Date:	Wed, 30 Apr 2014 16:31:53 -0700
From:	Sarah Sharp <sarah.a.sharp@...ux.intel.com>
To:	Julius Werner <jwerner@...omium.org>
Cc:	Mathias Nyman <mathias.nyman@...ux.intel.com>,
	Alan Stern <stern@...land.harvard.edu>,
	Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
	Vincent Palatin <vpalatin@...omium.org>,
	Andrew Bresticker <abrestic@...omium.org>,
	Jim Lin <jilin@...dia.com>, linux-usb@...r.kernel.org,
	linux-kernel@...r.kernel.org
Subject: Re: [PATCH v2] usb: xhci: Correct last context entry calculation for
 Configure Endpoint

Script is attached now.

Sarah

On Wed, Apr 30, 2014 at 04:04:24PM -0700, Sarah Sharp wrote:
> Hi Mathias,
> 
> I tested both this patch and your global command queue patches on top of
> your for-usb-linus branch.  After reverting commit 400362f1d8dc "ALSA:
> usb-audio: Resume mixer values properly", I was able to get my USB
> webcam working. [1]
> 
> I wrote a small shell script (attached) to start and kill guvcview over
> and over, so that I could test the xHCI driver issuing Configure
> Endpoint commands, and proceeded to plug and unplug a VIA USB 3.0 hub in
> over and over again.  I got occasional descriptor fetch errors and once
> saw a Set Address timeout, and everything seemed to work as expected.
> 
> In short, I think it's fine to merge Julius' patch to usb-linus and your
> command queue patches to usb-next.
> 
> Sarah Sharp
> 
> [1] https://lkml.org/lkml/2014/4/19/117
> 
> On Tue, Apr 29, 2014 at 10:38:17AM -0700, Julius Werner wrote:
> > The current XHCI driver recalculates the Context Entries field in the
> > Slot Context on every add_endpoint() and drop_endpoint() call. In the
> > case of drop_endpoint(), it seems to assume that the add_flags will
> > always contain every endpoint for the new configuration, which is not
> > necessarily correct if you don't make assumptions about how the USB core
> > uses the add_endpoint/drop_endpoint interface (add_flags only contains
> > endpoints that are new additions in the new configuration).
> > 
> > Furthermore, EP0_FLAG is not consistently set in add_flags throughout
> > the lifetime of a device. This means that when all endpoints are
> > dropped, the Context Entries field can be set to 0 (which is invalid and
> > may cause a Parameter Error) or -1 (which is interpreted as 31 and
> > causes the driver to keep using the old, incorrect value).
> > 
> > The only surefire way to set this field right is to also take all
> > existing endpoints into account, and to force the value to 1 (meaning
> > only EP0 is active) if no other endpoint is found. This patch implements
> > that as a single step in the final check_bandwidth() call and removes
> > the intermediary calculations from add_endpoint() and drop_endpoint().
> > 
> > Signed-off-by: Julius Werner <jwerner@...omium.org>
> > ---
> >  drivers/usb/host/xhci.c | 51 +++++++++++++++++--------------------------------
> >  1 file changed, 18 insertions(+), 33 deletions(-)
> > 
> > diff --git a/drivers/usb/host/xhci.c b/drivers/usb/host/xhci.c
> > index 924a6cc..fec6423 100644
> > --- a/drivers/usb/host/xhci.c
> > +++ b/drivers/usb/host/xhci.c
> > @@ -1562,12 +1562,10 @@ int xhci_drop_endpoint(struct usb_hcd *hcd, struct usb_device *udev,
> >  	struct xhci_hcd *xhci;
> >  	struct xhci_container_ctx *in_ctx, *out_ctx;
> >  	struct xhci_input_control_ctx *ctrl_ctx;
> > -	struct xhci_slot_ctx *slot_ctx;
> > -	unsigned int last_ctx;
> >  	unsigned int ep_index;
> >  	struct xhci_ep_ctx *ep_ctx;
> >  	u32 drop_flag;
> > -	u32 new_add_flags, new_drop_flags, new_slot_info;
> > +	u32 new_add_flags, new_drop_flags;
> >  	int ret;
> >  
> >  	ret = xhci_check_args(hcd, udev, ep, 1, true, __func__);
> > @@ -1614,24 +1612,13 @@ int xhci_drop_endpoint(struct usb_hcd *hcd, struct usb_device *udev,
> >  	ctrl_ctx->add_flags &= cpu_to_le32(~drop_flag);
> >  	new_add_flags = le32_to_cpu(ctrl_ctx->add_flags);
> >  
> > -	last_ctx = xhci_last_valid_endpoint(le32_to_cpu(ctrl_ctx->add_flags));
