Re: [PATCH v4 00/14] serial: 8250: add Moxa MUEx50 PCIe board support

From: Jiri Slaby

Date: Thu Jul 30 2026 - 02:11:17 EST


On 29. 07. 26, 8:05, Crescent Hsieh wrote:
This series consolidates Moxa PCIe multiport serial board support under a
dedicated 8250_mxpcie driver and adds MUEx50 UART support needed by these
boards.

The first part splits the existing Moxa PCIe board handling out of
8250_pci into a separate driver while preserving the existing probe flow
and device IDs. The series then introduces the MUEx50 UART port type and
enables the board-specific UART setup, including enhanced mode and FIFO
trigger programming.

The driver adds hardware-assisted flow control support for MUEx50 UARTs,
including automatic RTS/CTS handling and XON/XOFF offload. It also adds a
custom IRQ path and uses the MUEx50 memory-mapped FIFO windows to improve
RX and TX data movement.

Later patches add serial interface mode switching, RS485 break handling,
and per-port private state for MUEx50-specific configuration. The driver
supports switching the serial interface mode through the RS485
configuration path, covering RS232, RS422, and RS485 modes supported by
the boards.

The final part extends 8250 core callbacks where needed so low-level
drivers can override break control and rx_trig_bytes handling. The
8250_mxpcie driver uses these hooks to implement RS485 break handling via
MUEx50 features and to expose the MUEx50 programmable RX trigger level
through the generic rx_trig_bytes sysfs interface.

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Changes in v4:

This looks very well from my POV, except the two nits. Thanks for this.

Let's see what others say ;).

--
js
suse labs