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serial: exar: Fix GPIO configuration for Sealevel cards based on XR17V35X

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Sealevel XR17V35X based devices are inoperable on kernel versions
4.11 and above due to a change in the GPIO preconfiguration introduced in
commit
7dea8165f1. This patch fixes this by preconfiguring the GPIO on Sealevel
cards to the value (0x00) used prior to commit 7dea8165f1

With GPIOs preconfigured as per commit 7dea8165f1 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.

Fixes: 7dea8165f1 ("serial: exar: Preconfigure xr17v35x MPIOs as output")
Signed-off-by: Matthew Howell <matthew.howell@sealevel.com>
Link: https://lore.kernel.org/r/alpine.DEB.2.21.2007221605270.13247@tstest-VirtualBox
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
This commit is contained in:
Matthew Howell 2020-07-22 16:11:24 -04:00 committed by Greg Kroah-Hartman
parent 033724d686
commit 5fdbe136ae
1 changed files with 11 additions and 1 deletions
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12
drivers/tty/serial/8250/8250_exar.c
View File

@ -326,7 +326,17 @@ static void setup_gpio(struct pci_dev *pcidev, u8 __iomem *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 = 0x00;
if ((pcidev->vendor == PCI_VENDOR_ID_EXAR) &&
(pcidev->subsystem_vendor != PCI_VENDOR_ID_SEALEVEL)) {
// Configure GPIO as inputs for Commtech adapters
dir = 0xff;
} else {
// Configure GPIO as outputs for SeaLevel adapters
dir = 0x00;
}
writeb(0x00, p + UART_EXAR_MPIOINT_7_0);
writeb(0x00, p + UART_EXAR_MPIOLVL_7_0);