linux.git/drivers/tty/serial/msm_serial.c, branch v5.7 Linux kernel source tree tty: serial: msm_serial: RX SW/FIFO mode fallback 2020-01-14T13:07:51+00:00 Loic Poulain loic.poulain@linaro.org 2020-01-10T08:58:04+00:00 76460fbd845b2b55d6fdb651b9dac4ef8122038b During db410c stress test and when the system is low on memory, the UART/console becomes unresponsive and never recover back. This has been narrowed down to the msm_start_rx_dma which does not manage error cases correctly (e.g. dma mapping failure), indeed, when an error happens, dma transfer is simply discarded and so never completed, leading to unconfigured RX path. This patch fixes this issue by switching to SW/FIFO mode in case of DMA issue. This mainly consists in resetting the receiver to apply RX BAM/DMA disabling change and re-enabling the RX level and stale interrupts (previously disabled for DMA transfers). The DMA will be re-enabled once memory is available since the SW/FIFO read function (msm_handle_rx_dm) retries to start dma on completion. Signed-off-by: Loic Poulain <loic.poulain@linaro.org> Link: https://lore.kernel.org/r/1578646684-17379-1-git-send-email-loic.poulain@linaro.org Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> 
During db410c stress test and when the system is low on memory,
the UART/console becomes unresponsive and never recover back.
This has been narrowed down to the msm_start_rx_dma which does
not manage error cases correctly (e.g. dma mapping failure),
indeed, when an error happens, dma transfer is simply discarded
and so never completed, leading to unconfigured RX path.

This patch fixes this issue by switching to SW/FIFO mode in case
of DMA issue. This mainly consists in resetting the receiver to
apply RX BAM/DMA disabling change and re-enabling the RX level
and stale interrupts (previously disabled for DMA transfers).

The DMA will be re-enabled once memory is available since the
SW/FIFO read function (msm_handle_rx_dm) retries to start dma
on completion.

Signed-off-by: Loic Poulain <loic.poulain@linaro.org>
Link: https://lore.kernel.org/r/1578646684-17379-1-git-send-email-loic.poulain@linaro.org
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Merge 5.5-rc3 into tty-next 2019-12-23T11:59:19+00:00 Greg Kroah-Hartman gregkh@linuxfoundation.org 2019-12-23T11:59:19+00:00 749e4121d6ee7fd4495779730fbc6ae800d0317c We need the tty/serial fixes in here as well. Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> 
We need the tty/serial fixes in here as well.

Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
tty/serial: Migrate msm_serial to use has_sysrq 2019-12-18T14:04:52+00:00 Dmitry Safonov dima@arista.com 2019-12-13T00:06:24+00:00 804ca1df0914d409eca2c31b40edcb30f69cce1a The SUPPORT_SYSRQ ifdeffery is not nice as: - May create misunderstanding about sizeof(struct uart_port) between different objects - Prevents moving functions from serial_core.h - Reduces readability (well, it's ifdeffery - it's hard to follow) In order to remove SUPPORT_SYSRQ, has_sysrq variable has been added. Initialise it in driver's probe and remove ifdeffery. Cc: Andy Gross <agross@kernel.org> Cc: Bjorn Andersson <bjorn.andersson@linaro.org> Cc: linux-arm-msm@vger.kernel.org Signed-off-by: Dmitry Safonov <dima@arista.com> Link: https://lore.kernel.org/r/20191213000657.931618-26-dima@arista.com Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> 
The SUPPORT_SYSRQ ifdeffery is not nice as:
- May create misunderstanding about sizeof(struct uart_port) between
  different objects
- Prevents moving functions from serial_core.h
- Reduces readability (well, it's ifdeffery - it's hard to follow)

In order to remove SUPPORT_SYSRQ, has_sysrq variable has been added.
Initialise it in driver's probe and remove ifdeffery.

