linux-toradex.git/drivers/tty, branch v3.10.62 Linux kernel for Apalis and Colibri modules tty: Fix high cpu load if tty is unreleaseable 2014-11-14T16:48:00+00:00 Peter Hurley peter@hurleysoftware.com 2014-10-16T17:51:30+00:00 a88f5eaa6802026c97ebe34c2b961d60ad9c5bfa commit 37b164578826406a173ca7c20d9ba7430134d23e upstream. Kernel oops can cause the tty to be unreleaseable (for example, if n_tty_read() crashes while on the read_wait queue). This will cause tty_release() to endlessly loop without sleeping. Use a killable sleep timeout which grows by 2n+1 jiffies over the interval [0, 120 secs.) and then jumps to forever (but still killable). NB: killable just allows for the task to be rewoken manually, not to be terminated. Signed-off-by: Peter Hurley <peter@hurleysoftware.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> 
commit 37b164578826406a173ca7c20d9ba7430134d23e upstream.

Kernel oops can cause the tty to be unreleaseable (for example, if
n_tty_read() crashes while on the read_wait queue). This will cause
tty_release() to endlessly loop without sleeping.

Use a killable sleep timeout which grows by 2n+1 jiffies over the interval
[0, 120 secs.) and then jumps to forever (but still killable).

NB: killable just allows for the task to be rewoken manually, not
to be terminated.

Signed-off-by: Peter Hurley <peter@hurleysoftware.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
serial: Fix divide-by-zero fault in uart_get_divisor() 2014-11-14T16:47:58+00:00 Peter Hurley peter@hurleysoftware.com 2014-10-16T17:46:38+00:00 a8fb82d5f59da4d42a722043566376a82a3b4644 commit 547039ec502076e60034eeb79611df3433a99b7d upstream. uart_get_baud_rate() will return baud == 0 if the max rate is set to the "magic" 38400 rate and the SPD_* flags are also specified. On the first iteration, if the current baud rate is higher than the max, the baud rate is clamped at the max (which in the degenerate case is 38400). On the second iteration, the now-"magic" 38400 baud rate selects the possibly higher alternate baud rate indicated by the SPD_* flag. Since only two loop iterations are performed, the loop is exited, a kernel WARNING is generated and a baud rate of 0 is returned. Reproducible with: setserial /dev/ttyS0 spd_hi base_baud 38400 Only perform the "magic" 38400 -> SPD_* baud transform on the first loop iteration, which prevents the degenerate case from recognizing the clamped baud rate as the "magic" 38400 value. Reported-by: Robert Święcki <robert@swiecki.net> Signed-off-by: Peter Hurley <peter@hurleysoftware.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> 
commit 547039ec502076e60034eeb79611df3433a99b7d upstream.

uart_get_baud_rate() will return baud == 0 if the max rate is set
to the "magic" 38400 rate and the SPD_* flags are also specified.
On the first iteration, if the current baud rate is higher than the
max, the baud rate is clamped at the max (which in the degenerate
case is 38400). On the second iteration, the now-"magic" 38400 baud
rate selects the possibly higher alternate baud rate indicated by
the SPD_* flag. Since only two loop iterations are performed, the
loop is exited, a kernel WARNING is generated and a baud rate of
0 is returned.

Reproducible with:
 setserial /dev/ttyS0 spd_hi base_baud 38400

Only perform the "magic" 38400 -> SPD_* baud transform on the first
loop iteration, which prevents the degenerate case from recognizing
the clamped baud rate as the "magic" 38400 value.

Reported-by: Robert Święcki <robert@swiecki.net>
Signed-off-by: Peter Hurley <peter@hurleysoftware.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
serial: 8250_dma: check the result of TX buffer mapping 2014-10-05T21:54:15+00:00 Heikki Krogerus heikki.krogerus@linux.intel.com 2014-04-28T12:59:56+00:00 1828891837182b3ae80cc83e85b4506df016557f commit d4089a332883ad969700aac5dd4dd5f1c4fee825 upstream. Using dma_mapping_error() to make sure the mapping did not fail. Signed-off-by: Heikki Krogerus <heikki.krogerus@linux.intel.com> Cc: "Petallo, MauriceX R" <mauricex.r.petallo@intel.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> 
commit d4089a332883ad969700aac5dd4dd5f1c4fee825 upstream.

