Re: [PATCH] usb: xhci: return an error if the host is not halted

[Michal Pecio <michal.pecio@gmail.com>]

On Wed,  2 Sep 2026 18:15:10 +0800, Henry Tseng wrote:
> xhci_reset() returns 0 when the host is not halted, without ever writing
> CMD_RESET. Every other path that fails to reset the host returns an
> error, so callers that check the return value are told the reset
> succeeded on the one path where it did not happen.
> 
> Return -EBUSY when the reset is aborted because the host is not halted.
> 
> Signed-off-by: Henry Tseng <henrytseng@qnap.com>
> ---
>  drivers/usb/host/xhci.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/drivers/usb/host/xhci.c b/drivers/usb/host/xhci.c
> index a9e47e178c28..2af6a7b91e55 100644
> --- a/drivers/usb/host/xhci.c
> +++ b/drivers/usb/host/xhci.c
> @@ -195,7 +195,7 @@ int xhci_reset(struct xhci_hcd *xhci, u64 timeout_us)
>  
>  	if ((state & STS_HALT) == 0) {
>  		xhci_warn(xhci, "Host controller not halted, aborting reset.\n");
> -		return 0;
> +		return -EBUSY;

That's probably how it should be, but I wonder how did you find this
bug and are you aware of any cases where it makes a difference?

There is apparently one caller (xhci_resume()) which cares about
xhci_reset() return value but not about the preceding xhci_halt().
 
>  	}
>  
>  	xhci_dbg_trace(xhci, trace_xhci_dbg_init, "// Reset the HC");
> -- 
> 2.43.0
>