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Date:   Mon, 3 Dec 2018 19:05:21 +0100
From:   Greg KH <gregkh@linuxfoundation.org>
To:     Sasha Levin <sashal@kernel.org>
Cc:     Daniel Lezcano <daniel.lezcano@linaro.org>,
        Rafael David Tinoco <rafael.tinoco@linaro.org>,
        rui.zhang@intel.com, edubezval@gmail.com, linux-pm@vger.kernel.org,
        linux-kernel@vger.kernel.org, stable@vger.kernel.org
Subject: Re: v4.14 fix for Hikey 960 unbalanced IRQ enablement
Message-ID: <20181203180521.GA15996@kroah.com>
References: <20181203133107.4002-1-rafael.tinoco@linaro.org>
 <20181203141442.GA19335@kroah.com>
 <dc468512-7a73-3d69-fe9e-d660db85ee5b@linaro.org>
 <20181203151946.GG235790@sasha-vm>
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In-Reply-To: <20181203151946.GG235790@sasha-vm>
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Sender: linux-kernel-owner@vger.kernel.org
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On Mon, Dec 03, 2018 at 10:19:46AM -0500, Sasha Levin wrote:
> On Mon, Dec 03, 2018 at 03:42:41PM +0100, Daniel Lezcano wrote:
> > On 03/12/2018 15:14, Greg KH wrote:
> > > On Mon, Dec 03, 2018 at 11:31:02AM -0200, Rafael David Tinoco wrote:
> > > > Sasha, could you consider including this cherry-picked patchset in v4.14.
> > > > 
> > > > Kernel v4.14 might suffer from the following unbalanced enablement for the board Hikey 960:
> > > > 
> > > > Nov  5 12:02:54 hikey kernel: [   22.148194] Unbalanced enable for IRQ 44
> > > > Nov  5 12:02:54 hikey kernel: [   22.152193] ------------[ cut here ]------------
> > > > Nov  5 12:02:54 hikey kernel: [   22.156872] WARNING: CPU: 2 PID: 509 at /home/inaddy/work/sources/linux/stable/stable-linux-4.14.y/kernel/irq/manage.c:525 __enable_irq+0x78/0x80
> > > > Nov  5 12:02:54 hikey kernel: [   22.249606] CPU: 2 PID: 509 Comm: kworker/2:2 Not tainted 4.14.79 #1
> > > > Nov  5 12:02:54 hikey kernel: [   22.255975] Hardware name: HiKey Development Board (DT)
> > > > Nov  5 12:02:54 hikey kernel: [   22.261248] Workqueue: events_freezable thermal_zone_device_check
> > > > Nov  5 12:02:54 hikey kernel: [   22.267368] task: ffff8000616e0e00 task.stack: ffff00000b5f0000
> > > > Nov  5 12:02:54 hikey kernel: [   22.273312] PC is at __enable_irq+0x78/0x80
> > > > Nov  5 12:02:54 hikey kernel: [   22.277516] LR is at __enable_irq+0x78/0x80
> > > > Nov  5 12:02:54 hikey kernel: [   22.281718] pc : [<ffff00000813e010>] lr : [<ffff00000813e010>] pstate: 000001c5
> > > > Nov  5 12:02:54 hikey kernel: [   22.289129] sp : ffff00000b5f3c80
> > > > Nov  5 12:02:54 hikey kernel: [   22.292457] x29: ffff00000b5f3c80 x28: 0000000000000000
> > > > Nov  5 12:02:54 hikey kernel: [   22.297804] x27: ffff80005c139e38 x26: ffff000008a71870
> > > > Nov  5 12:02:54 hikey kernel: [   22.303148] x25: 0000000000000000 x24: 0000000000000002
> > > > Nov  5 12:02:54 hikey kernel: [   22.308492] x23: ffff00000b5f3d9c x22: ffff80005d565e88
> > > > Nov  5 12:02:54 hikey kernel: [   22.313836] x21: 000000000000f980 x20: 000000000000002c
> > > > Nov  5 12:02:54 hikey kernel: [   22.319181] x19: ffff800061726000 x18: 0000000000000010
> > > > Nov  5 12:02:54 hikey kernel: [   22.324524] x17: 0000000000000000 x16: 0000000000000000
> > > > Nov  5 12:02:54 hikey kernel: [   22.329868] x15: ffffffffffffffff x14: ffff000009269c08
> > > > Nov  5 12:02:54 hikey kernel: [   22.335213] x13: ffff00008940678f x12: ffff000009406797
> > > > Nov  5 12:02:54 hikey kernel: [   22.340558] x11: ffff000009290000 x10: ffff00000b5f3980
> > > > Nov  5 12:02:54 hikey kernel: [   22.345902] x9 : 00000000ffffffd0 x8 : ffff00000862c298
> > > > Nov  5 12:02:54 hikey kernel: [   22.351246] x7 : 6c62616e65206465 x6 : 00000000000001b2
> > > > Nov  5 12:02:54 hikey kernel: [   22.356589] x5 : 0000000000000000 x4 : 0000000000000000
> > > > Nov  5 12:02:54 hikey kernel: [   22.361931] x3 : 0000000000000000 x2 : ffff800063e824c8
> > > > Nov  5 12:02:54 hikey kernel: [   22.367275] x1 : 000080005af95000 x0 : 000000000000001c
> > > > Nov  5 12:02:54 hikey kernel: [   22.372618] Call trace:
> > > > Nov  5 12:02:54 hikey kernel: [   22.375088] Exception stack(0xffff00000b5f3b40 to 0xffff00000b5f3c80)