Using dma_mapping_error() to make sure the mapping did not
fail.

Signed-off-by: Heikki Krogerus <heikki.krogerus@linux.intel.com>
Cc: "Petallo, MauriceX R" <mauricex.r.petallo@intel.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
serial: core: Preserve termios c_cflag for console resume 2014-09-05T23:28:35+00:00 Peter Hurley peter@hurleysoftware.com 2014-07-09T13:21:14+00:00 fca04198d5b8e48a535df52ada1b6b384474cacc commit ae84db9661cafc63d179e1d985a2c5b841ff0ac4 upstream. When a tty is opened for the serial console, the termios c_cflag settings are inherited from the console line settings. However, if the tty is subsequently closed, the termios settings are lost. This results in a garbled console if the console is later suspended and resumed. Preserve the termios c_cflag for the serial console when the tty is shutdown; this reflects the most recent line settings. Fixes: Bugzilla #69751, 'serial console does not wake from S3' Reported-by: Valerio Vanni <valerio.vanni@inwind.it> Acked-by: Alan Cox <alan@linux.intel.com> Signed-off-by: Peter Hurley <peter@hurleysoftware.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> 
commit ae84db9661cafc63d179e1d985a2c5b841ff0ac4 upstream.

When a tty is opened for the serial console, the termios c_cflag
settings are inherited from the console line settings.
However, if the tty is subsequently closed, the termios settings
are lost. This results in a garbled console if the console is later
suspended and resumed.

Preserve the termios c_cflag for the serial console when the tty
is shutdown; this reflects the most recent line settings.

Fixes: Bugzilla #69751, 'serial console does not wake from S3'
Reported-by: Valerio Vanni <valerio.vanni@inwind.it>
Acked-by: Alan Cox <alan@linux.intel.com>
Signed-off-by: Peter Hurley <peter@hurleysoftware.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
sunsab: Fix detection of BREAK on sunsab serial console 2014-08-14T01:24:16+00:00 Christopher Alexander Tobias Schulze cat.schulze@alice-dsl.net 2014-08-03T14:01:53+00:00 ff0adae5df0ff94592f03f84c952e624f0945a7c [ Upstream commit fe418231b195c205701c0cc550a03f6c9758fd9e ] Fix detection of BREAK on sunsab serial console: BREAK detection was only performed when there were also serial characters received simultaneously. To handle all BREAKs correctly, the check for BREAK and the corresponding call to uart_handle_break() must also be done if count == 0, therefore duplicate this code fragment and pull it out of the loop over the received characters. Patch applies to 3.16-rc6. Signed-off-by: Christopher Alexander Tobias Schulze <cat.schulze@alice-dsl.net> Signed-off-by: David S. Miller <davem@davemloft.net> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> 
[ Upstream commit fe418231b195c205701c0cc550a03f6c9758fd9e ]

Fix detection of BREAK on sunsab serial console: BREAK detection was only
performed when there were also serial characters received simultaneously.
To handle all BREAKs correctly, the check for BREAK and the corresponding
call to uart_handle_break() must also be done if count == 0, therefore
duplicate this code fragment and pull it out of the loop over the received
characters.

Patch applies to 3.16-rc6.

Signed-off-by: Christopher Alexander Tobias Schulze <cat.schulze@alice-dsl.net>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
serial: 8250_dw: Fix LCR workaround regression 2014-07-09T18:14:02+00:00 James Hogan james.hogan@imgtec.com 2013-12-10T22:28:04+00:00 d791a3e3ebce3b1f91381bbe2eee5224612b7d51 commit 6979f8d28049879e6147767d93ba6732c8bd94f4 upstream. Commit c49436b657d0 (serial: 8250_dw: Improve unwritable LCR workaround) caused a regression. It added a check that the LCR was written properly to detect and workaround the busy quirk, but the behaviour of bit 5 (UART_LCR_SPAR) differs between IP versions 3.00a and 3.14c per the docs. On older versions this caused the check to fail and it would repeatedly force idle and rewrite the LCR register, causing delays and preventing any input from serial being received. This is fixed by masking out UART_LCR_SPAR before making the comparison. Signed-off-by: James Hogan <james.hogan@imgtec.com> Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org> Cc: Jiri Slaby <jslaby@suse.cz> Cc: Tim Kryger <tim.kryger@linaro.org> Cc: Ezequiel Garcia <ezequiel.garcia@free-electrons.com> Cc: Matt Porter <matt.porter@linaro.org> Cc: Markus Mayer <markus.mayer@linaro.org> Tested-by: Tim Kryger <tim.kryger@linaro.org> Tested-by: Ezequiel Garcia <ezequiel.garcia@free-electrons.com> Tested-by: Heikki Krogerus <heikki.krogerus@linux.intel.com> Cc: Wang Nan <wangnan0@huawei.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> 
commit 6979f8d28049879e6147767d93ba6732c8bd94f4 upstream.

