kernel/linux.git/drivers/tty/serial, branch v6.13.6

serial: sh-sci: Increment the runtime usage counter for the earlycon device

2025-02-27T12:34:12+00:00

[ Upstream commit 651dee03696e1dfde6d9a7e8664bbdcd9a10ea7f ] In the sh-sci driver, serial ports are mapped to the sci_ports[] array, with earlycon mapped at index zero. The uart_add_one_port() function eventually calls __device_attach(), which, in turn, calls pm_request_idle(). The identified code path is as follows: uart_add_one_port() -> serial_ctrl_register_port() -> serial_core_register_port() -> serial_core_port_device_add() -> serial_base_port_add() -> device_add() -> bus_probe_device() -> device_initial_probe() -> __device_attach() -> // ... if (dev->p->dead) { // ... } else if (dev->driver) { // ... } else { // ... pm_request_idle(dev); // ... } The earlycon device clocks are enabled by the bootloader. However, the pm_request_idle() call in __device_attach() disables the SCI port clocks while earlycon is still active. The earlycon write function, serial_console_write(), calls sci_poll_put_char() via serial_console_putchar(). If the SCI port clocks are disabled, writing to earlycon may sometimes cause the SR.TDFE bit to remain unset indefinitely, causing the while loop in sci_poll_put_char() to never exit. On single-core SoCs, this can result in the system being blocked during boot when this issue occurs. To resolve this, increment the runtime PM usage counter for the earlycon SCI device before registering the UART port. Fixes: 0b0cced19ab1 ("serial: sh-sci: Add CONFIG_SERIAL_EARLYCON support") Cc: stable@vger.kernel.org Signed-off-by: Claudiu Beznea Link: https://lore.kernel.org/r/20250116182249.3828577-6-claudiu.beznea.uj@bp.renesas.com Signed-off-by: Greg Kroah-Hartman Signed-off-by: Sasha Levin

serial: sh-sci: Clean sci_ports[0] after at earlycon exit

2025-02-27T12:34:12+00:00

[ Upstream commit 5f1017069933489add0c08659673443c9905659e ] The early_console_setup() function initializes sci_ports[0].port with an object of type struct uart_port obtained from the struct earlycon_device passed as an argument to early_console_setup(). Later, during serial port probing, the serial port used as earlycon (e.g., port A) might be remapped to a different position in the sci_ports[] array, and a different serial port (e.g., port B) might be assigned to slot 0. For example: sci_ports[0] = port B sci_ports[X] = port A In this scenario, the new port mapped at index zero (port B) retains the data associated with the earlycon configuration. Consequently, after the Linux boot process, any access to the serial port now mapped to sci_ports[0] (port B) will block the original earlycon port (port A). To address this, introduce an early_console_exit() function to clean up sci_ports[0] when earlycon is exited. To prevent the cleanup of sci_ports[0] while the serial device is still being used by earlycon, introduce the struct sci_port::probing flag and account for it in early_console_exit(). Fixes: 0b0cced19ab1 ("serial: sh-sci: Add CONFIG_SERIAL_EARLYCON support") Cc: stable@vger.kernel.org Signed-off-by: Claudiu Beznea Link: https://lore.kernel.org/r/20250116182249.3828577-5-claudiu.beznea.uj@bp.renesas.com Signed-off-by: Greg Kroah-Hartman Stable-dep-of: 651dee03696e ("serial: sh-sci: Increment the runtime usage counter for the earlycon device") Signed-off-by: Sasha Levin

serial: sh-sci: Move runtime PM enable to sci_probe_single()

2025-02-27T12:34:12+00:00

[ Upstream commit 239f11209e5f282e16f5241b99256e25dd0614b6 ] Relocate the runtime PM enable operation to sci_probe_single(). This change prepares the codebase for upcoming fixes. While at it, replace the existing logic with a direct call to devm_pm_runtime_enable() and remove sci_cleanup_single(). The devm_pm_runtime_enable() function automatically handles disabling runtime PM during driver removal. Reviewed-by: Geert Uytterhoeven Signed-off-by: Claudiu Beznea Link: https://lore.kernel.org/r/20250116182249.3828577-3-claudiu.beznea.uj@bp.renesas.com Signed-off-by: Greg Kroah-Hartman Stable-dep-of: 651dee03696e ("serial: sh-sci: Increment the runtime usage counter for the earlycon device") Signed-off-by: Sasha Levin

serial: 8250: Fix fifo underflow on flush

2025-02-21T13:11:06+00:00

commit 9e512eaaf8f4008c44ede3dfc0fbc9d9c5118583 upstream. When flushing the serial port's buffer, uart_flush_buffer() calls kfifo_reset() but if there is an outstanding DMA transfer then the completion function will consume data from the kfifo via uart_xmit_advance(), underflowing and leading to ongoing DMA as the driver tries to transmit another 2^32 bytes. This is readily reproduced with serial-generic and amidi sending even short messages as closing the device on exit will wait for the fifo to drain and in the underflow case amidi hangs for 30 seconds on exit in tty_wait_until_sent(). A trace of that gives: kworker/1:1-84 [001] 51.769423: bprint: serial8250_tx_dma: tx_size=3 fifo_len=3 amidi-763 [001] 51.769460: bprint: uart_flush_buffer: resetting fifo irq/21-fe530000-76 [000] 51.769474: bprint: __dma_tx_complete: tx_size=3 irq/21-fe530000-76 [000] 51.769479: bprint: serial8250_tx_dma: tx_size=4096 fifo_len=4294967293 irq/21-fe530000-76 [000] 51.781295: bprint: __dma_tx_complete: tx_size=4096 irq/21-fe530000-76 [000] 51.781301: bprint: serial8250_tx_dma: tx_size=4096 fifo_len=4294963197 irq/21-fe530000-76 [000] 51.793131: bprint: __dma_tx_complete: tx_size=4096 irq/21-fe530000-76 [000] 51.793135: bprint: serial8250_tx_dma: tx_size=4096 fifo_len=4294959101 irq/21-fe530000-76 [000] 51.804949: bprint: __dma_tx_complete: tx_size=4096 Since the port lock is held in when the kfifo is reset in uart_flush_buffer() and in __dma_tx_complete(), adding a flush_buffer hook to adjust the outstanding DMA byte count is sufficient to avoid the kfifo underflow. Fixes: 9ee4b83e51f74 ("serial: 8250: Add support for dmaengine") Cc: stable Signed-off-by: John Keeping Link: https://lore.kernel.org/r/20250208124148.1189191-1-jkeeping@inmusicbrands.com Signed-off-by: Greg Kroah-Hartman

