Re: [PATCH] [RFC] xhci: Add Link TRB sync quirk for ASM3142

[Greg KH <greg@kroah.com>]

On Fri, Apr 16, 2021 at 11:37:29AM +0200, Ole Salscheider wrote:
> This patch adds a quirk to the xhci driver so that link TRBs are only
> given to the host controller once it has processed all previous TRBs on
> this segment.
> 
> This quirk is necessary for me on an ASMedia ASM3142 host controller.
> Without it, I get the following errors when accessing a SuperSpeed UVC
> camera:
> 
> Transfer event TRB DMA ptr not part of current TD ep_index XX comp_code XX
> 
> You can find more details in my previous mail about the problem:
> https://lkml.org/lkml/2021/3/31/355

Please use links to lore.kernel.org instead, we have no idea if lkml.org
will be around tomorrow or not.

> 
> This patch fixes my problem, but it is probably terribly wrong. I am not
> even sure if I can rely on handle_tx_event being called before each link
> TRB in the segment. Some feedback would be very welcome.
> ---
>  drivers/usb/host/xhci-pci.c  |  4 +++-
>  drivers/usb/host/xhci-ring.c | 34 ++++++++++++++++++++++++++++++----
>  drivers/usb/host/xhci.h      |  1 +
>  3 files changed, 34 insertions(+), 5 deletions(-)
> 
> diff --git a/drivers/usb/host/xhci-pci.c b/drivers/usb/host/xhci-pci.c
> index 5bbccc9a0179..4b02ac34934e 100644
> --- a/drivers/usb/host/xhci-pci.c
> +++ b/drivers/usb/host/xhci-pci.c
> @@ -284,8 +284,10 @@ static void xhci_pci_quirks(struct device *dev, struct xhci_hcd *xhci)
>  	if (pdev->vendor == PCI_VENDOR_ID_ASMEDIA &&
>  	    (pdev->device == PCI_DEVICE_ID_ASMEDIA_1142_XHCI ||
>  	     pdev->device == PCI_DEVICE_ID_ASMEDIA_2142_XHCI ||
> -	     pdev->device == PCI_DEVICE_ID_ASMEDIA_3242_XHCI))
> +	     pdev->device == PCI_DEVICE_ID_ASMEDIA_3242_XHCI)) {
>  		xhci->quirks |= XHCI_NO_64BIT_SUPPORT;
> +		xhci->quirks |= XHCI_SYNC_ON_LINK_TRB;
> +	}
>  
>  	if (pdev->vendor == PCI_VENDOR_ID_ASMEDIA &&
>  		pdev->device == PCI_DEVICE_ID_ASMEDIA_1042A_XHCI)
> diff --git a/drivers/usb/host/xhci-ring.c b/drivers/usb/host/xhci-ring.c
> index ce38076901e2..17f9484f1b0d 100644
> --- a/drivers/usb/host/xhci-ring.c
> +++ b/drivers/usb/host/xhci-ring.c
> @@ -257,8 +257,13 @@ static void inc_enq(struct xhci_hcd *xhci, struct xhci_ring *ring,
>  			next->link.control |= cpu_to_le32(chain);
>  		}
>  		/* Give this link TRB to the hardware */
> -		wmb();
> -		next->link.control ^= cpu_to_le32(TRB_CYCLE);
> +		if (!(xhci->quirks & XHCI_SYNC_ON_LINK_TRB) ||
> +				(ring->type != TYPE_BULK &&
> +				 ring->type != TYPE_STREAM &&
> +				 ring->type != TYPE_COMMAND)) {
> +			wmb();
> +			next->link.control ^= cpu_to_le32(TRB_CYCLE);
> +		}
>  
>  		/* Toggle the cycle bit after the last ring segment. */
>  		if (link_trb_toggles_cycle(next))
> @@ -2530,6 +2535,8 @@ static int handle_tx_event(struct xhci_hcd *xhci,
>  	dma_addr_t ep_trb_dma;
>  	struct xhci_segment *ep_seg;
>  	union xhci_trb *ep_trb;
> +	union xhci_trb *next_ep_trb;
> +	int next_ep_trb_idx;
>  	int status = -EINPROGRESS;
>  	struct xhci_ep_ctx *ep_ctx;
>  	struct list_head *tmp;
> @@ -2860,6 +2867,20 @@ static int handle_tx_event(struct xhci_hcd *xhci,
>  		else
>  			process_bulk_intr_td(xhci, td, ep_trb, event, ep);
>  cleanup:
> +		if (xhci->quirks & XHCI_SYNC_ON_LINK_TRB &&
> +				(ep_ring->type == TYPE_BULK ||
> +				 ep_ring->type == TYPE_STREAM ||
> +				 ep_ring->type == TYPE_COMMAND)) {
> +			next_ep_trb_idx = (ep_trb_dma - ep_seg->dma) /
> +				sizeof(*ep_trb) + 1;
> +			next_ep_trb = ep_trb = &ep_seg->trbs[next_ep_trb_idx];
> +			if (next_ep_trb_idx < TRBS_PER_SEGMENT &&
> +					trb_is_link(next_ep_trb)) {
> +				wmb();
> +				next_ep_trb->link.control ^= cpu_to_le32(TRB_CYCLE);
> +			}
> +		}
> +
>  		handling_skipped_tds = ep->skip &&
>  			trb_comp_code != COMP_MISSED_SERVICE_ERROR &&
>  			trb_comp_code != COMP_NO_PING_RESPONSE_ERROR;
> @@ -3192,8 +3213,13 @@ static int prepare_ring(struct xhci_hcd *xhci, struct xhci_ring *ep_ring,
>  			ep_ring->enqueue->link.control |=
>  				cpu_to_le32(TRB_CHAIN);
>  
> -		wmb();
> -		ep_ring->enqueue->link.control ^= cpu_to_le32(TRB_CYCLE);
> +		if (!(xhci->quirks & XHCI_SYNC_ON_LINK_TRB) ||
> +				(ep_ring->type != TYPE_BULK &&
> +				 ep_ring->type != TYPE_STREAM &&
> +				 ep_ring->type != TYPE_COMMAND)) {
> +			wmb();
> +			ep_ring->enqueue->link.control ^= cpu_to_le32(TRB_CYCLE);
> +		}
>  
>  		/* Toggle the cycle bit after the last ring segment. */
>  		if (link_trb_toggles_cycle(ep_ring->enqueue))
> diff --git a/drivers/usb/host/xhci.h b/drivers/usb/host/xhci.h
> index ca822ad3b65b..fd98f86cde37 100644
> --- a/drivers/usb/host/xhci.h
> +++ b/drivers/usb/host/xhci.h
> @@ -1892,6 +1892,7 @@ struct xhci_hcd {
>  #define XHCI_DISABLE_SPARSE	BIT_ULL(38)
>  #define XHCI_SG_TRB_CACHE_SIZE_QUIRK	BIT_ULL(39)
>  #define XHCI_NO_SOFT_RETRY	BIT_ULL(40)
> +#define XHCI_SYNC_ON_LINK_TRB	BIT_ULL(41)
>  
>  	unsigned int		num_active_eps;
>  	unsigned int		limit_active_eps;
> -- 
> 2.25.1
> 

Hi,

This is the friendly patch-bot of Greg Kroah-Hartman.  You have sent him
a patch that has triggered this response.  He used to manually respond
to these common problems, but in order to save his sanity (he kept
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created.  Hopefully you will not take offence and will fix the problem
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