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1aa4ad4e |
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10-Apr-2024 |
Tony Lindgren <tony@atomide.com> |
serial: core: Fix missing shutdown and startup for serial base port We are seeing start_tx being called after port shutdown as noted by Jiri. This happens because we are missing the startup and shutdown related functions for the serial base port. Let's fix the issue by adding startup and shutdown functions for the serial base port to block tx flushing for the serial base port when the port is not in use. Fixes: 84a9582fd203 ("serial: core: Start managing serial controllers to enable runtime PM") Cc: stable <stable@kernel.org> Reported-by: Jiri Slaby <jirislaby@kernel.org> Signed-off-by: Tony Lindgren <tony@atomide.com> Link: https://lore.kernel.org/r/20240411055848.38190-1-tony@atomide.com Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
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e894b600 |
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04-Mar-2024 |
Andy Shevchenko <andriy.shevchenko@linux.intel.com> |
serial: port: Introduce a common helper to read properties Several serial drivers want to read the same or similar set of the port properties. Make a common helper for them. Signed-off-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com> Link: https://lore.kernel.org/r/20240304123035.758700-4-andriy.shevchenko@linux.intel.com Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
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43066e32 |
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26-Feb-2024 |
Yicong Yang <yangyicong@hisilicon.com> |
serial: port: Don't suspend if the port is still busy We accidently met the issue that the bash prompt is not shown after the previous command done and until the next input if there's only one CPU (In our issue other CPUs are isolated by isolcpus=). Further analysis shows it's because the port entering runtime suspend even if there's still pending chars in the buffer and the pending chars will only be processed in next device resuming. We are using amba-pl011 and the problematic flow is like below: Bash kworker tty_write() file_tty_write() n_tty_write() uart_write() __uart_start() pm_runtime_get() // wakeup waker queue_work() pm_runtime_work() rpm_resume() status = RPM_RESUMING serial_port_runtime_resume() port->ops->start_tx() pl011_tx_chars() uart_write_wakeup() […] __uart_start() pm_runtime_get() < 0 // because runtime status = RPM_RESUMING // later data are not commit to the port driver status = RPM_ACTIVE rpm_idle() -> rpm_suspend() This patch tries to fix this by checking the port busy before entering runtime suspending. A runtime_suspend callback is added for the port driver. When entering runtime suspend the callback is invoked, if there's still pending chars in the buffer then flush the buffer. Fixes: 84a9582fd203 ("serial: core: Start managing serial controllers to enable runtime PM") Cc: stable <stable@kernel.org> Reviewed-by: Tony Lindgren <tony@atomide.com> Reviewed-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com> Signed-off-by: Yicong Yang <yangyicong@hisilicon.com> Link: https://lore.kernel.org/r/20240226152351.40924-1-yangyicong@huawei.com Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
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559c7ff4 |
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14-Sep-2023 |
Thomas Gleixner <tglx@linutronix.de> |
serial: core: Use port lock wrappers When a serial port is used for kernel console output, then all modifications to the UART registers which are done from other contexts, e.g. getty, termios, are interference points for the kernel console. So far this has been ignored and the printk output is based on the principle of hope. The rework of the console infrastructure which aims to support threaded and atomic consoles, requires to mark sections which modify the UART registers as unsafe. This allows the atomic write function to make informed decisions and eventually to restore operational state. It also allows to prevent the regular UART code from modifying UART registers while printk output is in progress. All modifications of UART registers are guarded by the UART port lock, which provides an obvious synchronization point with the console infrastructure. To avoid adding this functionality to all UART drivers, wrap the spin_[un]lock*() invocations for uart_port::lock into helper functions which just contain the spin_[un]lock*() invocations for now. In a subsequent step these helpers will gain the console synchronization mechanisms. Converted with coccinelle. No functional change. Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Signed-off-by: John Ogness <john.ogness@linutronix.de> Link: https://lore.kernel.org/r/20230914183831.587273-58-john.ogness@linutronix.de Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
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84a9582f |
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25-May-2023 |
Tony Lindgren <tony@atomide.com> |
serial: core: Start managing serial controllers to enable runtime PM We want to enable runtime PM for serial port device drivers in a generic way. To do this, we want to have the serial core layer manage the registered physical serial controller devices. To manage serial controllers, let's set up a struct bus and struct device for the serial core controller as suggested by Greg and Jiri. The serial core controller devices are children of the physical serial port device. The serial core controller device is needed to support multiple different kind of ports connected to single physical serial port device. Let's also set up a struct device for the serial core port. The serial core port instances are children of the serial core controller device. With the serial core port device we can now flush pending TX on the runtime PM resume as suggested by Johan. Suggested-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com> Suggested-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> Suggested-by: Jiri Slaby <jirislaby@kernel.org> Suggested-by: Johan Hovold <johan@kernel.org> Signed-off-by: Tony Lindgren <tony@atomide.com> Reviewed-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com> Link: https://lore.kernel.org/r/20230525113034.46880-1-tony@atomide.com Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
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