /* ms */

If everything else's fine, I'll send a v2 with these changes.

Thanks,
Lovekesh