76b8db0d48
On some platforms(e.g. rk3399 board), we can call hcd_add/remove consecutively without calling usb_put_hcd/usb_create_hcd in between, so hcd->flags can be stale. If the HC dies due to whatever reason then without this patch we get the below error on next hcd_add. [173.296154] xhci-hcd xhci-hcd.2.auto: HC died; cleaning up [173.296209] xhci-hcd xhci-hcd.2.auto: xHCI Host Controller [173.296762] xhci-hcd xhci-hcd.2.auto: new USB bus registered, assigned bus number 6 [173.296931] usb usb6: We don't know the algorithms for LPM for this host, disabling LPM. [173.297179] usb usb6: New USB device found, idVendor=1d6b, idProduct=0003 [173.297203] usb usb6: New USB device strings: Mfr=3, Product=2, SerialNumber=1 [173.297222] usb usb6: Product: xHCI Host Controller [173.297240] usb usb6: Manufacturer: Linux 4.4.21 xhci-hcd [173.297257] usb usb6: SerialNumber: xhci-hcd.2.auto [173.298680] hub 6-0:1.0: USB hub found [173.298749] hub 6-0:1.0: 1 port detected [173.299382] rockchip-dwc3 usb@fe800000: USB HOST connected [173.395418] hub 5-0:1.0: activate --> -19 [173.603447] irq 228: nobody cared (try booting with the "irqpoll" option) [173.603493] CPU: 0 PID: 0 Comm: swapper/0 Not tainted 4.4.21 #9 [173.603513] Hardware name: Google Kevin (DT) [173.603531] Call trace: [173.603568] [<ffffffc0002087dc>] dump_backtrace+0x0/0x160 [173.603596] [<ffffffc00020895c>] show_stack+0x20/0x28 [173.603623] [<ffffffc0004b28a8>] dump_stack+0x90/0xb0 [173.603650] [<ffffffc00027347c>] __report_bad_irq+0x48/0xe8 [173.603674] [<ffffffc0002737cc>] note_interrupt+0x1e8/0x28c [173.603698] [<ffffffc000270a38>] handle_irq_event_percpu+0x1d4/0x25c [173.603722] [<ffffffc000270b0c>] handle_irq_event+0x4c/0x7c [173.603748] [<ffffffc00027456c>] handle_fasteoi_irq+0xb4/0x124 [173.603777] [<ffffffc00026fe3c>] generic_handle_irq+0x30/0x44 [173.603804] [<ffffffc0002701a8>] __handle_domain_irq+0x90/0xbc [173.603827] [<ffffffc0002006f4>] gic_handle_irq+0xcc/0x188 ... [173.604500] [<ffffffc000203700>] el1_irq+0x80/0xf8 [173.604530] [<ffffffc000261388>] cpu_startup_entry+0x38/0x3cc [173.604558] [<ffffffc00090f7d8>] rest_init+0x8c/0x94 [173.604585] [<ffffffc000e009ac>] start_kernel+0x3d0/0x3fc [173.604607] [<0000000000b16000>] 0xb16000 [173.604622] handlers: [173.604648] [<ffffffc000642084>] usb_hcd_irq [173.604673] Disabling IRQ #228 Signed-off-by: William wu <wulf@rock-chips.com> Acked-by: Roger Quadros <rogerq@ti.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
To understand all the Linux-USB framework, you'll use these resources:
* This source code. This is necessarily an evolving work, and
includes kerneldoc that should help you get a current overview.
("make pdfdocs", and then look at "usb.pdf" for host side and
"gadget.pdf" for peripheral side.) Also, Documentation/usb has
more information.
* The USB 2.0 specification (from www.usb.org), with supplements
such as those for USB OTG and the various device classes.
The USB specification has a good overview chapter, and USB
peripherals conform to the widely known "Chapter 9".
* Chip specifications for USB controllers. Examples include
host controllers (on PCs, servers, and more); peripheral
controllers (in devices with Linux firmware, like printers or
cell phones); and hard-wired peripherals like Ethernet adapters.
* Specifications for other protocols implemented by USB peripheral
functions. Some are vendor-specific; others are vendor-neutral
but just standardized outside of the www.usb.org team.
Here is a list of what each subdirectory here is, and what is contained in
them.
core/ - This is for the core USB host code, including the
usbfs files and the hub class driver ("hub_wq").
host/ - This is for USB host controller drivers. This
includes UHCI, OHCI, EHCI, and others that might
be used with more specialized "embedded" systems.
gadget/ - This is for USB peripheral controller drivers and
the various gadget drivers which talk to them.
Individual USB driver directories. A new driver should be added to the
first subdirectory in the list below that it fits into.
image/ - This is for still image drivers, like scanners or
digital cameras.
../input/ - This is for any driver that uses the input subsystem,
like keyboard, mice, touchscreens, tablets, etc.
../media/ - This is for multimedia drivers, like video cameras,
radios, and any other drivers that talk to the v4l
subsystem.
../net/ - This is for network drivers.
serial/ - This is for USB to serial drivers.
storage/ - This is for USB mass-storage drivers.
class/ - This is for all USB device drivers that do not fit
into any of the above categories, and work for a range
of USB Class specified devices.
misc/ - This is for all USB device drivers that do not fit
into any of the above categories.