On Wed, Apr 03, 2024 at 03:41:30PM +0800, Guanbing Huang wrote: > From: Guanbing Huang <albanhuang@xxxxxxxxxxx> > > The 16550a serial port based on the ACPI table requires obtaining the > reg-shift attribute. In the ACPI scenario, If the reg-shift property > is not configured like in DTS, the 16550a serial driver cannot read or > write controller registers properly during initialization. ... > uart.port.mapbase = pnp_mem_start(dev, 0); > + uart.port.mapsize = pnp_mem_end(dev, 0) - pnp_mem_start(dev, 0); pnp_mem_len() ... Add a comment here to explain that /* * The previous call may not set iotype correctly when reg-io-width * property is absent and it doesn't support IO port resource. */ > + uart.port.iotype = iotype; > uart.port.flags |= UPF_SKIP_TEST | UPF_BOOT_AUTOCONF; > if (pnp_irq_flags(dev, 0) & IORESOURCE_IRQ_SHAREABLE) > uart.port.flags |= UPF_SHARE_IRQ; > - uart.port.uartclk = 1843200; > - device_property_read_u32(&dev->dev, "clock-frequency", &uart.port.uartclk); > - uart.port.dev = &dev->dev; > + else > + uart.port.flags &= ~UPF_SHARE_IRQ; This is not needed, just move uart.port.flags |= UPF_SKIP_TEST | UPF_BOOT_AUTOCONF; to be before uart_read_properties(). -- With Best Regards, Andy Shevchenko