Message-ID: <575FBD6D.5010905@ti.com>
Date:	Tue, 14 Jun 2016 11:16:45 +0300
From:	Roger Quadros <rogerq@...com>
To:	Alan Stern <stern@...land.harvard.edu>
CC:	<peter.chen@...escale.com>, <balbi@...nel.org>, <tony@...mide.com>,
	<gregkh@...uxfoundation.org>, <dan.j.williams@...el.com>,
	<mathias.nyman@...ux.intel.com>, <Joao.Pinto@...opsys.com>,
	<sergei.shtylyov@...entembedded.com>, <jun.li@...escale.com>,
	<grygorii.strashko@...com>, <yoshihiro.shimoda.uh@...esas.com>,
	<robh@...nel.org>, <nsekhar@...com>, <b-liu@...com>,
	<joe@...ches.com>, <linux-usb@...r.kernel.org>,
	<linux-omap@...r.kernel.org>, <linux-kernel@...r.kernel.org>,
	<devicetree@...r.kernel.org>
Subject: Re: [PATCH v10 01/14] usb: hcd: Initialize hcd->flags to 0

+Alan,

On 10/06/16 16:07, Roger Quadros wrote:
> When using the OTG/DRD library 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.
> 
> [   91.494257] xhci-hcd xhci-hcd.0.auto: HC died; cleaning up
> [   91.502068] hub 3-0:1.0: state 0 ports 1 chg 0000 evt 0000
> [   91.510240] xhci-hcd xhci-hcd.0.auto: xHCI Host Controller
> [   91.516940] xhci-hcd xhci-hcd.0.auto: new USB bus registered, assigned bus number 4
> [   91.529745] usb usb4: We don't know the algorithms for LPM for this host, disabling LPM.
> [   91.540637] usb usb4: New USB device found, idVendor=1d6b, idProduct=0003
> [   91.757865] irq 254: nobody cared (try booting with the "irqpoll" option)
> [   91.757880] CPU: 0 PID: 68 Comm: kworker/u2:2 Not tainted 4.1.4-00828-g1f0ed8c-dirty #44
> [   91.757885] Hardware name: Generic AM43 (Flattened Device Tree)
> [   91.757914] Workqueue: usb_otg usb_otg_work
> [   91.757921] Backtrace:
> [   91.757954] [<c0012af0>] (dump_backtrace) from [<c0012c8c>] (show_stack+0x18/0x1c)
> [   91.757972]  r6:c089d4a4 r5:ffffffff r4:00000000 r3:ee440000
> [   91.757991] [<c0012c74>] (show_stack) from [<c05f7c14>] (dump_stack+0x84/0xd0)
> [   91.758008] [<c05f7b90>] (dump_stack) from [<c0084b30>] (__report_bad_irq+0x28/0xc8)
> [   91.758024]  r7:00000000 r6:000000fe r5:00000000 r4:ee514c40
> [   91.758037] [<c0084b08>] (__report_bad_irq) from [<c00850b0>] (note_interrupt+0x24c/0x2ac)
> [   91.758052]  r6:000000fe r5:00000000 r4:ee514c40 r3:00000000
> [   91.758065] [<c0084e64>] (note_interrupt) from [<c00828fc>] (handle_irq_event_percpu+0xb0/0x158)
> [   91.758085]  r10:ee514c40 r9:c08ce49a r8:000000fe r7:00000000 r6:00000000 r5:00000000
> [   91.758094]  r4:00000000 r3:00000000
> [   91.758105] [<c008284c>] (handle_irq_event_percpu) from [<c00829e8>] (handle_irq_event+0x44/0x64)
> [   91.758126]  r10:00000001 r9:ee441ab0 r8:ee441bb8 r7:c0858b4c r6:ed174280 r5:ee514ca0
> [   91.758132]  r4:ee514c40
> [   91.758144] [<c00829a4>] (handle_irq_event) from [<c0085970>] (handle_fasteoi_irq+0x100/0x1bc)