serial: port: Always update ->iotype in __uart_read_properties()

2025-02-21T13:11:06+00:00

commit e8486bd50ecf63c9a1e25271f258a8d959f2672f upstream. The documentation of the __uart_read_properties() states that ->iotype member is always altered after the function call, but the code doesn't do that in the case when use_defaults == false and the value of reg-io-width is unsupported. Make sure the code follows the documentation. Note, the current users of the uart_read_and_validate_port_properties() will fail and the change doesn't affect their behaviour, neither users of uart_read_port_properties() will be affected since the alteration happens there even in the current code flow. Fixes: e894b6005dce ("serial: port: Introduce a common helper to read properties") Cc: stable Signed-off-by: Andy Shevchenko Link: https://lore.kernel.org/r/20250124161530.398361-3-andriy.shevchenko@linux.intel.com Signed-off-by: Greg Kroah-Hartman

serial: port: Assign ->iotype correctly when ->iobase is set

2025-02-21T13:11:06+00:00

commit 166ac2bba167d575e7146beaa66093bc7c072f43 upstream. Currently the ->iotype is always assigned to the UPIO_MEM when the respective property is not found. However, this will not support the cases when user wants to have UPIO_PORT to be set or preserved. Support this scenario by checking ->iobase value and default the ->iotype respectively. Fixes: 1117a6fdc7c1 ("serial: 8250_of: Switch to use uart_read_port_properties()") Fixes: e894b6005dce ("serial: port: Introduce a common helper to read properties") Cc: stable Signed-off-by: Andy Shevchenko Link: https://lore.kernel.org/r/20250124161530.398361-2-andriy.shevchenko@linux.intel.com Signed-off-by: Greg Kroah-Hartman

8250: microchip: pci1xxxx: Add workaround for RTS bit toggle

2025-02-21T13:10:56+00:00

[ Upstream commit e95cb63e57381f00d9274533ea7fd0ac3bf4e5b0 ] In the B0 revision, the RTS pin remains high due to incorrect hardware mapping. To address this issue, enable auto-direction control with the RTS bit in ADCL_CFG_REG. This configuration ensures that the RTS pin goes low when the terminal is opened and high when the terminal is closed. Additionally, we reset the step counter for Rx and Tx engines by writing into FRAC_DIV_CFG_REG. Signed-off-by: Rengarajan S Link: https://lore.kernel.org/r/20241218094017.18290-1-rengarajan.s@microchip.com Signed-off-by: Greg Kroah-Hartman Signed-off-by: Sasha Levin

serial: 8250_pci: Share WCH IDs with parport_serial driver

2025-02-21T13:10:55+00:00

[ Upstream commit 535a07698b8b3e6f305673102d297262cae2360a ] parport_serial driver uses subset of WCH IDs that are present in 8250_pci. Share them via pci_ids.h and switch parport_serial to use defined constants. Signed-off-by: Andy Shevchenko Link: https://lore.kernel.org/r/20241204031114.1029882-3-andriy.shevchenko@linux.intel.com Signed-off-by: Greg Kroah-Hartman Signed-off-by: Sasha Levin

serial: 8250_pci: Resolve WCH vendor ID ambiguity

2025-02-21T13:10:55+00:00

[ Upstream commit 16076ca3a1565491bcb28689e555d569a39391c7 ] There are two sites of the same brand: wch.cn and wch-ic.com. They are property of the same company, but it appears that they managed to get two different PCI vendor IDs. Rename them accordingly using standard pattern, i.e. PCI_VENDOR_ID_... While at it, move to PCI_VDEVICE() in the ID tables. Signed-off-by: Andy Shevchenko Link: https://lore.kernel.org/r/20241204031114.1029882-2-andriy.shevchenko@linux.intel.com Signed-off-by: Greg Kroah-Hartman Signed-off-by: Sasha Levin

serial: sh-sci: Do not probe the serial port if its slot in sci_ports[] is in use

2025-02-17T10:36:31+00:00

commit 9f7dea875cc7f9c1a56a5c688290634a59cd1420 upstream. In the sh-sci driver, sci_ports[0] is used by earlycon. If the earlycon is still active when sci_probe() is called and the new serial port is supposed to map to sci_ports[0], return -EBUSY to prevent breaking the earlycon. This situation should occurs in debug scenarios, and users should be aware of the potential conflict. Fixes: 0b0cced19ab1 ("serial: sh-sci: Add CONFIG_SERIAL_EARLYCON support") Cc: stable@vger.kernel.org Signed-off-by: Claudiu Beznea Link: https://lore.kernel.org/r/20250116182249.3828577-4-claudiu.beznea.uj@bp.renesas.com Signed-off-by: Greg Kroah-Hartman Signed-off-by: Greg Kroah-Hartman