linux.git/drivers/tty/serial/imx.c, branch v4.3

Revert "serial: imx: remove unbalanced clk_prepare"

2015-10-04T17:51:42+00:00

This reverts commit 9e7b399d6528eac33a6fbfceb2b92af209c3454d.

Commit ("9e7b399d6528ea") causes the following warning and sometimes
also hangs the system:

------------[ cut here ]------------
 WARNING: CPU: 0 PID: 0 at kernel/locking/mutex.c:868 mutex_trylock+0x20c/0x22c()
 DEBUG_LOCKS_WARN_ON(in_interrupt())
 Modules linked in:
CPU: 0 PID: 0 Comm: swapper/0 Not tainted 4.2.0-rc7-next-20150818-00001-g14418a6 #4
Hardware name: Freescale i.MX6 Quad/DualLite (Device Tree)
Backtrace:
[<80012f08>] (dump_backtrace) from [<800130a4>] (show_stack+0x18/0x1c)
r6:00000364 r5:00000000 r4:00000000 r3:00000000
[<8001308c>] (show_stack) from [<807902b8>] (dump_stack+0x88/0xa4)
[<80790230>] (dump_stack) from [<8002a604>] (warn_slowpath_common+0x80/0xbc)
r5:807945c4 r4:80ab3b50
[<8002a584>] (warn_slowpath_common) from [<8002a6e4>] (warn_slowpath_fmt+0x38/0x40)
r8:00000000 r7:8131100c r6:8054c3cc r5:8131300c r4:80b0a570
[<8002a6b0>] (warn_slowpath_fmt) from [<807945c4>] (mutex_trylock+0x20c/0x22c)
r3:8095d0d8 r2:8095ab28
[<807943b8>] (mutex_trylock) from [<8054c3cc>] (clk_prepare_lock+0x14/0xf4)
r7:8131100c r6:be3f0c80 r5:00000037 r4:be3f0c80
[<8054c3b8>] (clk_prepare_lock) from [<8054dbfc>] (clk_prepare+0x18/0x30)
r5:00000037 r4:be3f0c80
[<8054dbe4>] (clk_prepare) from [<8036a600>] (imx_console_write+0x30/0x244)
r4:812d0bc8 r3:8132b9a4

To reproduce the problem we only need to let the board idle for something
like 30 seconds.

Tested on a imx6q-sabresd.

Signed-off-by: Fabio Estevam 
Reviewed-by: Eduardo Valentin 
Signed-off-by: Greg Kroah-Hartman

serial: imx: save and restore context in the suspend path

2015-08-15T00:23:25+00:00

This change teaches the imx serial driver to save its
context and restore it across suspend and resume path.
To do so, it introduces serial_imx_restore_context()
and serial_imx_save_context() functions. They use
a shadow set of registers to save key registers
and restore them accordingly. These functions can
be reused on other situations, when the device
context is lost.

Cc: Fabio Estevam 
Cc: Greg Kroah-Hartman 
Cc: Jiri Slaby 
Cc: linux-serial@vger.kernel.org
Cc: linux-kernel@vger.kernel.org
Signed-off-by: Eduardo Valentin 
Signed-off-by: Greg Kroah-Hartman

serial: imx: allow waking up on RTSD

2015-08-15T00:23:25+00:00

This patch sets RTSDEN bit when going into idle (Stop mode).
We add the RTSDEN for the case RTS is sent from
the remote connection. This way we allow the system
to wakeup when RTS is received.

Cc: Fabio Stevam 
Cc: Greg Kroah-Hartman 
Cc: Jiri Slaby 
Cc: linux-serial@vger.kernel.org
Cc: linux-kernel@vger.kernel.org
Signed-off-by: Eduardo Valentin 
Signed-off-by: Greg Kroah-Hartman

serial: imx: introduce serial_imx_enable_wakeup()

2015-08-15T00:23:25+00:00

This change is a code reorganization. Here we introduce
serial_imx_enable_wakeup() helper function to do
the job of configuring and preparing wakeup sources
on imx serial device. The idea is to allow other
parts of the code to call this function whenever
the device is known to go to idle.

