The UCR4_OREN should be disabled before disabling the uart receiver in
.stop_rx() instead of in the .shutdown().
Otherwise, if we have the overrun error during the receiver disable
process, the overrun interrupt will keep trigging until we disable the
OREN interrupt in the .shutdown(), because the ORE status can only be
cleared when read the rx FIFO or reset the controller. Although the
called time between the receiver disable and OREN disable in .shutdown()
is very short, there is still the risk of endless interrupt during this
short period of time. So here change to disable OREN before the receiver
been disabled in .stop_rx().
Signed-off-by: Fugang Duan <fugang.duan@nxp.com>
Signed-off-by: Sherry Sun <sherry.sun@nxp.com>
Link: https://lore.kernel.org/r/20211125020349.4980-1-sherry.sun@nxp.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
During console setup imx_uart_console_setup() enables clocks, but they
are never disabled when the console is unregistered, this leads to
clk_prepare_enable() being called multiple times without a matching
clk_disable_unprepare() in case of console unregister.
Ensure that clock enable/disable are balanced adding
clk_disable_unprepare() in the console exit callback.
Signed-off-by: Francesco Dolcini <francesco.dolcini@toradex.com>
Link: https://lore.kernel.org/r/20211020192643.476895-3-francesco.dolcini@toradex.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Force-threaded interrupt handlers used to run with interrupts enabled,
something which could lead to deadlocks in case a threaded handler
shared a lock with code running in hard interrupt context (e.g. timer
callbacks) and did not explicitly disable interrupts.
This was specifically the case for serial drivers that take the port
lock in their console write path as printk can be called from hard
interrupt context also with forced threading ("threadirqs").
Since commit 81e2073c17 ("genirq: Disable interrupts for force
threaded handlers") interrupt handlers always run with interrupts
disabled on non-RT so that drivers no longer need to do handle this.
Drop the now obsolete workaround added by commit 33f16855dc ("tty:
serial: imx: fix potential deadlock").
Cc: Sam Nobs <samuel.nobs@taitradio.com>
Cc: Uwe Kleine-König <u.kleine-koenig@pengutronix.de>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Cc: Peter Zijlstra <peterz@infradead.org>
Signed-off-by: Johan Hovold <johan@kernel.org>
Link: https://lore.kernel.org/r/20210322111036.31966-1-johan@kernel.org
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Since 5.10-rc1 i.MX is a devicetree-only platform and the NULL check on
of_device_get_match_data() is no longer needed.
This check was only needed when this driver supported both DT and non-DT
platforms.
Remove the unneeded of_device_get_match_data() NULL check.
Signed-off-by: Fabio Estevam <festevam@gmail.com>
Link: https://lore.kernel.org/r/20201126124643.3371-1-festevam@gmail.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
As described in Documentation, poll_init() is called by kgdb to initialize
hardware which supports both poll_put_char() and poll_get_char().
It's necessary to enable TXEN bit, otherwise, it will cause hardware fault
and kernel panic when calling imx_poll_put_char().
Generally, if use /dev/ttymxc0 as kgdb console as well as system
console, ttymxc0 is initialized early by system console which does enable
TXEN bit.But when use /dev/ttymxc1 as kgbd console, ttymxc1 is only
initialized by imx_poll_init() cannot enable the TXEN bit, which will
cause kernel panic.
Signed-off-by: Mingrui Ren <jiladahe1997@gmail.com>
Link: https://lore.kernel.org/r/20201202072543.151-1-972931182@qq.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Enabling the lock dependency validator has revealed
that the way spinlocks are used in the IMX serial
port could result in a deadlock.
Specifically, imx_uart_int() acquires a spinlock
without disabling the interrupts, meaning that another
interrupt could come along and try to acquire the same
spinlock, potentially causing the two to wait for each
other indefinitely.
Use spin_lock_irqsave() instead to disable interrupts
upon acquisition of the spinlock.
Fixes: c974991d26 ("tty:serial:imx: use spin_lock instead of spin_lock_irqsave in isr")
Reviewed-by: Uwe Kleine-König <u.kleine-koenig@pengutronix.de>
Signed-off-by: Sam Nobs <samuel.nobs@taitradio.com>
Link: https://lore.kernel.org/r/1604955006-9363-1-git-send-email-samuel.nobs@taitradio.com
Cc: stable <stable@vger.kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
The IPG clock is disabled at the end of imx_uart_shutdown(); we really
don't want to run any IRQ handlers after this point.
At least on i.MX8MN, the UART will happily continue to generate interrupts
even with its clocks disabled, but in this state, all register writes are
ignored (which will cause the shadow registers to differ from the actual
register values, resulting in all kinds of weirdness).