Cc: Andy Gross <agross@kernel.org>
Cc: Bjorn Andersson <bjorn.andersson@linaro.org>
Cc: linux-arm-msm@vger.kernel.org
Signed-off-by: Dmitry Safonov <dima@arista.com>
Link: https://lore.kernel.org/r/20191213000657.931618-26-dima@arista.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
tty: serial: msm_serial: Fix lockup for sysrq and oops 2019-12-12T13:26:59+00:00 Leo Yan leo.yan@linaro.org 2019-11-27T14:15:43+00:00 0e4f7f920a5c6bfe5e851e989f27b35a0cc7fb7e As the commit 677fe555cbfb ("serial: imx: Fix recursive locking bug") has mentioned the uart driver might cause recursive locking between normal printing and the kernel debugging facilities (e.g. sysrq and oops). In the commit it gave out suggestion for fixing recursive locking issue: "The solution is to avoid locking in the sysrq case and trylock in the oops_in_progress case." This patch follows the suggestion (also used the exactly same code with other serial drivers, e.g. amba-pl011.c) to fix the recursive locking issue, this can avoid stuck caused by deadlock and print out log for sysrq and oops. Fixes: 04896a77a97b ("msm_serial: serial driver for MSM7K onboard serial peripheral.") Signed-off-by: Leo Yan <leo.yan@linaro.org> Reviewed-by: Jeffrey Hugo <jeffrey.l.hugo@gmail.com> Link: https://lore.kernel.org/r/20191127141544.4277-2-leo.yan@linaro.org Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> 
As the commit 677fe555cbfb ("serial: imx: Fix recursive locking bug")
has mentioned the uart driver might cause recursive locking between
normal printing and the kernel debugging facilities (e.g. sysrq and
oops).  In the commit it gave out suggestion for fixing recursive
locking issue: "The solution is to avoid locking in the sysrq case
and trylock in the oops_in_progress case."

This patch follows the suggestion (also used the exactly same code with
other serial drivers, e.g. amba-pl011.c) to fix the recursive locking
issue, this can avoid stuck caused by deadlock and print out log for
sysrq and oops.

Fixes: 04896a77a97b ("msm_serial: serial driver for MSM7K onboard serial peripheral.")
Signed-off-by: Leo Yan <leo.yan@linaro.org>
Reviewed-by: Jeffrey Hugo <jeffrey.l.hugo@gmail.com>
Link: https://lore.kernel.org/r/20191127141544.4277-2-leo.yan@linaro.org
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
tty: serial: msm_serial: Use dma_request_chan() directly for channel request 2019-11-13T13:54:16+00:00 Peter Ujfalusi peter.ujfalusi@ti.com 2019-11-13T09:46:17+00:00 19b6ecfca6b89cd3fb80af6c9b32afa54b442481 dma_request_slave_channel_reason() is: #define dma_request_slave_channel_reason(dev, name) \ dma_request_chan(dev, name) Signed-off-by: Peter Ujfalusi <peter.ujfalusi@ti.com> Link: https://lore.kernel.org/r/20191113094618.1725-3-peter.ujfalusi@ti.com Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> 
dma_request_slave_channel_reason() is:
#define dma_request_slave_channel_reason(dev, name) \
	dma_request_chan(dev, name)