Cc: Fabio Estevam 
Cc: Greg Kroah-Hartman 
Cc: Jiri Slaby 
Cc: linux-serial@vger.kernel.org
Cc: linux-kernel@vger.kernel.org
Signed-off-by: Eduardo Valentin 
Signed-off-by: Greg Kroah-Hartman

serial: imx: remove unbalanced clk_prepare

2015-08-15T00:23:25+00:00

The current code attempts to prepare clk_per and clk_ipg
before using the device. However, the result is an extra
prepare call on each clock. Here is the output of uart
clocks (only uart enabled and used as console):

$  grep uart /sys/kernel/debug/clk/clk_summary
 uart_serial           1            2    80000000          0 0
       uart           1            2    66000000          0 0

This patch balances the calls of prepares. The result is:

$  grep uart /sys/kernel/debug/clk/clk_summary
 uart_serial           1            1    80000000          0 0
       uart           1            1    66000000          0 0

Cc: Fabio Estevam 
Cc: Greg Kroah-Hartman 
Cc: Jiri Slaby 
Cc: linux-serial@vger.kernel.org
Cc: linux-pm@vger.kernel.org
Cc: linux-kernel@vger.kernel.org
Signed-off-by: Eduardo Valentin 
Signed-off-by: Greg Kroah-Hartman

Serial: imx: add dev_pm_ops to support suspend to ram/disk

2015-08-03T22:51:19+00:00

When system goes into low power states like SUSPEND_MEM and
HIBERNATION, the hardware IP block may be powered off to reduce
the power consumption. This power down may cause problems on
some imx platforms, because the hardware settings are reset to
its power on default values which may differ from the ones when
it power off. This patch added the dev_pm_ops and implemented
two callbacks: suspend_noirq and resume_noirq, which will save
the necessory hardware parameters right before power down and
recover them before system uses the hardware.

Because added the dev_pm_ops, the old suspend/resume callbacks
under platform_driver will not be called any more. Changed their
prototypes and moved those two callbacks into dev_pm_ops too.

Signed-off-by: Shenwei Wang 
Signed-off-by: Greg Kroah-Hartman

Revert "tty: serial: imx.c: Reset UART before activating interrupts"

2015-07-27T18:26:56+00:00

This reverts commit e95044ba4fee93f5ea8a1a24b2d921e148503833.

Commit e95044ba4fee93 ("tty: serial: imx.c: Reset UART before activating
interrupts") terribly messes up with the console on mx6 boards, so
let's revert it.

Reported-by: kernelci.org bot 
Cc: David Jander 
Signed-off-by: Fabio Estevam 
Signed-off-by: Greg Kroah-Hartman

Merge 4.2-rc4 into tty-next

2015-07-27T18:12:39+00:00

Other serial driver work wants to build on patches now in 4.2-rc4 so
merge the branch so this can properly happen.

Signed-off-by: Greg Kroah-Hartman

Revert "serial: imx: initialized DMA w/o HW flow enabled"

2015-07-24T00:40:14+00:00

This reverts commit 068500e08dc87ea9a453cc4a500cf3ab28d0f936.

According to some tests, SDMA support is broken at least for i.MX6 without
HW flow control. Different forms of data-corruption appear either with
the ROM firmware for the SDMA controller as well as when loading Freescale
provided SDMA firmware versions 1.1 or 3.1.

Signed-off-by: David Jander 
Cc: stable 
Signed-off-by: Greg Kroah-Hartman

tty: serial: imx.c: Reset UART before activating interrupts

2015-07-24T00:39:08+00:00

If the UART has been in use before this driver was loaded, IRQs might be
active and get fired as soon as we set the handler, which will crash
in the spin_lock_irqsave(&sport->port.lock, flags) because port.lock is
not initialized until the port is added at the end of probe.

Signed-off-by: David Jander 
Signed-off-by: Greg Kroah-Hartman