linux-toradex.git/drivers/mmc/host, branch v4.10

mmc: mmci: avoid clearing ST Micro busy end interrupt mistakenly

2017-02-08T11:22:27+00:00

This fixes a race condition that may occur whenever ST micro busy end
interrupt is raised just after being unmasked but before leaving mmci
interrupt context.

A dead-lock has been found if connecting mmci ST Micro variant whose amba
id is 0x10480180 to some new eMMC that supports internal caches.  Whenever
mmci driver enables cache control by programming eMMC's EXT_CSD register,
block driver may request to flush the eMMC internal caches causing mmci
driver to send a MMC_SWITCH command to the card with FLUSH_CACHE operation.
And because busy end interrupt may be mistakenly cleared while not yet
processed, this mmc request may never complete.  As a result, mmcqd task
may be stuck forever.

Here is an instance caught by lockup detector which shows that mmcqd task
was hung while waiting for mmc_flush_cache command to complete:

..
[  240.251595] INFO: task mmcqd/1:52 blocked for more than 120 seconds.
[  240.257973]       Not tainted 4.1.13-00510-g9d91424 #2
[  240.263109] "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
[  240.270955] mmcqd/1         D c047504c     0    52      2 0x00000000
[  240.277359] [] (__schedule) from [] (schedule+0x40/0x98)
[  240.284418] [] (schedule) from [] (schedule_timeout+0x148/0x188)
[  240.292191] [] (schedule_timeout) from [] (wait_for_common+0xa4/0x170)
[  240.300491] [] (wait_for_common) from [] (mmc_wait_for_req_done+0x4c/0x13c)
[  240.309224] [] (mmc_wait_for_req_done) from [] (mmc_wait_for_cmd+0x64/0x84)
[  240.317953] [] (mmc_wait_for_cmd) from [] (__mmc_switch+0xa4/0x2a8)
[  240.325964] [] (__mmc_switch) from [] (mmc_switch+0x28/0x30)
[  240.333389] [] (mmc_switch) from [] (mmc_flush_cache+0x54/0x80)
[  240.341073] [] (mmc_flush_cache) from [] (mmc_blk_issue_rq+0x114/0x4e8)
[  240.349459] [] (mmc_blk_issue_rq) from [] (mmc_queue_thread+0xc0/0x180)
[  240.357844] [] (mmc_queue_thread) from [] (kthread+0xdc/0xf4)
[  240.365339] [] (kthread) from [] (ret_from_fork+0x14/0x2c)
..
..
[  240.664311] INFO: task partprobe:564 blocked for more than 120 seconds.
[  240.670943]       Not tainted 4.1.13-00510-g9d91424 #2
[  240.676078] "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
[  240.683922] partprobe       D c047504c     0   564    486 0x00000000
[  240.690318] [] (__schedule) from [] (schedule+0x40/0x98)
[  240.697396] [] (schedule) from [] (schedule_timeout+0x148/0x188)
[  240.705149] [] (schedule_timeout) from [] (wait_for_common+0xa4/0x170)
[  240.713446] [] (wait_for_common) from [] (submit_bio_wait+0x58/0x64)
[  240.721571] [] (submit_bio_wait) from [] (blkdev_issue_flush+0x60/0x88)
[  240.729957] [] (blkdev_issue_flush) from [] (blkdev_fsync+0x34/0x44)
[  240.738083] [] (blkdev_fsync) from [] (do_fsync+0x3c/0x64)
[  240.745319] [] (do_fsync) from [] (ret_fast_syscall+0x0/0x3c)
..

Here is the detailed sequence showing when this issue may happen:

1) At probe time, mmci device is initialized and card busy detection based
on DAT[0] monitoring is enabled.

2) Later during run time, since card reported to support internal caches, a
MMCI_SWITCH command is sent to eMMC device with FLUSH_CACHE operation. On
receiving this command, eMMC may enter busy state (for a relatively short
time in the case of the dead-lock).

3) Then mmci interrupt is raised and mmci_irq() is called:

MMCISTATUS register is read and is equal to 0x01000440. So the following
status bits are set:
- MCI_CMDRESPEND (= 6)
- MCI_DATABLOCKEND (= 10)
- MCI_ST_CARDBUSY (= 24)

Since MMCIMASK0 register is 0x3FF, status variable is set to 0x00000040 and
BIT MCI_CMDRESPEND is cleared by writing MMCICLEAR register.