Commit c49436b657d0 (serial: 8250_dw: Improve unwritable LCR workaround)
caused a regression. It added a check that the LCR was written properly
to detect and workaround the busy quirk, but the behaviour of bit 5
(UART_LCR_SPAR) differs between IP versions 3.00a and 3.14c per the
docs. On older versions this caused the check to fail and it would
repeatedly force idle and rewrite the LCR register, causing delays and
preventing any input from serial being received.

This is fixed by masking out UART_LCR_SPAR before making the comparison.

Signed-off-by: James Hogan <james.hogan@imgtec.com>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: Jiri Slaby <jslaby@suse.cz>
Cc: Tim Kryger <tim.kryger@linaro.org>
Cc: Ezequiel Garcia <ezequiel.garcia@free-electrons.com>
Cc: Matt Porter <matt.porter@linaro.org>
Cc: Markus Mayer <markus.mayer@linaro.org>
Tested-by: Tim Kryger <tim.kryger@linaro.org>
Tested-by: Ezequiel Garcia <ezequiel.garcia@free-electrons.com>
Tested-by: Heikki Krogerus <heikki.krogerus@linux.intel.com>
Cc: Wang Nan <wangnan0@huawei.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
serial: 8250_dw: Improve unwritable LCR workaround 2014-07-09T18:14:02+00:00 Tim Kryger tim.kryger@linaro.org 2013-10-01T17:18:08+00:00 6d5e79331417886196cb3a733bdb6645ba85bc42 commit c49436b657d0a56a6ad90d14a7c3041add7cf64d upstream. When configured with UART_16550_COMPATIBLE=NO or in versions prior to the introduction of this option, the Designware UART will ignore writes to the LCR if the UART is busy. The current workaround saves a copy of the last written LCR and re-writes it in the ISR for a special interrupt that is raised when a write was ignored. Unfortunately, interrupts are typically disabled prior to performing a sequence of register writes that include the LCR so the point at which the retry occurs is too late. An example is serial8250_do_set_termios() where an ignored LCR write results in the baud divisor not being set and instead a garbage character is sent out the transmitter. Furthermore, since serial_port_out() offers no way to indicate failure, a serious effort must be made to ensure that the LCR is actually updated before returning back to the caller. This is difficult, however, as a UART that was busy during the first attempt is likely to still be busy when a subsequent attempt is made unless some extra action is taken. This updated workaround reads back the LCR after each write to confirm that the new value was accepted by the hardware. Should the hardware ignore a write, the TX/RX FIFOs are cleared and the receive buffer read before attempting to rewrite the LCR out of the hope that doing so will force the UART into an idle state. While this may seem unnecessarily aggressive, writes to the LCR are used to change the baud rate, parity, stop bit, or data length so the data that may be lost is likely not important. Admittedly, this is far from ideal but it seems to be the best that can be done given the hardware limitations. Lastly, the revised workaround doesn't touch the LCR in the ISR, so it avoids the possibility of a "serial8250: too much work for irq" lock up. This problem is rare in real situations but can be reproduced easily by wiring up two UARTs and running the following commands. # stty -F /dev/ttyS1 echo # stty -F /dev/ttyS2 echo # cat /dev/ttyS1 & [1] 375 # echo asdf > /dev/ttyS1 asdf [ 27.700000] serial8250: too much work for irq96 [ 27.700000] serial8250: too much work for irq96 [ 27.710000] serial8250: too much work for irq96 [ 27.710000] serial8250: too much work for irq96 [ 27.720000] serial8250: too much work for irq96 [ 27.720000] serial8250: too much work for irq96 [ 27.730000] serial8250: too much work for irq96 [ 27.730000] serial8250: too much work for irq96 [ 27.740000] serial8250: too much work for irq96 Signed-off-by: Tim Kryger <tim.kryger@linaro.org> Reviewed-by: Matt Porter <matt.porter@linaro.org> Reviewed-by: Markus Mayer <markus.mayer@linaro.org> Reviewed-by: Heikki Krogerus <heikki.krogerus@linux.intel.com> [wangnan: backport to 3.10.43: - adjust context - remove unneeded local var] Signed-off-by: Wang Nan <wangnan0@huawei.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> 
commit c49436b657d0a56a6ad90d14a7c3041add7cf64d upstream.

