kernel/linux.git/drivers/tty/serial, branch master

tty: serial: ip22zilog: Fix section mispatch warning

2026-04-02T13:59:56+00:00

ip22zilog_prepare() is now called by driver probe routine, so it shouldn't be in the __init section any longer. Fixes: 3fc36ae6abd2 ("tty: serial: ip22zilog: Use platform device for probing") Reported-by: kernel test robot Closes: https://lore.kernel.org/oe-kbuild-all/202604020945.c9jAvCPs-lkp@intel.com/ Signed-off-by: Thomas Bogendoerfer Link: https://patch.msgid.link/20260402102154.136620-1-tbogendoerfer@suse.de Signed-off-by: Greg Kroah-Hartman

serial: sh-sci: Add support for RZ/G3L RSCI

2026-03-30T15:36:58+00:00

Add support for RZ/G3L RSCI. The RSCI IP found on the RZ/G3L SoC is similar to RZ/G3E, but it has 3 clocks (2 module clocks + 1 external clock) instead of 6 clocks (5 module clocks + 1 external clock) on the RZ/G3E. Both RZ/G3L and RZ/G3E have a 32-bit FIFO, but RZ/G3L has a single TCLK with internal dividers, whereas the RZ/G3E has explicit clocks for TCLK and its dividers. Add a new port type RSCI_PORT_SCIF32_SINGLE_TCLK to handle this clock difference. Signed-off-by: Biju Das Reviewed-by: Geert Uytterhoeven Link: https://patch.msgid.link/20260312082708.98835-3-biju.das.jz@bp.renesas.com Signed-off-by: Greg Kroah-Hartman

tty: atmel_serial: update outdated reference to atmel_tasklet_func()

2026-03-30T15:36:45+00:00

The modem-status comparison that used irq_status_prev was moved from atmel_tasklet_func() into atmel_handle_status() in commit d033e82db9a5 ("tty/serial: at91: handle IRQ status more safely"). Update the comment accordingly. Assisted-by: unnamed:deepseek-v3.2 coccinelle Signed-off-by: Kexin Sun Link: https://patch.msgid.link/20260324024857.3244-1-kexinsun@smail.nju.edu.cn Signed-off-by: Greg Kroah-Hartman

serial: xilinx_uartps: Drop unused include

2026-03-30T15:36:34+00:00

This driver includes the legacy header but does not use any symbols from it. Drop the inclusion. Signed-off-by: Andy Shevchenko Link: https://patch.msgid.link/20260320220827.3237499-1-andriy.shevchenko@linux.intel.com Signed-off-by: Greg Kroah-Hartman

serial: qcom-geni: drop stray newline format specifier

2026-03-30T15:36:28+00:00

Drop the newline character from the middle of the printk message. This avoids breaking the message into two lines unnecessarily. Signed-off-by: Kathiravan Thirumoorthy Reviewed-by: Konrad Dybcio Link: https://patch.msgid.link/20260319-drop_stray_n-v1-1-37fb619538bb@oss.qualcomm.com Signed-off-by: Greg Kroah-Hartman

serial: 8250: loongson: Enable building on MIPS Loongson64

2026-03-30T15:36:20+00:00

Loongson 3A4000 is a MIPS-based Loongson64 CPU which also supports 8250_loongson (loongson-uart). Enable building on MIPS Loongson64 so that Loongson 3A4000 can benefit from it. Signed-off-by: Rong Zhang Reviewed-by: Jiaxun Yang Link: https://patch.msgid.link/20260315184301.412844-3-rongrong@oss.cipunited.com Signed-off-by: Greg Kroah-Hartman

serial: 8250_fintek: Add support for F81214E

2026-03-30T15:36:09+00:00

The F81214E is a LPC/eSPI to 2 UART Super I/O chip. Functionally, it is the same as the F81216E. The only difference is that the F81216E has 4 UART ports, whereas the F81214E has 2 UART ports. Signed-off-by: Ravi Rama Link: https://patch.msgid.link/20260313194731.2671-1-ravi.rama@nexthop.ai Signed-off-by: Greg Kroah-Hartman

