On Wed, 1 May 2019 at 19:55, Raul E Rangel <rrangel@xxxxxxxxxxxx> wrote: > > There is a race condition between resetting the SDHCI controller and > disconnecting the card. > > For example: > 0) Card is connected and transferring data > 1) mmc_sd_reset is called to reset the controller due to a data error I assume you refer to mmc_sd_hw_reset()? In that case, I think you have interpreted the purpose of mmc_sd_hw_reset() slightly wrong. It's responsibility is to reset the SD-card and not the host/controller. Whether there some additional "reset" of the controller needed, that is assumed by the core, to be managed via the ->set_ios() callback for the host. > 2) sdhci_set_ios calls sdhci_do_reset > 3) SOFT_RESET_ALL is toggled which clears the IRQs the controller has > configured. > 4) Wait for SOFT_RESET_ALL to clear > 5) CD logic notices card is gone and CARD_PRESENT goes low, but since the > IRQs are not configured a CARD_REMOVED interrupt is never raised. > 6) IRQs are enabled again > 7) mmc layer never notices the device is disconnected. The SDHCI layer > will keep returning -ENOMEDIUM. This results in a card that is always > present and not functional. This sounds like host specific problems, which most likely should be fixed in host driver, solely. Unless I am missing something, of course. > > Signed-off-by: Raul E Rangel <rrangel@xxxxxxxxxxxx> > --- > You can see an example of the following two patches here: > https://privatebin.net/?b0f5953716d34ca6#C699bCBQ99NdvspfDW7CMucT8CJG4DgL+yUNPyepDCo= > Line 8213: EILSEQ > Line 8235: SDHC is hard reset > Line 8240: Controller completes reset and card is no longer present > Line 8379: mmc_sd_reset notices card is missing and issues a card_event > and schedules a detect change. > Line 8402: Don't init the card since it's already gone. > Line 8717: Marks card as removed > Line 8820: mmc_sd_remove removes the block device > > I am running into a kernel panic. A task gets stuck for more than 120 > seconds. I keep seeing blkdev_close in the stack trace, so maybe I'm not > calling something correctly? > > Here is the panic: https://privatebin.net/?8ec48c1547d19975#dq/h189w5jmTlbMKKAwZjUr4bhm7Q2AgvGdRqc5BxAc= > > I sometimes see the following: > [ 547.943974] udevd[144]: seq 2350 '/devices/pci0000:00/0000:00:14.7/mmc_host/mmc0/mmc0:0001/block/mmcblk0/mmcblk0p1' is taking a long time > > I was getting the kernel panic on a 4.14 kernel: https://chromium.googlesource.com/chromiumos/third_party/kernel/+/f3dc032faf4d074f20ada437e2d081a28ac699da/drivers/mmc/host > So I'm guessing I'm missing an upstream fix. > > Do the patches look correct or am I doing something that would cause a > kernel panic? > > I have a DUT setup with a GPIO I can use to toggle the CD pin. I ran a > test where I connect and then randomly, between 0s - 1s disconnect the > card. This got over 20k iterations before the panic. Though when I do it > manually and stop for 2 minutes the panic happens. > > Any help would be appreciated. > > Thanks, > Raul > > > drivers/mmc/core/sd.c | 20 ++++++++++++++++++++ > 1 file changed, 20 insertions(+) > > diff --git a/drivers/mmc/core/sd.c b/drivers/mmc/core/sd.c > index 265e1aeeb9d8..9206c4297d66 100644 > --- a/drivers/mmc/core/sd.c > +++ b/drivers/mmc/core/sd.c > @@ -1242,7 +1242,27 @@ static int mmc_sd_runtime_resume(struct mmc_host *host) > > static int mmc_sd_hw_reset(struct mmc_host *host) > { > + int present; > mmc_power_cycle(host, host->card->ocr); > + > + present = host->ops->get_cd(host); > + > + /* The card status could have changed while resetting. */ > + if ((mmc_card_removed(host->card) && present) || > + (!mmc_card_removed(host->card) && !present)) { > + pr_info("%s: card status changed during reset\n", > + mmc_hostname(host)); > + host->ops->card_event(host); > + mmc_detect_change(host, 0); > + } > + > + /* Don't perform unnecessary transactions if the card is missing. */ > + if (!present) { > + pr_info("%s: card was removed during reset\n", > + mmc_hostname(host)); > + return -ENOMEDIUM; > + } > + When doing a mmc_hw_reset() (which ends up calling mmc_sd_hw_reset() in case of SD cards), we are making a final attempt to make the card functional again, via a power cycle and a re-init of it. In this path, we don't care whether the card is removed, as that should have been detected already when the block layer calls mmc_detect_card_removed(). > return mmc_sd_init_card(host, host->card->ocr, host->card); > } > > -- > 2.21.0.593.g511ec345e18-goog > Kind regards Uffe
