linux-toradex.git/drivers/tty/serial/qcom_geni_serial.c, branch v6.4-rc6

serial: qcom-geni: fix enabling deactivated interrupt

2023-05-13T11:00:54+00:00

The driver have a race, experienced only with PREEMPT_RT patchset:

CPU0                         | CPU1
==================================================================
qcom_geni_serial_probe       |
  uart_add_one_port          |
                             | serdev_drv_probe
                             |   qca_serdev_probe
                             |     serdev_device_open
                             |       uart_open
                             |         uart_startup
                             |           qcom_geni_serial_startup
                             |             enable_irq
                             |               __irq_startup
                             |                 WARN_ON()
                             |                 IRQ not activated
  request_threaded_irq       |
    irq_domain_activate_irq  |

The warning:

  894000.serial: ttyHS1 at MMIO 0x894000 (irq = 144, base_baud = 0) is a MSM
  serial serial0: tty port ttyHS1 registered
  WARNING: CPU: 7 PID: 107 at kernel/irq/chip.c:241 __irq_startup+0x78/0xd8
  ...
  qcom_geni_serial 894000.serial: serial engine reports 0 RX bytes in!

Adding UART port triggers probe of child serial devices - serdev and
eventually Qualcomm Bluetooth hci_qca driver.  This opens UART port
which enables the interrupt before it got activated in
request_threaded_irq().  The issue originates in commit f3974413cf02
("tty: serial: qcom_geni_serial: Wakeup IRQ cleanup") and discussion on
mailing list [1].  However the above commit does not explain why the
uart_add_one_port() is moved above requesting interrupt.

[1] https://lore.kernel.org/all/5d9f3dfa.1c69fb81.84c4b.30bf@mx.google.com/

Fixes: f3974413cf02 ("tty: serial: qcom_geni_serial: Wakeup IRQ cleanup")
Cc: 
Cc: Stephen Boyd 
Signed-off-by: Krzysztof Kozlowski 
Reviewed-by: Stephen Boyd 
Link: https://lore.kernel.org/r/20230505152301.2181270-1-krzysztof.kozlowski@linaro.org
Signed-off-by: Greg Kroah-Hartman

tty: serial: simplify qcom_geni_serial_send_chunk_fifo()

2023-04-20T11:32:51+00:00

* use memcpy() instead of the loop (removes c variable)
* use remaining parameter directly (removes chunk variable)

The code is simpler and easier to follow.

Cc: Andy Gross 
Cc: Bjorn Andersson 
Cc: Konrad Dybcio 
Cc: linux-arm-msm@vger.kernel.org
Signed-off-by: Jiri Slaby (SUSE) 
Link: https://lore.kernel.org/r/20230420093514.13055-1-jirislaby@kernel.org
Signed-off-by: Greg Kroah-Hartman

tty: serial: qcom-geni-serial: Add a poll_init() function

2023-03-29T08:51:52+00:00

On sc7180 Chromebooks, I did the following:
* Didn't enable earlycon in the kernel command line.
* Didn't enable serial console in the kernel command line.
* Didn't enable an agetty or any other client of "/dev/ttyMSM0".
* Added "kgdboc=ttyMSM0" to the kernel command line.

After I did that, I tried to enter kdb with this command over an ssh
session:
  echo g > /proc/sysrq-trigger

When I did that the system just hung.

Although I thought I'd tested this scenario before, I couldn't go back
and find a time when it was working. Previous testing must have relied
on either the UART acting as the kernel console or an agetty running.

It turns out to be pretty easy to fix: we can just use
qcom_geni_serial_port_setup() as the .poll_init() function. This,
together with the patch ("serial: uart_poll_init() should power on the
UART"), allows the debugger to work even if there are no other users
of the serial port.

Signed-off-by: Douglas Anderson 
Link: https://lore.kernel.org/r/20230316132027.RESEND.2.Ie678853bb101091afe78cc8c22344bf3ff3aed74@changeid
Signed-off-by: Greg Kroah-Hartman

serial: qcom-geni: drop bogus uart_write_wakeup()

2023-03-09T16:27:53+00:00

Drop the bogus uart_write_wakeup() from when setting up a new DMA
transfer, which does not free up any more space in the ring buffer.

Any pending writers will be woken up when the transfer completes.

Cc: stable 
Signed-off-by: Johan Hovold 
Reviewed-by: Douglas Anderson 
Reviewed-by: Srinivas Kandagatla 
Tested-by: Srinivas Kandagatla 
Reviewed-by: Andrew Halaney 
Tested-by: Andrew Halaney  # sa8540p-ride
Link: https://lore.kernel.org/r/20230307164405.14218-5-johan+linaro@kernel.org
Signed-off-by: Greg Kroah-Hartman

serial: qcom-geni: fix mapping of empty DMA buffer

2023-03-09T16:27:50+00:00

Make sure that there is data in the ring buffer before trying to set up
a zero-length DMA transfer.