> > > > Nov  5 12:02:54 hikey kernel: [   22.381560] 3b40: 000000000000001c 000080005af95000 ffff800063e824c8 0000000000000000
> > > > Nov  5 12:02:54 hikey kernel: [   22.389417] 3b60: 0000000000000000 0000000000000000 00000000000001b2 6c62616e65206465
> > > > Nov  5 12:02:54 hikey kernel: [   22.397276] 3b80: ffff00000862c298 00000000ffffffd0 ffff00000b5f3980 ffff000009290000
> > > > Nov  5 12:02:54 hikey kernel: [   22.405136] 3ba0: ffff000009406797 ffff00008940678f ffff000009269c08 ffffffffffffffff
> > > > Nov  5 12:02:54 hikey kernel: [   22.412994] 3bc0: 0000000000000000 0000000000000000 0000000000000010 ffff800061726000
> > > > Nov  5 12:02:54 hikey kernel: [   22.420852] 3be0: 000000000000002c 000000000000f980 ffff80005d565e88 ffff00000b5f3d9c
> > > > Nov  5 12:02:54 hikey kernel: [   22.428710] 3c00: 0000000000000002 0000000000000000 ffff000008a71870 ffff80005c139e38
> > > > Nov  5 12:02:54 hikey kernel: [   22.436569] 3c20: 0000000000000000 ffff00000b5f3c80 ffff00000813e010 ffff00000b5f3c80
> > > > Nov  5 12:02:54 hikey kernel: [   22.444426] 3c40: ffff00000813e010 00000000000001c5 0000000000000000 0000000000000000
> > > > Nov  5 12:02:54 hikey kernel: [   22.452286] 3c60: ffffffffffffffff ffff800061800618 ffff00000b5f3c80 ffff00000813e010
> > > > Nov  5 12:02:54 hikey kernel: [   22.460144] [<ffff00000813e010>] __enable_irq+0x78/0x80
> > > > Nov  5 12:02:54 hikey kernel: [   22.465394] [<ffff00000813e058>] enable_irq+0x40/0x78
> > > > Nov  5 12:02:54 hikey kernel: [   22.470493] [<ffff000000e228a8>] hisi_thermal_get_temp+0x1b0/0x1d8 [hisi_thermal]
> > > > Nov  5 12:02:54 hikey kernel: [   22.478008] [<ffff0000087121a8>] of_thermal_get_temp+0x38/0x50
> > > > Nov  5 12:02:54 hikey kernel: [   22.483869] [<ffff000008711790>] thermal_zone_get_temp+0x58/0x80
> > > > Nov  5 12:02:54 hikey kernel: [   22.489903] [<ffff00000870e7bc>] thermal_zone_device_update.part.4+0x2c/0x1a8
> > > > Nov  5 12:02:54 hikey kernel: [   22.497066] [<ffff00000870e9c8>] thermal_zone_device_check+0x40/0x50
> > > > Nov  5 12:02:54 hikey kernel: [   22.503457] [<ffff0000080f1674>] process_one_work+0x19c/0x3d0
> > > > Nov  5 12:02:54 hikey kernel: [   22.509236] [<ffff0000080f18f4>] worker_thread+0x4c/0x428
> > > > Nov  5 12:02:54 hikey kernel: [   22.514664] [<ffff0000080f84fc>] kthread+0x134/0x138
> > > > Nov  5 12:02:54 hikey kernel: [   22.519659] [<ffff000008085154>] ret_from_fork+0x10/0x1c
> > > > Nov  5 12:02:54 hikey kernel: [   22.524988] ---[ end trace 328d4bb2d9b066a0 ]---
> > > > 
> > > > This issue was solved when "hisi_thermal_alarm_irq" function was removed so only
> > > > "hisi_thermal_alarm_irq_thread" would exist. This has fixed the issue for the
> > > > unbalanced enablement since there is no more:
> > > > 
> > > > 	disable_irq_nosync(irq);
> > > > 	data->irq_enabled = false;
> > > > 
> > > > logic being done in parallel to the threaded handler AND the
> > > > thermal_zone_device_update() call only happens now if the temperature is already
> > > > above the threshold.
> > > > 
> > > 
> > > So should we revert a patch instead of taking these new ones?  Would
> > > that be easier and is this a "real" issue or just an annoying warning
> > > splat in the kernel log?
> > 
> > Actually, this warning is introduced with the driver and all the
> > plumbers around to fix an irq bouncing. There is no patch to revert
> > without removing the driver.
> 
> Greg,
> 
> Patch 5 in this series seems to explain the best what is happening here:
> 
> > With the following changes, we fix all in one:
> > 
> > - Do the setup, one time, at probe time
> > 
> > - Add the IRQF_ONESHOT, ack the interrupt in the threaded handler
> > 
> > - Remove the interrupt handler
> > 
> > - Set the correct value for the LAG register
> > 
> > - Remove all the irq_enabled stuff in the code as the interruption
> >   handling is fixed
> > 
> > - Remove the 3ms delay
> > 
> > - Reorder the initialization routine to be in the right order
> 
> We can't revert anything because the breakage was there since the driver
> was introduced.

So the driver was broken in 4.14, why not just use 4.19 instead?  This
isn't a 4.14 regression, it's something that obviously no one has
noticed for a year now, so why backport these big patches to 4.14 now?

thanks,

greg k-h