When configured with UART_16550_COMPATIBLE=NO or in versions prior to
the introduction of this option, the Designware UART will ignore writes
to the LCR if the UART is busy.  The current workaround saves a copy of
the last written LCR and re-writes it in the ISR for a special interrupt
that is raised when a write was ignored.

Unfortunately, interrupts are typically disabled prior to performing a
sequence of register writes that include the LCR so the point at which
the retry occurs is too late.  An example is serial8250_do_set_termios()
where an ignored LCR write results in the baud divisor not being set and
instead a garbage character is sent out the transmitter.

Furthermore, since serial_port_out() offers no way to indicate failure,
a serious effort must be made to ensure that the LCR is actually updated
before returning back to the caller.  This is difficult, however, as a
UART that was busy during the first attempt is likely to still be busy
when a subsequent attempt is made unless some extra action is taken.

This updated workaround reads back the LCR after each write to confirm
that the new value was accepted by the hardware.  Should the hardware
ignore a write, the TX/RX FIFOs are cleared and the receive buffer read
before attempting to rewrite the LCR out of the hope that doing so will
force the UART into an idle state.  While this may seem unnecessarily
aggressive, writes to the LCR are used to change the baud rate, parity,
stop bit, or data length so the data that may be lost is likely not
important.  Admittedly, this is far from ideal but it seems to be the
best that can be done given the hardware limitations.

Lastly, the revised workaround doesn't touch the LCR in the ISR, so it
avoids the possibility of a "serial8250: too much work for irq" lock up.
This problem is rare in real situations but can be reproduced easily by
wiring up two UARTs and running the following commands.

  # stty -F /dev/ttyS1 echo
  # stty -F /dev/ttyS2 echo
  # cat /dev/ttyS1 &
  [1] 375
  # echo asdf > /dev/ttyS1
  asdf

  [   27.700000] serial8250: too much work for irq96
  [   27.700000] serial8250: too much work for irq96
  [   27.710000] serial8250: too much work for irq96
  [   27.710000] serial8250: too much work for irq96
  [   27.720000] serial8250: too much work for irq96
  [   27.720000] serial8250: too much work for irq96
  [   27.730000] serial8250: too much work for irq96
  [   27.730000] serial8250: too much work for irq96
  [   27.740000] serial8250: too much work for irq96