Then mmci_cmd_irq() is called. Considering the following conditions:
- host->busy_status is 0,
- this is a "busy response",
- reading again MMCISTATUS register gives 0x1000400,
MMCIMASK0 is updated to unmask MCI_ST_BUSYEND bit.

Thus, MMCIMASK0 is set to 0x010003FF and host->busy_status is set to wait
for busy end completion.

Back again in status loop of mmci_irq(), we quickly go through
mmci_data_irq() as there are no data in that case.  And we finally go
through following test at the end of while(status) loop:

/*
 * Don't poll for busy completion in irq context.
 */
if (host->variant->busy_detect && host->busy_status)
	status &= ~host->variant->busy_detect_flag;

Because status variable is not yet null (is equal to 0x40), we do not leave
interrupt context yet but we loop again into while(status) loop. So we run
across following steps:

a) MMCISTATUS register is read again and this time is equal to 0x01000400.
So that following bits are set:
- MCI_DATABLOCKEND (= 10)
- MCI_ST_CARDBUSY (= 24)

Since MMCIMASK0 register is equal to 0x010003FF:

b) status variable is set to 0x01000000.
c) MCI_ST_CARDBUSY bit is cleared by writing MMCICLEAR register.

Then, mmci_cmd_irq() is called one more time. Since host->busy_status is
set and that MCI_ST_CARDBUSY is set in status variable, we just return from
this function.

Back again in mmci_irq(), status variable is set to 0 and we finally leave
the while(status) loop. As a result we leave interrupt context, waiting for
busy end interrupt event.

Now, consider that busy end completion is raised IN BETWEEN steps 3.a) and
3.c). In such a case, we may mistakenly clear busy end interrupt at step
3.c) while it has not yet been processed. This will result in mmc command
to wait forever for a busy end completion that will never happen.

To fix the problem, this patch implements the following changes:

Considering that the mmci seems to be triggering the IRQ on both edges
while monitoring DAT0 for busy completion and that same status bit is used
to monitor start and end of busy detection, special care must be taken to
make sure that both start and end interrupts are always cleared one after
the other.

1) Clearing of card busy bit is moved in mmc_cmd_irq() function where
unmasking of busy end bit is effectively handled.
2) Just before unmasking busy end event, busy start event is cleared by
writing card busy bit in MMCICLEAR register.
3) Finally, once we are no more busy with a command, busy end event is
cleared writing again card busy bit in MMCICLEAR register.

This patch has been tested with the ST Accordo5 machine, not yet supported
upstream but relies on the mmci driver.

Signed-off-by: Sarang Mairal 
Signed-off-by: Jean-Nicolas Graux 
Reviewed-by: Linus Walleij 
Tested-by: Ulf Hansson 
Signed-off-by: Ulf Hansson

mmc: sdhci: Ignore unexpected CARD_INT interrupts

2017-01-31T10:26:49+00:00

One of our kernelCI boxes hanged at boot because a faulty eSDHC device
was triggering spurious CARD_INT interrupts for SD cards, causing CMD52
reads, which are not allowed for SD devices.  This adds a sanity check
to the interruption path, preventing that illegal command from getting
sent if the CARD_INT interruption should be disabled.

This quirk allows that particular machine to resume boot despite the
faulty hardware, instead of getting hung dealing with thousands of
mishandled interrupts.

Suggested-by: Adrian Hunter 
Signed-off-by: Gabriel Krisman Bertazi 
Acked-by: Adrian Hunter 
Signed-off-by: Ulf Hansson 
Cc:

mmc: dw_mmc: force setup bus if active slots exist

2017-01-23T09:19:30+00:00

It's necessary to setup bus if any slots are present.
- update clock after ctrl reset
- if the host has genpd node, we can guarantee the clock is
  available before starting request. Otherwies, the clock register
  is reset once power off the pd, and host can't output the active
  clock during communication.