In a transfer without DMA, this could lead to the following sequence of
events:
- The UART finishes its transmission while imx_uart_shutdown() is run,
triggering the TXDC interrupt (we can trigger this fairly reliably by
writing a single byte to the TTY and closing it right away)
- imx_uart_shutdown() finishes, disabling the UART clocks
- imx_uart_int() -> imx_uart_transmit_buffer() -> imx_uart_stop_tx()
imx_uart_stop_tx() should now clear UCR4_TCEN to disable the TXDC
interrupt, but this register write is ineffective. This results in an
interrupt storm.
To disable all interrupts in the same place, and to avoid setting UCR4
twice, clearing UCR4_OREN is moved below del_timer_sync() as well; this
should be harmless.
Signed-off-by: Matthias Schiffer <matthias.schiffer@ew.tq-group.com>
Link: https://lore.kernel.org/r/20200925082412.12960-1-matthias.schiffer@ew.tq-group.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
This patch imitates 6e0a5de213 ("serial: 8250: Use hrtimers for
rs485 delays") in replacing the previously used classic timers
with hrtimers. The old way provided a too coarse resolution on
systems with configs of less than 1000 HZ.
Use of hrtimers addresses this and can be easily extended to
support microsecond resolution in future when support
for this arrives upstream.
Signed-off-by: Ahmad Fatoum <a.fatoum@pengutronix.de>
Link: https://lore.kernel.org/r/20200714093012.21621-3-uwe@kleine-koenig.org
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
The AGTIM flag must be cleared explicitly, otherwise the IRQ handler
will be called in an endless loop.
Fortunately, this issue currently doesn't affect mainline kernels in
practice, as the the RX FIFO trigger level is set to 1 in UFCR. When
setting the trigger level to a higher number, the issue is trivially
reproducible by any RX without DMA that doesn't fill the FIFO up to the
configured level.
Signed-off-by: Matthias Schiffer <matthias.schiffer@ew.tq-group.com>
Link: https://lore.kernel.org/r/20200528154747.14201-1-matthias.schiffer@ew.tq-group.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
The commit a3cb39d258
("serial: core: Allow detach and attach serial device for console")
changed a bit logic behind lock initialization since for most of the console
driver it's supposed to have lock already initialized even if console is not
enabled. However, it's not the case for Freescale IMX console.
Initialize lock explicitly in the ->probe().
Note, there is still an open question should or shouldn't not this driver
register console properly.
Fixes: a3cb39d258 ("serial: core: Allow detach and attach serial device for console")
Reported-by: Guenter Roeck <linux@roeck-us.net>
Cc: stable <stable@vger.kernel.org>
Signed-off-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Link: https://lore.kernel.org/r/20200525105952.13744-1-andriy.shevchenko@linux.intel.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
We're about to amend uart_get_rs485_mode() to support a GPIO pin for
rs485 bus termination. Retrieving the GPIO descriptor may fail, so
allow uart_get_rs485_mode() to return an errno and change all callers
to check for failure.
The GPIO descriptor is going to be stored in struct uart_port. Pass
that struct to uart_get_rs485_mode() in lieu of a struct device and
struct serial_rs485, both of which are directly accessible from struct
uart_port.
A few drivers call uart_get_rs485_mode() before setting the struct
device pointer in struct uart_port. Shuffle those calls around where
necessary.
[Heiko Stuebner did the ar933x_uart.c portion, hence his Signed-off-by.]
Signed-off-by: Heiko Stuebner <heiko@sntech.de>
Signed-off-by: Lukas Wunner <lukas@wunner.de>
Link: https://lore.kernel.org/r/271e814af4b0db3bffbbb74abf2b46b75add4516.1589285873.git.lukas@wunner.de
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
The peripheral has support for inverting its input and/or output
signals. This is useful if the hardware flips polarity of the
peripheral's signal, such as swapped +/- pins on an RS-422 transceiver,
or an inverting level shifter. Add support for these control registers
via the device tree binding.
As part of this change, make the writes of the various registers more
uniform by moving the UCR3 block up near the other registers' blocks,
since the INVT bit must be set before enabling the peripheral.
Signed-off-by: George Hilliard <ghilliard@kopismobile.com>
Acked-by: Uwe Kleine-König <u.kleine-koenig@pengutronix.de>
Link: https://lore.kernel.org/r/20200226222319.18383-3-ghilliard@kopismobile.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
The main irq handler function starts by first masking disabled
interrupts in the status register values to ensure to only handle
enabled interrupts. This is important as when the RX path in the
hardware is disabled reading the RX fifo results in an external abort.
