Messages in this thread | | | From | Andy Shevchenko <> | Date | Fri, 9 Jul 2021 18:45:06 +0300 | Subject | Re: parallel panel display stopped working |
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On Fri, Jul 9, 2021 at 5:54 PM Andy Shevchenko <andy.shevchenko@gmail.com> wrote: > > On Fri, Jul 9, 2021 at 5:40 PM Andy Shevchenko > <andy.shevchenko@gmail.com> wrote: > > > > Parallel (4 bits) panel display stopped working. > > I have no time right now to bisect but I have noticed there was quite > > a pile of patches from Lars to the driver recently (yeah, it seems for > > a few months I haven't run my tests against the AUX display driver). > > > > I believe the issue is there somewhere. > > > > Moreover on the removal I have got an oops > > > > [ 218.825445] kernel tried to execute NX-protected page - exploit > > attempt? (uid: 0) > > [ 218.832965] BUG: unable to handle page fault for address: ffff8f8f06559dc0 > > [ 218.839863] #PF: supervisor instruction fetch in kernel mode > > [ 218.845540] #PF: error_code(0x0011) - permissions violation > > [ 218.851132] PGD e601067 P4D e601067 PUD e602067 PMD 645a063 PTE > > 8000000006559063 > > [ 218.858587] Oops: 0011 [#1] SMP PTI > > [ 218.862099] CPU: 0 PID: 7 Comm: kworker/u4:0 Tainted: G C > > 5.13.0+ #23 > > [ 218.869870] Hardware name: Intel Corporation Merrifield/BODEGA BAY, > > BIOS 542 2015.01.21:18.19.48 > > [ 218.878681] Workqueue: kacpi_hotplug acpi_device_del_work_fn > > [ 218.884380] RIP: 0010:0xffff8f8f06559dc0 > > [ 218.888328] Code: ff ff d2 2b 21 8c ff ff ff ff 08 00 00 00 00 00 > > 00 00 78 34 fa 02 8f 8f ff ff 00 00 00 00 00 > > 00 00 00 00 00 00 00 00 00 00 00 <72> 65 67 75 6c 61 74 6f 72 3a 72 65 > > 67 75 6c 61 74 6f 72 2e 30 2d > > [ 218.907138] RSP: 0000:ffffad36c0043c90 EFLAGS: 00010246 > > [ 218.912387] RAX: ffff8f8f06559dc0 RBX: ffff8f8f062cbc00 RCX: ffff8f8f01239fc8 > > [ 218.919542] RDX: 000000002a3cccf8 RSI: 0000000000000001 RDI: ffff8f8f06559480 > > [ 218.926701] RBP: ffffffffc037e279 R08: 00000000d5832520 R09: 0000000000000001 > > [ 218.933856] R10: 0000000000000000 R11: 0000000000000001 R12: ffff8f8f062cbc00 > > [ 218.941010] R13: ffffffffc038e028 R14: ffffffff8c5e0b60 R15: 00000000fffffffd > > [ 218.948166] FS: 0000000000000000(0000) GS:ffff8f8f3e200000(0000) > > knlGS:0000000000000000 > > [ 218.956286] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 > > [ 218.962053] CR2: ffff8f8f06559dc0 CR3: 0000000002ef4000 CR4: 00000000001006f0 > > [ 218.969208] Call Trace: > > [ 218.971678] ? hd44780_common_clear_display+0x17/0x30 [hd44780_common] > > [ 218.978252] ? charlcd_write_char+0x21a/0x810 [charlcd] > > [ 218.983519] ? charlcd_puts+0x30/0x60 [charlcd] > > [ 218.988083] ? charlcd_unregister+0x24/0x70 [charlcd] > > [ 218.993167] ? hd44780_remove+0x1e/0x30 [hd44780] > > [ 218.997901] ? platform_remove+0x1f/0x40 > > ... > > > > Just for your information and with hope that somebody may test and/or > > reproduce this and fix it. Later on I might find time to bisect the > > other issue I mentioned above. > > For time being confirmed the following: > 1. a2060f288e15 ("auxdisplay: Call charlcd_backlight in place") has a > remove bug (above), while panel works > 2. 66ce7d5c1e12 ("auxdisplay: Use an enum for charlcd backlight on/off > ops") everything works as expected > > So, the oops introduced in between those two.
The culprit (*) is 01ec46dfa633 ("auxdisplay: Move init_display to hd44780_common").
*) Obviously it's not. It reveals the design issue on how the modules were split. How this had been tested if tested at all?
P.S. If we don't get a fix in time, I will ask Miguel to revert the entire pile.
-- With Best Regards, Andy Shevchenko
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