Fixes: e9ed8835e990 ("mmc: dw_mmc: add runtime PM callback")
Fixes: df9bcc2bc0a1 ("mmc: dw_mmc: add missing codes for runtime resume")
cc: 
Reported-by: Randy Li 
Reported-by: S. Gilles 
Signed-off-by: Ziyuan Xu 
Signed-off-by: Shawn Lin 
Signed-off-by: Ulf Hansson

mmc: mxs-mmc: Fix additional cycles after transmission stop

2017-01-12T11:31:00+00:00

According to the code the intention is to append 8 SCK cycles
instead of 4 at end of a MMC_STOP_TRANSMISSION command. But this
will never happened because it's an AC command not an ADTC command.
So fix this by moving the statement into the right function.

Signed-off-by: Stefan Wahren 
Fixes: e4243f13d10e (mmc: mxs-mmc: add mmc host driver for i.MX23/28)
Cc: 
Signed-off-by: Ulf Hansson

mmc: sdhci-acpi: Only powered up enabled acpi child devices

2017-01-12T11:15:20+00:00

Commit e5bbf30733f9 ("mmc: sdhci-acpi: Ensure connected devices are
powered when probing") introduced code to powerup any acpi child
nodes listed in the dstd. But some dstd-s list all possible devices
used on some board variants, while reporting if the device is actually
present and enabled in the status field of the device.

So we end up calling the acpi _PS0 (power-on) method for devices which
are not actually present. This does not always end well, e.g. on my
cube iwork8 air tablet, this results in freezing the entire tablet as
soon as the r8723bs module is loaded.

This commit fixes this by checking the child device's status.present
and status.enabled bits and only call acpi_device_fix_up_power()
if both are set.

Fixes: e5bbf30733f9 ("mmc: sdhci-acpi: Ensure connected devices are powered when probing")
BugLink: https://github.com/hadess/rtl8723bs/issues/80
Signed-off-by: Hans de Goede 
Acked-by: Adrian Hunter 
Cc: 
Signed-off-by: Ulf Hansson

MMC: meson: avoid possible NULL dereference

2017-01-10T10:53:00+00:00

No actual segmentation faults were observed but the coding is
at least inconsistent.

irqreturn_t meson_mmc_irq():

We should not dereference host before checking it.

meson_mmc_irq_thread():

If cmd or mrq are NULL we should not dereference them after
writing a warning.

Fixes: 51c5d8447bd7 MMC: meson: initial support for GX platforms
Signed-off-by: Heinrich Schuchardt 
Acked-by: Kevin Hilman 
Signed-off-by: Ulf Hansson

Replace with globally

2016-12-24T19:46:01+00:00

This was entirely automated, using the script by Al:

  PATT='^[[:blank:]]*#[[:blank:]]*include[[:blank:]]*'
  sed -i -e "s!$PATT!#include !" \
        $(git grep -l "$PATT"|grep -v ^include/linux/uaccess.h)

to do the replacement at the end of the merge window.

Requested-by: Al Viro 
Signed-off-by: Linus Torvalds

mmc: sdhci: Fix to handle MMC_POWER_UNDEFINED

2016-12-20T10:42:33+00:00

Since commit c2c24819b280 ("mmc: core: Don't power off the card when
starting the host"), the power state can still be MMC_POWER_UNDEFINED after
mmc_start_host() is called. That can trigger a warning in SDHCI during
runtime resume as it tries to restore the I/O state. Handle
MMC_POWER_UNDEFINED simply by not updating the I/O state in that case.

Fixes: c2c24819b280 ("mmc: core: Don't power off the card when starting the host")
Signed-off-by: Adrian Hunter 
Signed-off-by: Ulf Hansson

mmc: sdhci-cadence: add Socionext UniPhier specific compatible string

2016-12-20T10:40:52+00:00

Add a Socionext SoC specific compatible (suggested by Rob Herring).

No SoC specific data are associated with the compatible strings for
now, but other SoC vendors may use this IP and want to differentiate
IP variants in the future.

Signed-off-by: Masahiro Yamada 
Acked-by: Rob Herring 
Signed-off-by: Ulf Hansson

mmc: sdhci-cadence: add Cadence SD4HC support

2016-12-08T14:02:52+00:00

Add a driver for the Cadence SD4HC SD/SDIO/eMMC Controller.

For SD, it basically relies on the SDHCI standard code.
For eMMC, this driver provides some callbacks to support the
hardware part that is specific to this IP design.

Signed-off-by: Masahiro Yamada 
Acked-by: Adrian Hunter 
Signed-off-by: Ulf Hansson