> [   91.758159]  r6:c085dba0 r5:ee514ca0 r4:ee514c40 r3:00000000
> [   91.758171] [<c0085870>] (handle_fasteoi_irq) from [<c0082058>] (generic_handle_irq+0x28/0x38)
> [   91.758186]  r7:c0853d40 r6:c0858b4c r5:000000fe r4:000000fe
> [   91.758197] [<c0082030>] (generic_handle_irq) from [<c00821c0>] (__handle_domain_irq+0x98/0x12c)
> [   91.758207]  r4:c0853d40 r3:00000100
> [   91.758219] [<c0082128>] (__handle_domain_irq) from [<c00094e0>] (gic_handle_irq+0x28/0x68)
> [   91.758239]  r10:00000001 r9:ee441bb8 r8:fa240100 r7:c0858d70 r6:ee441ab0 r5:000000b8
> [   91.758245]  r4:fa24010c
> [   91.758264] [<c00094b8>] (gic_handle_irq) from [<c05fd540>] (__irq_svc+0x40/0x74)
> [   91.758271] Exception stack(0xee441ab0 to 0xee441af8)
> [   91.758280] 1aa0:                                     00000000 c08d2980 ee441ac0 00000000
> [   91.758292] 1ac0: 00000008 00000089 c0858b4c c0858080 00000000 ee441bb8 00000001 ee441b3c
> [   91.758301] 1ae0: 00000101 ee441af8 c02fc418 c0046a1c 20000113 ffffffff
> [   91.758321]  r8:00000000 r7:ee441ae4 r6:ffffffff r5:20000113 r4:c0046a1c r3:c02fc418
> [   91.758347] [<c00469a0>] (__do_softirq) from [<c0046eac>] (irq_exit+0xb8/0x104)
> [   91.758367]  r10:00000001 r9:ee441bb8 r8:00000000 r7:c0853d40 r6:c0858b4c r5:00000089
> [   91.758373]  r4:00000000
> [   91.758386] [<c0046df4>] (irq_exit) from [<c00821c8>] (__handle_domain_irq+0xa0/0x12c)
> [   91.758395]  r4:00000000 r3:00000100
> [   91.758406] [<c0082128>] (__handle_domain_irq) from [<c00094e0>] (gic_handle_irq+0x28/0x68)
> [   91.758426]  r10:c08e3510 r9:20000013 r8:fa240100 r7:c0858d70 r6:ee441bb8 r5:00000039
> [   91.758433]  r4:fa24010c
> [   91.758445] [<c00094b8>] (gic_handle_irq) from [<c05fd540>] (__irq_svc+0x40/0x74)
> [   91.758450] Exception stack(0xee441bb8 to 0xee441c00)
> [   91.758457] 1ba0:                                                       00000000 00000001
> [   91.758468] 1bc0: 00000000 ee440000 c08e2524 0000004d 00000274 00000000 00000000 20000013
> [   91.758479] 1be0: c08e3510 ee441c4c ee441b60 ee441c00 c03acfec c0080d4c 60000013 ffffffff
> [   91.758499]  r8:00000000 r7:ee441bec r6:ffffffff r5:60000013 r4:c0080d4c r3:c03acfec
> [   91.758524] [<c0080950>] (console_unlock) from [<c0081670>] (vprintk_emit+0x20c/0x500)
> [   91.758544]  r10:ee441cc0 r9:c08d3550 r8:c08e3ea0 r7:00000000 r6:00000001 r5:0000003d
> [   91.758551]  r4:c08d3550
> [   91.758573] [<c0081464>] (vprintk_emit) from [<c03f6f70>] (dev_vprintk_emit+0x104/0x1ac)
> [   91.758593]  r10:ee441d8c r9:0000000e r8:c07951e0 r7:00000006 r6:ee441cc0 r5:0000000d
> [   91.758599]  r4:ee731068
> [   91.758612] [<c03f6e6c>] (dev_vprintk_emit) from [<c03f7040>] (dev_printk_emit+0x28/0x30)
> [   91.758632]  r10:00000001 r9:ee5f8410 r8:ee731000 r7:ed429000 r6:00000006 r5:ee441dc0
