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.
What the log in the series does not tell is the driver was initially built around a supposed issue with the thermal sensor, that is multiple interrupts firing for the same event.
Those happen when a specific threshold is reached (down to up and up to down) and a hysteresis should have been specified in the register in order to prevent multiple interrupts firing when the limit is crossed.
All the code in the driver was built to overcome this issue because the root cause was not spotted: the hysteresis register was not correctly set and it was reset at every update. The driver 'workarounded' that by creating some kind of irq enabled flag, a sensor reset every time it was read and other hacks to make it work (it results in a worst temperature measurement accuracy also because the temperature buffer on the chip is flushed).
These 5 patches not only fixes the irq issue but also sanitize the driver. There is no longer a reset of the sensor, no irq bouncing and no 5ms delay when the sensor is read.