Re: [PATCH] usb: xhci: Set avg_trb_len = 8 for EP0 during Address Device

["gregkh@linuxfoundation.org" <gregkh@linuxfoundation.org>]

On Tue, May 13, 2025 at 09:07:00AM +0000, Chen, Jay wrote:
> From fef893bcf0add89795b85bcc1f6bdae537f1dabe Mon Sep 17 00:00:00 2001
> From: "jay.chen" <jay.chen@siemens.com>
> Date: Tue, 13 May 2025 15:03:44 +0800
> Subject: [PATCH] usb: xhci: Set avg_trb_len = 8 for EP0 during Address Device
> Command
> 
> According to the xHCI 1.2 spec (Section 6.2.3, p.454), the Average
> TRB Length (avg_trb_len) for control endpoints should be set to 8.
> 
> Currently, during the Address Device Command, EP0's avg_trb_len remains 0,
> which may cause some xHCI hardware to reject the Input Context, resulting
> in device enumeration failures. In extreme cases, using a zero avg_trb_len
> in calculations may lead to division-by-zero errors and unexpected system
> crashes.
> 
> This patch sets avg_trb_len to 8 for EP0 in
> xhci_setup_addressable_virt_dev(), ensuring compliance with the spec
> and improving compatibility across various host controller implementations.
> 
> Link: https://bugzilla.kernel.org/show_bug.cgi?id=220033
> Signed-off-by: jay.chen <jay.chen@siemens.com>
> ---
> drivers/usb/host/xhci-mem.c | 2 ++
> 1 file changed, 2 insertions(+)
> 
> diff --git a/drivers/usb/host/xhci-mem.c b/drivers/usb/host/xhci-mem.c
> index d698095fc88d..fed9e9d1990c 100644
> --- a/drivers/usb/host/xhci-mem.c
> +++ b/drivers/usb/host/xhci-mem.c
> @@ -1166,6 +1166,8 @@ int xhci_setup_addressable_virt_dev(struct xhci_hcd *xhci, struct usb_device *ud
>       ep0_ctx->deq = cpu_to_le64(dev->eps[0].ring->first_seg->dma |
>                                  dev->eps[0].ring->cycle_state);
> 
> +      ep0_ctx->tx_info |= cpu_to_le32(EP_AVG_TRB_LENGTH(8));
> +
>       trace_xhci_setup_addressable_virt_device(dev);
> 
>        /* Steps 7 and 8 were done in xhci_alloc_virt_device() */
> -- 
> 2.43.5


Hi,

This is the friendly patch-bot of Greg Kroah-Hartman.  You have sent him
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