From 953c66469735aed8d2ada639a72b150f01dae605 Mon Sep 17 00:00:00 2001 From: Abbas Raza Date: Thu, 17 Jul 2014 19:34:31 +0800 Subject: [PATCH 1/2] usb: chipidea: udc: Disable auto ZLP generation on ep0 There are 2 methods for ZLP (zero-length packet) generation: 1) In software 2) Automatic generation by device controller 1) is implemented in UDC driver and it attaches ZLP to IN packet if descriptor->size < wLength 2) can be enabled/disabled by setting ZLT bit in the QH When gadget ffs is connected to ubuntu host, the host sends get descriptor request and wLength in setup packet is 255 while the size of descriptor which will be sent by gadget in IN packet is 64 byte. So the composite driver sets req->zero = 1. In UDC driver following code will be executed then if (hwreq->req.zero && hwreq->req.length && (hwreq->req.length % hwep->ep.maxpacket == 0)) add_td_to_list(hwep, hwreq, 0); Case-A: So in case of ubuntu host, UDC driver will attach a ZLP to the IN packet. ubuntu host will request 255 byte in IN request, gadget will send 64 byte with ZLP and host will come to know that there is no more data. But hold on, by default ZLT=0 for endpoint 0 so hardware also tries to automatically generate the ZLP which blocks enumeration for ~6 seconds due to endpoint 0 STALL, NAKs are sent to host for any requests (OUT/PING) Case-B: In case when gadget ffs is connected to Apple device, Apple device sends setup packet with wLength=64. So descriptor->size = 64 and wLength=64 therefore req->zero = 0 and UDC driver will not attach any ZLP to the IN packet. Apple device requests 64 bytes, gets 64 bytes and doesn't further request for IN data. But ZLT=0 by default for endpoint 0 so hardware tries to automatically generate the ZLP which blocks enumeration for ~6 seconds due to endpoint 0 STALL, NAKs are sent to host for any requests (OUT/PING) According to USB2.0 specs: 8.5.3.2 Variable-length Data Stage A control pipe may have a variable-length data phase in which the host requests more data than is contained in the specified data structure. When all of the data structure is returned to the host, the function should indicate that the Data stage is ended by returning a packet that is shorter than the MaxPacketSize for the pipe. If the data structure is an exact multiple of wMaxPacketSize for the pipe, the function will return a zero-length packet to indicate the end of the Data stage. In Case-A mentioned above: If we disable software ZLP generation & ZLT=0 for endpoint 0 OR if software ZLP generation is not disabled but we set ZLT=1 for endpoint 0 then enumeration doesn't block for 6 seconds. In Case-B mentioned above: If we disable software ZLP generation & ZLT=0 for endpoint then enumeration still blocks due to ZLP automatically generated by hardware and host not needing it. But if we keep software ZLP generation enabled but we set ZLT=1 for endpoint 0 then enumeration doesn't block for 6 seconds. So the proper solution for this issue seems to disable automatic ZLP generation by hardware (i.e by setting ZLT=1 for endpoint 0) and let software (UDC driver) handle the ZLP generation based on req->zero field. Cc: stable@vger.kernel.org Signed-off-by: Abbas Raza Signed-off-by: Peter Chen Signed-off-by: Greg Kroah-Hartman --- drivers/usb/chipidea/udc.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) diff --git a/drivers/usb/chipidea/udc.c b/drivers/usb/chipidea/udc.c index 9d2b673f90e3..b8125aa64ad8 100644 --- a/drivers/usb/chipidea/udc.c +++ b/drivers/usb/chipidea/udc.c @@ -1169,8 +1169,8 @@ static int ep_enable(struct usb_ep *ep, if (hwep->type == USB_ENDPOINT_XFER_CONTROL) cap |= QH_IOS; - if (hwep->num) - cap |= QH_ZLT; + + cap |= QH_ZLT; cap |= (hwep->ep.maxpacket << __ffs(QH_MAX_PKT)) & QH_MAX_PKT; /* * For ISO-TX, we set mult at QH as the largest value, and use From bb86cf569bbd7ad4dce581a37c7fbd748057e9dc Mon Sep 17 00:00:00 2001 From: Gavin Guo Date: Fri, 18 Jul 2014 01:12:13 +0800 Subject: [PATCH 2/2] usb: Check if port status is equal to RxDetect When using USB 3.0 pen drive with the [AMD] FCH USB XHCI Controller [1022:7814], the second hotplugging will experience the USB 3.0 pen drive is recognized as high-speed device. After bisecting the kernel, I found the commit number 41e7e056cdc662f704fa9262e5c6e213b4ab45dd (USB: Allow USB 3.0 ports to be disabled.) causes the bug. After doing some experiments, the bug can be fixed by avoiding executing the function hub_usb3_port_disable(). Because the port status with [AMD] FCH USB XHCI Controlleris [1022:7814] is already in RxDetect (I tried printing out the port status before setting to Disabled state), it's reasonable to check the port status before really executing hub_usb3_port_disable(). Fixes: 41e7e056cdc6 (USB: Allow USB 3.0 ports to be disabled.) Signed-off-by: Gavin Guo Acked-by: Alan Stern Cc: Signed-off-by: Greg Kroah-Hartman --- drivers/usb/core/hub.c | 19 +++++++++++++++++++ 1 file changed, 19 insertions(+) diff --git a/drivers/usb/core/hub.c b/drivers/usb/core/hub.c index 21b99b4b4082..0e950ad8cb25 100644 --- a/drivers/usb/core/hub.c +++ b/drivers/usb/core/hub.c @@ -889,6 +889,25 @@ static int hub_usb3_port_disable(struct usb_hub *hub, int port1) if (!hub_is_superspeed(hub->hdev)) return -EINVAL; + ret = hub_port_status(hub, port1, &portstatus, &portchange); + if (ret < 0) + return ret; + + /* + * USB controller Advanced Micro Devices, Inc. [AMD] FCH USB XHCI + * Controller [1022:7814] will have spurious result making the following + * usb 3.0 device hotplugging route to the 2.0 root hub and recognized + * as high-speed device if we set the usb 3.0 port link state to + * Disabled. Since it's already in USB_SS_PORT_LS_RX_DETECT state, we + * check the state here to avoid the bug. + */ + if ((portstatus & USB_PORT_STAT_LINK_STATE) == + USB_SS_PORT_LS_RX_DETECT) { + dev_dbg(&hub->ports[port1 - 1]->dev, + "Not disabling port; link state is RxDetect\n"); + return ret; + } + ret = hub_set_port_link_state(hub, port1, USB_SS_PORT_LS_SS_DISABLED); if (ret) return ret;