From: Matthew Howell <mrhowel@xxxxxxxxxxxxx>
Sealevel XR17V35X based devices are inoperable on kernel versions
4.11 and above due to a change in the GPIO preconfiguration introduced in commit
7dea8165f1d. This patch fixes this by preconfiguring the GPIO on Sealevel
cards to the value (0x00) used prior to commit 7dea8165f1d
Fixes: 7dea8165f1d ("serial: exar: Preconfigure xr17v35x MPIOs as output")
Signed-off-by: Matthew Howell <mrhowel@xxxxxxxxxxxxx>
---
This is a revised patch submission based on comments received on
the previous submission.
See https://www.spinics.net/lists/linux-serial/msg39348.html
I am using a different email address to address the email footer issue,
and I have attempted to fix the formatting issues.
Summary/justification of the patch is below.
With GPIOs preconfigured as per commit 7dea8165f1d all ports on Sealevel
XR17V35X based devices become stuck in high impedance mode, regardless of
dip-switch or software configuration. This causes the device to become
effectively unusable. This patch (in various forms) has been distributed
to our customers and no issues related to it have been reported.
Let me know if any changes need to be made.
--- linux/drivers/tty/serial/8250/8250_exar.c.orig 2020-07-09 11:05:03.920060577 -0400
+++ linux/drivers/tty/serial/8250/8250_exar.c 2020-07-09 11:05:25.275891627 -0400
@@ -326,7 +326,7 @@ static void setup_gpio(struct pci_dev *p
* devices will export them as GPIOs, so we pre-configure them safely
* as inputs.
*/
- u8 dir = pcidev->vendor == PCI_VENDOR_ID_EXAR ? 0xff : 0x00;
+ u8 dir = (pcidev->vendor == PCI_VENDOR_ID_EXAR && pcidev->subsystem_vendor != PCI_VENDOR_ID_SEALEVEL) ? 0xff : 0x00;
writeb(0x00, p + UART_EXAR_MPIOINT_7_0);
writeb(0x00, p + UART_EXAR_MPIOLVL_7_0);