Signed-off-by: Peter Ujfalusi <peter.ujfalusi@ti.com>
Link: https://lore.kernel.org/r/20191113094618.1725-3-peter.ujfalusi@ti.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
tty: serial: msm_serial: Fix flow control 2019-11-04T16:42:28+00:00 Jeffrey Hugo jeffrey.l.hugo@gmail.com 2019-10-21T15:46:16+00:00 b027ce258369cbfa88401a691c23dad01deb9f9b hci_qca interfaces to the wcn3990 via a uart_dm on the msm8998 mtp and Lenovo Miix 630 laptop. As part of initializing the wcn3990, hci_qca disables flow, configures the uart baudrate, and then reenables flow - at which point an event is expected to be received over the uart from the wcn3990. It is observed that this event comes after the baudrate change but before hci_qca re-enables flow. This is unexpected, and is a result of msm_reset() being broken. According to the uart_dm hardware documentation, it is recommended that automatic hardware flow control be enabled by setting RX_RDY_CTL. Auto hw flow control will manage RFR based on the configured watermark. When there is space to receive data, the hw will assert RFR. When the watermark is hit, the hw will de-assert RFR. The hardware documentation indicates that RFR can me manually managed via CR when RX_RDY_CTL is not set. SET_RFR asserts RFR, and RESET_RFR de-asserts RFR. msm_reset() is broken because after resetting the hardware, it unconditionally asserts RFR via SET_RFR. This enables flow regardless of the current configuration, and would undo a previous flow disable operation. It should instead de-assert RFR via RESET_RFR to block flow until the hardware is reconfigured. msm_serial should rely on the client to specify that flow should be enabled, either via mctrl() or the termios structure, and only assert RFR in response to those triggers. Fixes: 04896a77a97b ("msm_serial: serial driver for MSM7K onboard serial peripheral.") Signed-off-by: Jeffrey Hugo <jeffrey.l.hugo@gmail.com> Reviewed-by: Bjorn Andersson <bjorn.andersson@linaro.org> Cc: stable <stable@vger.kernel.org> Reviewed-by: Andy Gross <agross@kernel.org> Link: https://lore.kernel.org/r/20191021154616.25457-1-jeffrey.l.hugo@gmail.com Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> 
hci_qca interfaces to the wcn3990 via a uart_dm on the msm8998 mtp and
Lenovo Miix 630 laptop.  As part of initializing the wcn3990, hci_qca
disables flow, configures the uart baudrate, and then reenables flow - at
which point an event is expected to be received over the uart from the
wcn3990.  It is observed that this event comes after the baudrate change
but before hci_qca re-enables flow. This is unexpected, and is a result of
msm_reset() being broken.

According to the uart_dm hardware documentation, it is recommended that
automatic hardware flow control be enabled by setting RX_RDY_CTL.  Auto
hw flow control will manage RFR based on the configured watermark.  When
there is space to receive data, the hw will assert RFR.  When the watermark
is hit, the hw will de-assert RFR.

The hardware documentation indicates that RFR can me manually managed via
CR when RX_RDY_CTL is not set.  SET_RFR asserts RFR, and RESET_RFR
de-asserts RFR.

msm_reset() is broken because after resetting the hardware, it
unconditionally asserts RFR via SET_RFR.  This enables flow regardless of
the current configuration, and would undo a previous flow disable
operation.  It should instead de-assert RFR via RESET_RFR to block flow
until the hardware is reconfigured.  msm_serial should rely on the client
to specify that flow should be enabled, either via mctrl() or the termios
structure, and only assert RFR in response to those triggers.

Fixes: 04896a77a97b ("msm_serial: serial driver for MSM7K onboard serial peripheral.")
Signed-off-by: Jeffrey Hugo <jeffrey.l.hugo@gmail.com>
Reviewed-by: Bjorn Andersson <bjorn.andersson@linaro.org>
Cc: stable <stable@vger.kernel.org>
Reviewed-by: Andy Gross <agross@kernel.org>
Link: https://lore.kernel.org/r/20191021154616.25457-1-jeffrey.l.hugo@gmail.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
tty: serial: msm_serial: avoid system lockup condition 2019-06-10T17:42:35+00:00 Jorge Ramirez-Ortiz jorge.ramirez-ortiz@linaro.org 2019-06-10T17:23:08+00:00 ba3684f99f1b25d2a30b6956d02d339d7acb9799 The function msm_wait_for_xmitr can be taken with interrupts disabled. In order to avoid a potential system lockup - demonstrated under stress testing conditions on SoC QCS404/5 - make sure we wait for a bounded amount of time. Tested on SoC QCS404. Signed-off-by: Jorge Ramirez-Ortiz <jorge.ramirez-ortiz@linaro.org> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> 
The function msm_wait_for_xmitr can be taken with interrupts
disabled. In order to avoid a potential system lockup - demonstrated
under stress testing conditions on SoC QCS404/5 - make sure we wait
for a bounded amount of time.

Tested on SoC QCS404.