> [   91.758638]  r4:ee731068
> [   91.758651] [<c03f701c>] (dev_printk_emit) from [<c03f7098>] (__dev_printk+0x50/0x70)
> [   91.758660]  r3:bf2268cc r2:c07951e0
> [   91.758673] [<c03f7048>] (__dev_printk) from [<c03f70f4>] (_dev_info+0x3c/0x48)
> [   91.758686]  r6:00000000 r5:ee731068 r4:ee731000
> [   91.758790] [<c03f70bc>] (_dev_info) from [<bf20ec3c>] (usb_new_device+0x11c/0x518 [usbcore])
> [   91.758804]  r3:00000003 r2:00001d6b r1:bf225bc4
> [   91.758881] [<bf20eb20>] (usb_new_device [usbcore]) from [<bf213560>] (usb_otg_add_hcd+0x514/0x7f8 [usbcore])
> [   91.758903]  r10:00000001 r9:ee5f8410 r8:ee731000 r7:000000fe r6:ed4290c8 r5:00000000
> [   91.758909]  r4:ed429000
> [   91.758957] [<bf21304c>] (usb_otg_add_hcd [usbcore]) from [<c047a238>] (usb_otg_start_host+0xb8/0xf8)
> [   91.758978]  r10:00000000 r9:00000002 r8:00000000 r7:ee02b000 r6:ee452808 r5:ee452808
> [   91.758985]  r4:ee452808
> [   91.758997] [<c047a180>] (usb_otg_start_host) from [<c047a020>] (drd_set_protocol+0xac/0xd8)
> [   91.759007]  r4:00000001 r3:c047a180
> [   91.759018] [<c0479f74>] (drd_set_protocol) from [<c047a2ec>] (drd_set_state+0x74/0x98)
> [   91.759027]  r5:ee452808 r4:00000009
> [   91.759039] [<c047a278>] (drd_set_state) from [<c047a3dc>] (usb_otg_work+0xcc/0x154)
> [   91.759054]  r6:ee452808 r5:ee4528b8 r4:ee452968 r3:00000000
> [   91.759072] [<c047a310>] (usb_otg_work) from [<c005754c>] (process_one_work+0x128/0x340)
> [   91.759087]  r6:ee02ac00 r5:ee452968 r4:ee42b900 r3:c047a310
> [   91.759100] [<c0057424>] (process_one_work) from [<c00578f8>] (worker_thread+0x158/0x49c)
> [   91.759120]  r10:ee42b900 r9:00000002 r8:ee02ac00 r7:00000088 r6:ee42b918 r5:ee02ac00
> [   91.759127]  r4:ee02ac14
> [   91.759145] [<c00577a0>] (worker_thread) from [<c005cc40>] (kthread+0xdc/0xf8)
> [   91.759165]  r10:00000000 r9:00000000 r8:00000000 r7:c00577a0 r6:ee42b900 r5:ee429940
> [   91.759174]  r4:00000000 r3:00000000
> [   91.759190] [<c005cb64>] (kthread) from [<c000fc08>] (ret_from_fork+0x14/0x2c)
> [   91.759206]  r7:00000000 r6:00000000 r5:c005cb64 r4:ee429940
> [   91.759209] handlers:
> [   91.759255] [<bf211b5c>] usb_hcd_irq [usbcore]
> [   91.759260] Disabling IRQ #254
> 
> Signed-off-by: Roger Quadros <rogerq@...com>
> Reviewed-by: Peter Chen <peter.chen@....com>
> ---
>  drivers/usb/core/hcd.c | 1 +
>  1 file changed, 1 insertion(+)
> 
> diff --git a/drivers/usb/core/hcd.c b/drivers/usb/core/hcd.c
> index 34b837a..ae6c76d 100644
> --- a/drivers/usb/core/hcd.c
> +++ b/drivers/usb/core/hcd.c
> @@ -3021,6 +3021,7 @@ void usb_remove_hcd(struct usb_hcd *hcd)
>  	}
>  
>  	usb_put_invalidate_rhdev(hcd);
> +	hcd->flags = 0;
>  }
>  EXPORT_SYMBOL_GPL(usb_remove_hcd);
>  
> 

--
cheers,
-roger

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