> > -	slot_ctx = xhci_get_slot_ctx(xhci, in_ctx);
> > -	/* Update the last valid endpoint context, if we deleted the last one */
> > -	if ((le32_to_cpu(slot_ctx->dev_info) & LAST_CTX_MASK) >
> > -	    LAST_CTX(last_ctx)) {
> > -		slot_ctx->dev_info &= cpu_to_le32(~LAST_CTX_MASK);
> > -		slot_ctx->dev_info |= cpu_to_le32(LAST_CTX(last_ctx));
> > -	}
> > -	new_slot_info = le32_to_cpu(slot_ctx->dev_info);
> > -
> >  	xhci_endpoint_zero(xhci, xhci->devs[udev->slot_id], ep);
> >  
> > -	xhci_dbg(xhci, "drop ep 0x%x, slot id %d, new drop flags = %#x, new add flags = %#x, new slot info = %#x\n",
> > +	xhci_dbg(xhci, "drop ep 0x%x, slot id %d, new drop flags = %#x, new add flags = %#x\n",
> >  			(unsigned int) ep->desc.bEndpointAddress,
> >  			udev->slot_id,
> >  			(unsigned int) new_drop_flags,
> > -			(unsigned int) new_add_flags,
> > -			(unsigned int) new_slot_info);
> > +			(unsigned int) new_add_flags);
> >  	return 0;
> >  }
> >  
> > @@ -1654,11 +1641,9 @@ int xhci_add_endpoint(struct usb_hcd *hcd, struct usb_device *udev,
> >  	struct xhci_hcd *xhci;
> >  	struct xhci_container_ctx *in_ctx, *out_ctx;
> >  	unsigned int ep_index;
> > -	struct xhci_slot_ctx *slot_ctx;
> >  	struct xhci_input_control_ctx *ctrl_ctx;
> >  	u32 added_ctxs;
> > -	unsigned int last_ctx;
> > -	u32 new_add_flags, new_drop_flags, new_slot_info;
> > +	u32 new_add_flags, new_drop_flags;
> >  	struct xhci_virt_device *virt_dev;
> >  	int ret = 0;
> >  
> > @@ -1673,7 +1658,6 @@ int xhci_add_endpoint(struct usb_hcd *hcd, struct usb_device *udev,
> >  		return -ENODEV;
> >  
> >  	added_ctxs = xhci_get_endpoint_flag(&ep->desc);
> > -	last_ctx = xhci_last_valid_endpoint(added_ctxs);
> >  	if (added_ctxs == SLOT_FLAG || added_ctxs == EP0_FLAG) {
> >  		/* FIXME when we have to issue an evaluate endpoint command to
> >  		 * deal with ep0 max packet size changing once we get the
> > @@ -1739,24 +1723,14 @@ int xhci_add_endpoint(struct usb_hcd *hcd, struct usb_device *udev,
> >  	 */
> >  	new_drop_flags = le32_to_cpu(ctrl_ctx->drop_flags);
> >  
> > -	slot_ctx = xhci_get_slot_ctx(xhci, in_ctx);
> > -	/* Update the last valid endpoint context, if we just added one past */
> > -	if ((le32_to_cpu(slot_ctx->dev_info) & LAST_CTX_MASK) <
> > -	    LAST_CTX(last_ctx)) {
> > -		slot_ctx->dev_info &= cpu_to_le32(~LAST_CTX_MASK);
> > -		slot_ctx->dev_info |= cpu_to_le32(LAST_CTX(last_ctx));
> > -	}
> > -	new_slot_info = le32_to_cpu(slot_ctx->dev_info);
> > -
> >  	/* Store the usb_device pointer for later use */
> >  	ep->hcpriv = udev;
> >  
> > -	xhci_dbg(xhci, "add ep 0x%x, slot id %d, new drop flags = %#x, new add flags = %#x, new slot info = %#x\n",
> > +	xhci_dbg(xhci, "add ep 0x%x, slot id %d, new drop flags = %#x, new add flags = %#x\n",
> >  			(unsigned int) ep->desc.bEndpointAddress,
> >  			udev->slot_id,
> >  			(unsigned int) new_drop_flags,
> > -			(unsigned int) new_add_flags,
> > -			(unsigned int) new_slot_info);
> > +			(unsigned int) new_add_flags);
> >  	return 0;
> >  }
> >  
> > @@ -2723,8 +2697,19 @@ int xhci_check_bandwidth(struct usb_hcd *hcd, struct usb_device *udev)
> >  			ctrl_ctx->drop_flags == 0)
> >  		return 0;
> >  
> > -	xhci_dbg(xhci, "New Input Control Context:\n");
> > +	/* Fix up Context Entries field. Minimum value is EP0 == BIT(1). */
> >  	slot_ctx = xhci_get_slot_ctx(xhci, virt_dev->in_ctx);
> > +	for (i = 31; i >= 1; i--) {
> > +		__le32 le32 = cpu_to_le32(BIT(i));
> > +		if ((virt_dev->eps[i-1].ring && !(ctrl_ctx->drop_flags & le32))
> > +				|| (ctrl_ctx->add_flags & le32) || i == 1) {
> > +			slot_ctx->dev_info &= cpu_to_le32(~LAST_CTX_MASK);
> > +			slot_ctx->dev_info |= cpu_to_le32(LAST_CTX(i));
> > +			break;
> > +		}
> > +	}
> > +
> > +	xhci_dbg(xhci, "New Input Control Context:\n");
> >  	xhci_dbg_ctx(xhci, virt_dev->in_ctx,
> >  		     LAST_CTX_TO_EP_NUM(le32_to_cpu(slot_ctx->dev_info)));
> >  
> > -- 
> > 1.8.3.2
> > 
> --
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