Signed-off-by: Jorge Ramirez-Ortiz <jorge.ramirez-ortiz@linaro.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
tty: serial: msm_serial: Fix XON/XOFF 2019-05-21T10:18:16+00:00 Jorge Ramirez-Ortiz jorge.ramirez-ortiz@linaro.org 2019-05-20T18:38:48+00:00 61c0e37950b88bad590056286c1d766b1f167f4e When the tty layer requests the uart to throttle, the current code executing in msm_serial will trigger "Bad mode in Error Handler" and generate an invalid stack frame in pstore before rebooting (that is if pstore is indeed configured: otherwise the user shall just notice a reboot with no further information dumped to the console). This patch replaces the PIO byte accessor with the word accessor already used in PIO mode. Fixes: 68252424a7c7 ("tty: serial: msm: Support big-endian CPUs") Cc: stable@vger.kernel.org Signed-off-by: Jorge Ramirez-Ortiz <jorge.ramirez-ortiz@linaro.org> Reviewed-by: Bjorn Andersson <bjorn.andersson@linaro.org> Reviewed-by: Stephen Boyd <swboyd@chromium.org> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> 
When the tty layer requests the uart to throttle, the current code
executing in msm_serial will trigger "Bad mode in Error Handler" and
generate an invalid stack frame in pstore before rebooting (that is if
pstore is indeed configured: otherwise the user shall just notice a
reboot with no further information dumped to the console).

This patch replaces the PIO byte accessor with the word accessor
already used in PIO mode.

Fixes: 68252424a7c7 ("tty: serial: msm: Support big-endian CPUs")
Cc: stable@vger.kernel.org
Signed-off-by: Jorge Ramirez-Ortiz <jorge.ramirez-ortiz@linaro.org>
Reviewed-by: Bjorn Andersson <bjorn.andersson@linaro.org>
Reviewed-by: Stephen Boyd <swboyd@chromium.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
tty: serial: msm_serial: Remove __init from msm_console_setup() 2019-02-19T12:42:08+00:00 Jeffrey Hugo jhugo@codeaurora.org 2019-02-17T05:05:52+00:00 be24c270185930997b55e20a859a954b2f4eaa46 Due to the complexities of modern Qualcomm SoCs, about a half dozen drivers must successfully probe before the clocks for the console are present, and the console can successfully probe. Depending on several random factors such as probe order and modules vs builtin, msm_serial may not be able to successfully probe for some, at which point, __init annotated functions may become unmapped. If this occurs, msm_console_setup() will be called from the probe path, but will no longer exist, resulting in a kernel panic. Resolve this issue by removing the __init annotation from msm_console_setup(). Signed-off-by: Jeffrey Hugo <jhugo@codeaurora.org> Reviewed-by: Bjorn Andersson <bjorn.andersson@linaro.org> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> 
Due to the complexities of modern Qualcomm SoCs, about a half dozen drivers
must successfully probe before the clocks for the console are present, and
the console can successfully probe.  Depending on several random factors
such as probe order and modules vs builtin, msm_serial may not be able to
successfully probe for some, at which point, __init annotated functions
may become unmapped.  If this occurs, msm_console_setup() will be called
from the probe path, but will no longer exist, resulting in a kernel
panic.

Resolve this issue by removing the __init annotation from
msm_console_setup().

Signed-off-by: Jeffrey Hugo <jhugo@codeaurora.org>
Reviewed-by: Bjorn Andersson <bjorn.andersson@linaro.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
tty: serial: msm_serial: Add __maybe_unused to suspend/resume callbacks 2018-05-14T11:41:05+00:00 Pascal Huerst pascal.huerst@gmail.com 2018-04-25T15:22:07+00:00 2ccdb55e52a126aa51a64a2244d8b60c16f370cc As stated under "20) Conditional Compilation" in coding-style.rst. We shall rather use __maybe_unused than preprocessor macros in such cases. Signed-off-by: Pascal Huerst <pascal.huerst@gmail.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> 
As stated under "20) Conditional Compilation" in coding-style.rst. We
shall rather use __maybe_unused than preprocessor macros in such cases.

Signed-off-by: Pascal Huerst <pascal.huerst@gmail.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>