Merge 7.0-rc5 into tty-next

2026-03-23T08:59:16+00:00

We need the tty/serial fixes in here as well. Signed-off-by: Greg Kroah-Hartman

serial: 8250_dw: Ensure BUSY is deasserted

2026-03-12T14:34:29+00:00

DW UART cannot write to LCR, DLL, and DLH while BUSY is asserted. Existance of BUSY depends on uart_16550_compatible, if UART HW is configured with it those registers can always be written. There currently is dw8250_force_idle() which attempts to achieve non-BUSY state by disabling FIFO, however, the solution is unreliable when Rx keeps getting more and more characters. Create a sequence of operations that ensures UART cannot keep BUSY asserted indefinitely. The new sequence relies on enabling loopback mode temporarily to prevent incoming Rx characters keeping UART BUSY. Ensure no Tx in ongoing while the UART is switches into the loopback mode (requires exporting serial8250_fifo_wait_for_lsr_thre() and adding DMA Tx pause/resume functions). According to tests performed by Adriana Nicolae , simply disabling FIFO or clearing FIFOs only once does not always ensure BUSY is deasserted but up to two tries may be needed. This could be related to ongoing Rx of a character (a guess, not known for sure). Therefore, retry FIFO clearing a few times (retry limit 4 is arbitrary number but using, e.g., p->fifosize seems overly large). Tests performed by others did not exhibit similar challenge but it does not seem harmful to leave the FIFO clearing loop in place for all DW UARTs with BUSY functionality. Use the new dw8250_idle_enter/exit() to do divisor writes and LCR writes. In case of plain LCR writes, opportunistically try to update LCR first and only invoke dw8250_idle_enter() if the write did not succeed (it has been observed that in practice most LCR writes do succeed without complications). This issue was first reported by qianfan Zhao who put lots of debugging effort into understanding the solution space. Fixes: c49436b657d0 ("serial: 8250_dw: Improve unwritable LCR workaround") Fixes: 7d4008ebb1c9 ("tty: add a DesignWare 8250 driver") Cc: stable Reported-by: qianfan Zhao Link: https://lore.kernel.org/linux-serial/289bb78a-7509-1c5c-2923-a04ed3b6487d@163.com/ Reported-by: Adriana Nicolae Link: https://lore.kernel.org/linux-serial/20250819182322.3451959-1-adriana@arista.com/ Reported-by: Bandal, Shankar Tested-by: Bandal, Shankar Tested-by: Murthy, Shanth Reviewed-by: Andy Shevchenko Signed-off-by: Ilpo Järvinen Link: https://patch.msgid.link/20260203171049.4353-8-ilpo.jarvinen@linux.intel.com Signed-off-by: Greg Kroah-Hartman

serial: 8250: Add late synchronize_irq() to shutdown to handle DW UART BUSY

2026-03-12T14:34:25+00:00

When DW UART is !uart_16550_compatible, it can indicate BUSY at any point (when under constant Rx pressure) unless a complex sequence of steps is performed. Any LCR write can run a foul with the condition that prevents writing LCR while the UART is BUSY, which triggers BUSY_DETECT interrupt that seems unmaskable using IER bits. Normal flow is that dw8250_handle_irq() handles BUSY_DETECT condition by reading USR register. This BUSY feature, however, breaks the assumptions made in serial8250_do_shutdown(), which runs synchronize_irq() after clearing IER and assumes no interrupts can occur after that point but then proceeds to update LCR, which on DW UART can trigger an interrupt. If serial8250_do_shutdown() releases the interrupt handler before the handler has run and processed the BUSY_DETECT condition by read the USR register, the IRQ is not deasserted resulting in interrupt storm that triggers "irq x: nobody cared" warning leading to disabling the IRQ. Add late synchronize_irq() into serial8250_do_shutdown() to ensure BUSY_DETECT from DW UART is handled before port's interrupt handler is released. Alternative would be to add DW UART specific shutdown function but it would mostly duplicate the generic code and the extra synchronize_irq() seems pretty harmless in serial8250_do_shutdown(). Fixes: 7d4008ebb1c9 ("tty: add a DesignWare 8250 driver") Cc: stable Reported-by: Bandal, Shankar Tested-by: Bandal, Shankar Tested-by: Murthy, Shanth Reviewed-by: Andy Shevchenko Signed-off-by: Ilpo Järvinen Link: https://patch.msgid.link/20260203171049.4353-7-ilpo.jarvinen@linux.intel.com Signed-off-by: Greg Kroah-Hartman