This checking must be done under the port lock, otherwise the following
can happen:
CPU1 | CPU2
|
irq triggers as there are chars |
in the RX fifo |
| grab port lock
imx_uart_int finds RRDY enabled |
and calls imx_uart_rxint which |
has to wait for port lock |
| disable RX (e.g. because we're
| using RS485 with !RX_DURING_TX)
|
| release port lock
read from RX fifo with RX |
disabled => exception |
So take the port lock only once in imx_uart_int() instead of in the
functions called from there.
Reported-by: Andre Renaud <arenaud@designa-electronics.com>
Cc: stable@vger.kernel.org
Signed-off-by: Uwe Kleine-König <u.kleine-koenig@pengutronix.de>
Link: https://lore.kernel.org/r/20200121071702.20150-1-u.kleine-koenig@pengutronix.de
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
All i.MX SoCs except i.MX1 have ONLY one necessary IRQ, use
platform_get_irq_optional() to get second/third IRQ which are
optional to avoid below error message during probe:
[ 0.726219] imx-uart 30860000.serial: IRQ index 1 not found
[ 0.731329] imx-uart 30860000.serial: IRQ index 2 not found
Fixes: 7723f4c5ec ("driver core: platform: Add an error message to platform_get_irq*()")
Signed-off-by: Anson Huang <Anson.Huang@nxp.com>
Link: https://lore.kernel.org/r/1570614559-11900-1-git-send-email-Anson.Huang@nxp.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Using only 4 DMA periods for UART RX is very few if we have a high
frequency of small transfers - like in our case using Bluetooth with
many small packets via UART - causing many dma transfers but in each
only filling a fraction of a single buffer. Such a case may lead to
the situation that DMA RX transfer is triggered but no free buffer is
available. When this happens dma channel ist stopped - with the patch
"dmaengine: imx-sdma: fix dma freezes" temporarily only - with the
possible consequences that:
with disabled hw flow control:
If enough data is incoming on UART port the RX FIFO runs over and
characters will be lost. What then happens depends on upper layer.
with enabled hw flow control:
If enough data is incoming on UART port the RX FIFO reaches a level
where CTS is deasserted and remote device sending the data stops.
If it fails to stop timely the i.MX' RX FIFO may run over and data
get lost. Otherwise it's internal TX buffer may getting filled to
a point where it runs over and data is again lost. It depends on
the remote device how this case is handled and if it is recoverable.
Obviously we want to avoid having no free buffers available. So we
decrease the size of the buffers and increase their number and the
total buffer size.
Signed-off-by: Philipp Puschmann <philipp.puschmann@emlix.com>
Reviewed-by: Lucas Stach <l.stach@pengutronix.de>
Link: https://lore.kernel.org/r/20190923135916.1212-1-philipp.puschmann@emlix.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
imx_set_termios(): avoid writing baud rate divider registers when the
values to be written are the same as current. Any writing seems to
restart transmission/receiving logic in the hardware, that leads to
data breakage even when rate doesn't in fact change. E.g., user
switches RTS/CTS handshake and suddenly gets broken bytes.
Signed-off-by: Sergey Organov <sorganov@gmail.com>
Link: https://lore.kernel.org/r/1567017475-11919-5-git-send-email-sorganov@gmail.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
imx_set_termios(): stopping receiver and transmitter does harm when
something that doesn't touch transmission format/rate changes, such as
RTS/CTS handshake.
OTOH, it does no good on baud rate or format change, as
synchronization on upper-level protocols is still required to do it
right.
Therefore, just stop doing it.
Signed-off-by: Sergey Organov <sorganov@gmail.com>
Link: https://lore.kernel.org/r/1567017475-11919-3-git-send-email-sorganov@gmail.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
imx_uart_set_termios() called imx_uart_rts_active(), or
imx_uart_rts_inactive() before taking port->port.lock.
As a consequence, sport->port.mctrl that these functions modify
could have been changed without holding port->port.lock.
Moved locking of port->port.lock above the calls to fix the issue.
Signed-off-by: Sergey Organov <sorganov@gmail.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
dev_info() is more appropriate for printing messages inside drivers, so
switch to dev_info().
Signed-off-by: Fabio Estevam <festevam@gmail.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Each time the DMA engine signals a transaction error the driver prints
a message at error level. Getting transaction errors is pretty much
expected on baudrate mismatches and the correspoding error counters
are increased in this case properly. Remove the error message which
is possibly repeated at a very high rate which can lock up the whole
system.
Signed-off-by: Sascha Hauer <s.hauer@pengutronix.de>
Reviewed-by: Fabio Estevam <festevam@gmail.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
The ipg clock only needs to be unprepared in case preparing
per clock fails. The ipg clock has already disabled at the point.
Fixes: 1cf93e0d54 ("serial: imx: remove the uart_console() check")
Signed-off-by: Stefan Agner <stefan@agner.ch>
Reviewed-by: Uwe Kleine-König <u.kleine-koenig@pengutronix.de>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
