Oxford Semiconductor PCIe (Tornado) 950 serial port devices need to operate in the enhanced mode via the EFR register for the Divide-by-M N/8 baud rate generator prescaler to be used in their native UART mode. Otherwise the prescaler is fixed at 1 causing grossly incorrect baud rates to be programmed.
Accessing the EFR register requires 16550A features to have been probed for, so request this to happen regardless of SERIAL_8250_16550A_VARIANTS by setting UPF_FULL_PROBE in port flags.
Signed-off-by: Maciej W. Rozycki macro@orcam.me.uk Reported-by: Anders Blomdell anders.blomdell@control.lth.se Fixes: 366f6c955d4d ("serial: 8250: Add proper clock handling for OxSemi PCIe devices") Cc: stable@vger.kernel.org # v5.19+ --- No change from v1. --- drivers/tty/serial/8250/8250_pci.c | 5 +++++ 1 file changed, 5 insertions(+)
linux-serial-8250-oxsemi-efr.diff Index: linux-macro/drivers/tty/serial/8250/8250_pci.c =================================================================== --- linux-macro.orig/drivers/tty/serial/8250/8250_pci.c +++ linux-macro/drivers/tty/serial/8250/8250_pci.c @@ -1232,6 +1232,10 @@ static void pci_oxsemi_tornado_set_mctrl serial8250_do_set_mctrl(port, mctrl); }
+/* + * We require EFR features for clock programming, so set UPF_FULL_PROBE + * for full probing regardless of CONFIG_SERIAL_8250_16550A_VARIANTS setting. + */ static int pci_oxsemi_tornado_setup(struct serial_private *priv, const struct pciserial_board *board, struct uart_8250_port *up, int idx) @@ -1239,6 +1243,7 @@ static int pci_oxsemi_tornado_setup(stru struct pci_dev *dev = priv->dev;
if (pci_oxsemi_tornado_p(dev)) { + up->port.flags |= UPF_FULL_PROBE; up->port.get_divisor = pci_oxsemi_tornado_get_divisor; up->port.set_divisor = pci_oxsemi_tornado_set_divisor; up->port.set_mctrl = pci_oxsemi_tornado_set_mctrl;