This specifically fixes the following warning when unmapping the empty
buffer on the sc8280xp-crd:

   WARNING: CPU: 0 PID: 138 at drivers/iommu/dma-iommu.c:1046 iommu_dma_unmap_page+0xbc/0xd8
   ...
   Call trace:
    iommu_dma_unmap_page+0xbc/0xd8
    dma_unmap_page_attrs+0x30/0x1c8
    geni_se_tx_dma_unprep+0x28/0x38
    qcom_geni_serial_isr+0x358/0x75c

Fixes: 2aaa43c70778 ("tty: serial: qcom-geni-serial: add support for serial engine DMA")
Cc: stable 
Cc: Bartosz Golaszewski 
Signed-off-by: Johan Hovold 
Reviewed-by: Douglas Anderson 
Reviewed-by: Srinivas Kandagatla 
Tested-by: Srinivas Kandagatla 
Reviewed-by: Andrew Halaney 
Tested-by: Andrew Halaney  # sa8540p-ride
Link: https://lore.kernel.org/r/20230307164405.14218-4-johan+linaro@kernel.org
Signed-off-by: Greg Kroah-Hartman

serial: qcom-geni: fix DMA mapping leak on shutdown

2023-03-09T16:27:47+00:00

Fix what appears to be a copy-paste error that can lead to a leaked DMA
mapping on close() and failure to restart TX after the port is reopened.

Note that rx_dma_addr is generally NULL when
qcom_geni_serial_stop_tx_dma() is called as part of shutdown() (but
tx_dma_addr need not be).

Fixes: 2aaa43c70778 ("tty: serial: qcom-geni-serial: add support for serial engine DMA")
Cc: stable 
Cc: Bartosz Golaszewski 
Signed-off-by: Johan Hovold 
Reviewed-by: Douglas Anderson 
Reviewed-by: Srinivas Kandagatla 
Tested-by: Srinivas Kandagatla 
Reviewed-by: Andrew Halaney 
Tested-by: Andrew Halaney  # sa8540p-ride
Link: https://lore.kernel.org/r/20230307164405.14218-3-johan+linaro@kernel.org
Signed-off-by: Greg Kroah-Hartman

serial: qcom-geni: fix console shutdown hang

2023-03-09T16:27:44+00:00

A recent commit added back the calls top stop tx and rx to shutdown()
which had previously been removed by commit e83766334f96 ("tty: serial:
qcom_geni_serial: No need to stop tx/rx on UART shutdown") in order to
be able to use kgdb after stopping the getty.

Not only did this again break kgdb, but it also broke serial consoles
more generally by hanging TX when stopping the getty during reboot.

The underlying problem has been there since the driver was first merged
and fixing it is going to be a bit involved so simply stop calling the
broken stop functions during shutdown for consoles for now.

Fixes: d8aca2f96813 ("tty: serial: qcom-geni-serial: stop operations in progress at shutdown")
Cc: stable 
Cc: Bartosz Golaszewski 
Signed-off-by: Johan Hovold 
Reviewed-by: Douglas Anderson 
Reviewed-by: Srinivas Kandagatla 
Tested-by: Srinivas Kandagatla 
Reviewed-by: Andrew Halaney 
Tested-by: Andrew Halaney  # sa8540p-ride
Link: https://lore.kernel.org/r/20230307164405.14218-2-johan+linaro@kernel.org
Signed-off-by: Greg Kroah-Hartman

soc: qcom: geni-se: Move qcom-geni-se.h to linux/soc/qcom/geni-se.h

2023-02-09T12:27:07+00:00

Move include/linux/qcom-geni-se.h to include/linux/soc/qcom/geni-se.h.
This removes 1 of a few remaining Qualcomm-specific headers into a more
approciate subdirectory under include/.

Signed-off-by: Elliot Berman 
Acked-by: Bjorn Andersson 
Acked-by: Wolfram Sang  # for I2C
Reviewed-by: Guru Das Srinagesh 
Link: https://lore.kernel.org/r/20230203210133.3552796-1-quic_eberman@quicinc.com
Signed-off-by: Greg Kroah-Hartman

serial: qcom_geni: Fix variable naming

2023-01-23T17:51:50+00:00

Commit 2aaa43c70778 ("tty: serial: qcom-geni-serial: add support for
serial engine DMA") renamed rx_fifo member to rf_buf which caused a
build failure when b8caf69a6946 ("tty: serial: qcom-geni-serial: fix
slab-out-of-bounds on RX FIFO buffer") from tty-linus was merged into
tty-next.

Fix the member variable name.

Fixes: 7a6aa989f2e8 ("Merge 6.2-rc5 into tty-next")
Reported-by: Stephen Rothwell 
Signed-off-by: Ilpo Järvinen 
Link: https://lore.kernel.org/r/20230123173857.40695-2-ilpo.jarvinen@linux.intel.com
Signed-off-by: Greg Kroah-Hartman

Merge 6.2-rc5 into tty-next

2023-01-22T11:55:13+00:00

We need the serial/tty changes into this branch as well.

Signed-off-by: Greg Kroah-Hartman