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Date: Mon, 10 Feb 2020 16:31:15 +0200
From: Mathias Nyman <mathias.nyman@...ux.intel.com>
To: Kai-Heng Feng <kai.heng.feng@...onical.com>,
mathias.nyman@...el.com, gregkh@...uxfoundation.org,
stern@...land.harvard.edu
Cc: acelan.kao@...onical.com, linux-usb@...r.kernel.org,
linux-kernel@...r.kernel.org
Subject: Re: [RESEND] [PATCH v2 2/3] xhci: Wait until link state trainsits to
U0 after setting USB_SS_PORT_LS_U0
On 5.2.2020 13.26, Kai-Heng Feng wrote:
> Like U3 case, xHCI spec doesn't specify the upper bound of U0 transition
> time. The 20ms is not enough for some devices.
>
> Intead of polling PLS or PLC, we can facilitate the port change event to
> know that the link transits to U0 is completed.
>
> While at it, also separate U0 and U3 case to make the code cleaner.
>
> Signed-off-by: Kai-Heng Feng <kai.heng.feng@...onical.com>
> ---
> v2:
> - Seperate U0 and U3 case.
> - Prevent setting U0 from non-U state.
> - Move the completion from per port to bus_state.
>
> drivers/usb/host/xhci-hub.c | 43 +++++++++++++++++++++++++-----------
> drivers/usb/host/xhci-mem.c | 2 ++
> drivers/usb/host/xhci-ring.c | 1 +
> drivers/usb/host/xhci.h | 1 +
> 4 files changed, 34 insertions(+), 13 deletions(-)
>
> diff --git a/drivers/usb/host/xhci-hub.c b/drivers/usb/host/xhci-hub.c
> index d3c5bcf76755..0a5d8b28b99f 100644
> --- a/drivers/usb/host/xhci-hub.c
> +++ b/drivers/usb/host/xhci-hub.c
> @@ -1297,7 +1297,32 @@ int xhci_hub_control(struct usb_hcd *hcd, u16 typeReq, u16 wValue,
> wIndex, link_state);
> goto error;
> }
> +
> + if (link_state == USB_SS_PORT_LS_U0) {
> + if ((temp & PORT_PLS_MASK) == XDEV_U0)
> + break;
> +
> + if (!((temp & PORT_PLS_MASK) == XDEV_U1 ||
> + (temp & PORT_PLS_MASK) == XDEV_U2 ||
> + (temp & PORT_PLS_MASK) == XDEV_U3)) {
> + xhci_warn(xhci, "Can only set port %d to U0 from U state\n",
> + wIndex);
Port link state could be XDEV_RESUME or maybe even XDEV_RECOVERY if we race with a device
initiated resume.
I'll need to check how we should handle those.
> + goto error;
> + }
> + reinit_completion(&bus_state->link_change_done[wIndex]);
> + xhci_set_link_state(xhci, ports[wIndex], USB_SS_PORT_LS_U0);
> + spin_unlock_irqrestore(&xhci->lock, flags);
> + if (!wait_for_completion_timeout(&bus_state->link_change_done[wIndex],
> + msecs_to_jiffies(100)))
Minor nit: rename link_change_done[] to u3exit_done[]
see xhci 4.19.1.2.13.2 "U3", and the Host Initiated resume substate transition
> + xhci_dbg(xhci, "missing U0 port change event for port %d\n",
> + wIndex);
> + spin_lock_irqsave(&xhci->lock, flags);
> + temp = readl(ports[wIndex]->addr);
> + break;
> + }
> +
> if (link_state == USB_SS_PORT_LS_U3) {
> + int retries = 10;
> slot_id = xhci_find_slot_id_by_port(hcd, xhci,
> wIndex + 1);
> if (slot_id) {
> @@ -1308,26 +1333,18 @@ int xhci_hub_control(struct usb_hcd *hcd, u16 typeReq, u16 wValue,
> xhci_stop_device(xhci, slot_id, 1);
> spin_lock_irqsave(&xhci->lock, flags);
> }
> - }
> -
> - xhci_set_link_state(xhci, ports[wIndex], link_state);
> -
> - spin_unlock_irqrestore(&xhci->lock, flags);
> - if (link_state == USB_SS_PORT_LS_U3) {
> - int retries = 10;
> -
> + xhci_set_link_state(xhci, ports[wIndex], USB_SS_PORT_LS_U3);
> + spin_unlock_irqrestore(&xhci->lock, flags);
> while (retries--) {
> msleep(10); /* wait device to enter */
> temp = readl(ports[wIndex]->addr);
> if ((temp & PORT_PLS_MASK) == XDEV_U3)
> break;
> }
> - }
> - spin_lock_irqsave(&xhci->lock, flags);
> -
> - temp = readl(ports[wIndex]->addr);
> - if (link_state == USB_SS_PORT_LS_U3)
> + spin_lock_irqsave(&xhci->lock, flags);
> + temp = readl(ports[wIndex]->addr);
> bus_state->suspended_ports |= 1 << wIndex;
> + }
> break;
> case USB_PORT_FEAT_POWER:
> /*
> diff --git a/drivers/usb/host/xhci-mem.c b/drivers/usb/host/xhci-mem.c
> index 3b1388fa2f36..aceb8c1af775 100644
> --- a/drivers/usb/host/xhci-mem.c
> +++ b/drivers/usb/host/xhci-mem.c
> @@ -2531,6 +2531,8 @@ int xhci_mem_init(struct xhci_hcd *xhci, gfp_t flags)
> xhci->usb3_rhub.bus_state.resume_done[i] = 0;
> /* Only the USB 2.0 completions will ever be used. */
> init_completion(&xhci->usb2_rhub.bus_state.rexit_done[i]);
> + init_completion(&xhci->usb2_rhub.bus_state.link_change_done[i]);
Not needed for usb2, it doesn't support Set Port Feature PORT_LINK_STATE requests
> + init_completion(&xhci->usb3_rhub.bus_state.link_change_done[i]);
rename to u3exit_done
> }
>
> if (scratchpad_alloc(xhci, flags))
> diff --git a/drivers/usb/host/xhci-ring.c b/drivers/usb/host/xhci-ring.c
> index d23f7408c81f..4d0f8dab069a 100644
> --- a/drivers/usb/host/xhci-ring.c
> +++ b/drivers/usb/host/xhci-ring.c
> @@ -1677,6 +1677,7 @@ static void handle_port_status(struct xhci_hcd *xhci,
> (portsc & PORT_PLS_MASK) == XDEV_U1 ||
> (portsc & PORT_PLS_MASK) == XDEV_U2)) {
> xhci_dbg(xhci, "resume SS port %d finished\n", port_id);
> + complete(&bus_state->link_change_done[hcd_portnum]);
> /* We've just brought the device into U0/1/2 through either the
> * Resume state after a device remote wakeup, or through the
> * U3Exit state after a host-initiated resume. If it's a device
> diff --git a/drivers/usb/host/xhci.h b/drivers/usb/host/xhci.h
> index 13d8838cd552..b5d443ce0750 100644
> --- a/drivers/usb/host/xhci.h
> +++ b/drivers/usb/host/xhci.h
> @@ -1694,6 +1694,7 @@ struct xhci_bus_state {
> /* Which ports are waiting on RExit to U0 transition. */
> unsigned long rexit_ports;
> struct completion rexit_done[USB_MAXCHILDREN];
> + struct completion link_change_done[USB_MAXCHILDREN];
> };
>
>
I can do these minor changes and try out these first two patches.
No need to resend.
The last 3/3 patch isn't really tied to the first two, or even xhci,
and should probably go as a separate patch.
-Mathias
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