Signed-off-by: Tim Kryger <tim.kryger@linaro.org>
Reviewed-by: Matt Porter <matt.porter@linaro.org>
Reviewed-by: Markus Mayer <markus.mayer@linaro.org>
Reviewed-by: Heikki Krogerus <heikki.krogerus@linux.intel.com>
[wangnan: backport to 3.10.43:
  - adjust context
  - remove unneeded local var]
Signed-off-by: Wang Nan <wangnan0@huawei.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
serial: 8250_dw: Report CTS asserted for auto flow 2014-07-09T18:14:02+00:00 Tim Kryger tim.kryger@linaro.org 2013-08-16T20:50:15+00:00 b1338609edcc468e0d7cdaa8d4d05f57e9fafe94 commit 33acbb82695f84e9429c1f7fbdeb4588dea12ffa upstream. When a serial port is configured for RTS/CTS flow control, serial core will disable the transmitter if it observes CTS is de-asserted. This is perfectly reasonable and appropriate when the UART lacks the ability to automatically perform CTS flow control. However, if the UART hardware can manage flow control automatically, it is important that software not get involved. When the DesignWare UART enables 16C750 style auto-RTS/CTS it stops generating interrupts for changes in CTS state so software mostly stays out of the way. However, it does report the true state of CTS in the MSR so software may notice it is de-asserted and respond by improperly disabling the transmitter. Once this happens the transmitter will be blocked forever. To avoid this situation, we simply lie to the 8250 and serial core by reporting that CTS is asserted whenever auto-RTS/CTS mode is enabled. Signed-off-by: Tim Kryger <tim.kryger@linaro.org> Reviewed-by: Matt Porter <matt.porter@linaro.org> Reviewed-by: Markus Mayer <markus.mayer@linaro.org> Cc: Wang Nan <wangnan0@huawei.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> 
commit 33acbb82695f84e9429c1f7fbdeb4588dea12ffa upstream.

When a serial port is configured for RTS/CTS flow control, serial core
will disable the transmitter if it observes CTS is de-asserted. This is
perfectly reasonable and appropriate when the UART lacks the ability to
automatically perform CTS flow control.

However, if the UART hardware can manage flow control automatically, it
is important that software not get involved.  When the DesignWare UART
enables 16C750 style auto-RTS/CTS it stops generating interrupts for
changes in CTS state so software mostly stays out of the way.  However,
it does report the true state of CTS in the MSR so software may notice
it is de-asserted and respond by improperly disabling the transmitter.
Once this happens the transmitter will be blocked forever.

To avoid this situation, we simply lie to the 8250 and serial core by
reporting that CTS is asserted whenever auto-RTS/CTS mode is enabled.

Signed-off-by: Tim Kryger <tim.kryger@linaro.org>
Reviewed-by: Matt Porter <matt.porter@linaro.org>
Reviewed-by: Markus Mayer <markus.mayer@linaro.org>
Cc: Wang Nan <wangnan0@huawei.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
8250_core: Fix unwanted TX chars write 2014-06-07T20:25:30+00:00 Loic Poulain loic.poulain@intel.com 2014-04-24T09:38:56+00:00 b67e840cb1982f32217375ac992a21b343540cb9 commit b08c9c317e3f7764a91d522cd031639ba42b98cc upstream. On transmit-hold-register empty, serial8250_tx_chars should be called only if we don't use DMA. DMA has its own tx cycle. Signed-off-by: Loic Poulain <loic.poulain@intel.com> Reviewed-by: Heikki Krogerus <heikki.krogerus@linux.intel.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> 
commit b08c9c317e3f7764a91d522cd031639ba42b98cc upstream.

On transmit-hold-register empty, serial8250_tx_chars
should be called only if we don't use DMA.
DMA has its own tx cycle.

Signed-off-by: Loic Poulain <loic.poulain@intel.com>
Reviewed-by: Heikki Krogerus <heikki.krogerus@linux.intel.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
serial: 8250: Fix thread unsafe __dma_tx_complete function 2014-06-07T20:25:30+00:00 Loic Poulain loic.poulain@intel.com 2014-04-24T09:34:48+00:00 e179df5fd9250ae67f8e8fcb1e56a43ce820fcae commit f8fd1b0350d3a4581125f5eda6528f5a2c5f9183 upstream. __dma_tx_complete is not protected against concurrent call of serial8250_tx_dma. it can lead to circular tail index corruption or parallel call of serial_tx_dma on the same data portion. This patch fixes this issue by holding the port lock. Signed-off-by: Loic Poulain <loic.poulain@intel.com> Reviewed-by: Heikki Krogerus <heikki.krogerus@linux.intel.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> 
commit f8fd1b0350d3a4581125f5eda6528f5a2c5f9183 upstream.

__dma_tx_complete is not protected against concurrent
call of serial8250_tx_dma. it can lead to circular tail
index corruption or parallel call of serial_tx_dma on the
same data portion.

This patch fixes this issue by holding the port lock.

Signed-off-by: Loic Poulain <loic.poulain@intel.com>
Reviewed-by: Heikki Krogerus <heikki.krogerus@linux.intel.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>