Re: armmmci rmmod causes hung tasks

[Martin DEVERA]

On 11/30/20 4:08 PM, Ulf Hansson wrote:
> On Sun, 29 Nov 2020 at 19:20, Martin DEVERA <devik@xxxxxxxxxx> wrote:
> > Hello,
> >
> > on STM32MP1 with almost vanilla 5.7.7 in single CPU mode. Pair of
> > modprobe armmmci ; rmmod armmmci
> >
> > causes rmmod and kworker to hang. I should note that no MMC is detected
> > on the board (SDIO device on MMC bus is not responding).
> > On another board (where SDIO is responding) rmmod works.
> >
> > It seems as another manifestation of https://lkml.org/lkml/2019/8/27/945
> >
> > Thanks.
> >
> > INFO: task kworker/0:1:12 blocked for more than 368 seconds.
> >         Not tainted 5.7.7kdb-00003-g10397828596c-dirty #224
> > "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
> > kworker/0:1     D    0    12      2 0x00000000
> > Workqueue: events_freezable mmc_rescan
> > (__schedule) from (schedule+0x5b/0x90)
> > (schedule) from (schedule_timeout+0x1b/0xa0)
> > (schedule_timeout) from (__wait_for_common+0x7d/0xdc)
> > (__wait_for_common) from (mmc_wait_for_req_done+0x1b/0x8c)
> > (mmc_wait_for_req_done) from (mmc_wait_for_cmd+0x4d/0x68)
> > (mmc_wait_for_cmd) from (mmc_io_rw_direct_host+0x87/0xc8)
> > (mmc_io_rw_direct_host) from (sdio_reset+0x3b/0x58)
> > (sdio_reset) from (mmc_rescan+0x15d/0x1d4)
> > (mmc_rescan) from (process_one_work+0xdd/0x168)
> > (process_one_work) from (worker_thread+0x17d/0x1ec)
> > (worker_thread) from (kthread+0x9b/0xa4)
> > (kthread) from (ret_from_fork+0x11/0x28)
> It looks like the worker thread, which runs mmc_rescan() to try to
> detect the SDIO card is hanging. Exactly why, I don't know.
>
> Could be a misconfigured clock, pinctrl or a power domain being
> suddenly gated...

I turned some logging on (see below), IIUC pl18x is starting CMD52 with arg
SDIO_CCCR_ABORT read and it got IRQ later along with response. Then sending
again SDIO_CCCR_ABORT write but no IRQ comes back.

[  135.810802] mmc0: mmc_rescan_try_freq: trying to init card at 400000 Hz
[  135.810832] mmc0: starting CMD52 arg 00000c00 flags 00000195
[  135.810862] mmci-pl18x 48004000.sdmmc: op 34 arg 00000c00 flags 00000195
[  135.811155] mmci-pl18x 48004000.sdmmc: irq0 (data+cmd) 00000040
[  135.811178] mmc0: req done (CMD52): 0: 00000000 00000000 00000000 
00000000
[  135.811202] mmci-pl18x 48004000.sdmmc: irq0 (data+cmd) 00000000
[  135.816487] mmc0: starting CMD52 arg 80000c08 flags 00000195
[  135.816506] mmci-pl18x 48004000.sdmmc: op 34 arg 80000c08 flags 00000195
[  172.150614] random: crng init done
[  172.150642] random: 6 urandom warning(s) missed due to ratelimiting
[  173.290565] INFO: task kworker/0:0:5 blocked for more than 20 seconds.

Here is the same system, only with different (working) SDIO device on 
the same bus:

[  495.654596] mmc0: mmc_rescan_try_freq: trying to init card at 400000 Hz
[  495.654628] mmc0: starting CMD52 arg 00000c00 flags 00000195
[  495.654658] mmci-pl18x 48004000.sdmmc: op 34 arg 00000c00 flags 00000195
[  495.654996] mmci-pl18x 48004000.sdmmc: irq0 (data+cmd) 00000004
[  495.655017] mmc0: req done (CMD52): -110: 00000000 00000000 00000000 
00000000
[  495.655042] mmci-pl18x 48004000.sdmmc: irq0 (data+cmd) 00000000
[  495.660201] mmc0: starting CMD52 arg 80000c08 flags 00000195
[  495.660222] mmci-pl18x 48004000.sdmmc: op 34 arg 80000c08 flags 00000195
[  495.660549] mmci-pl18x 48004000.sdmmc: irq0 (data+cmd) 00000004
[  495.660567] mmc0: req done (CMD52): -110: 00000000 00000000 00000000 
00000000
[  495.660591] mmci-pl18x 48004000.sdmmc: irq0 (data+cmd) 00000000

Should it be expected, that invalid (probably non-responding) device on 
the SDIO bus
causes it to be locked up forever ?
Or is it bug in pl18x driver not handling the error correctly ?

best regards,
Martin