From bc02d15a3452fdf9276e8fb89c5e504a88df888a Mon Sep 17 00:00:00 2001 From: Dan Williams Date: Fri, 6 Apr 2012 11:49:50 -0700 Subject: serial/8250_pci: add a "force background timer" flag and use it for the "kt" serial port Workaround dropped notifications in the iir register. Register reads coincident with new interrupt notifications sometimes result in this device clearing the interrupt event without reporting it in the read data. The serial core already has a heuristic for determining when a device has an untrustworthy iir register. In this case when we apriori know that the iir is faulty use a flag (UPF_BUG_THRE) to bypass the test and force usage of the background timer. [stable: 3.3.x] Acked-by: Alan Cox Cc: stable Reported-by: Nhan H Mai Reported-by: Sudhakar Mamillapalli Tested-by: Nhan H Mai Tested-by: Sudhakar Mamillapalli Signed-off-by: Dan Williams Signed-off-by: Greg Kroah-Hartman --- drivers/tty/serial/8250/8250.c | 8 +++++--- drivers/tty/serial/8250/8250_pci.c | 17 ++++++++++++++++- 2 files changed, 21 insertions(+), 4 deletions(-) (limited to 'drivers/tty') diff --git a/drivers/tty/serial/8250/8250.c b/drivers/tty/serial/8250/8250.c index 56492d208a7a..5c27f7e6c9f1 100644 --- a/drivers/tty/serial/8250/8250.c +++ b/drivers/tty/serial/8250/8250.c @@ -2035,10 +2035,12 @@ static int serial8250_startup(struct uart_port *port) spin_unlock_irqrestore(&port->lock, flags); /* - * If the interrupt is not reasserted, setup a timer to - * kick the UART on a regular basis. + * If the interrupt is not reasserted, or we otherwise + * don't trust the iir, setup a timer to kick the UART + * on a regular basis. */ - if (!(iir1 & UART_IIR_NO_INT) && (iir & UART_IIR_NO_INT)) { + if ((!(iir1 & UART_IIR_NO_INT) && (iir & UART_IIR_NO_INT)) || + up->port.flags & UPF_BUG_THRE) { up->bugs |= UART_BUG_THRE; pr_debug("ttyS%d - using backup timer\n", serial_index(port)); diff --git a/drivers/tty/serial/8250/8250_pci.c b/drivers/tty/serial/8250/8250_pci.c index 105dcfbd3d33..858dca865d6a 100644 --- a/drivers/tty/serial/8250/8250_pci.c +++ b/drivers/tty/serial/8250/8250_pci.c @@ -1092,6 +1092,14 @@ static int skip_tx_en_setup(struct serial_private *priv, return pci_default_setup(priv, board, port, idx); } +static int kt_serial_setup(struct serial_private *priv, + const struct pciserial_board *board, + struct uart_port *port, int idx) +{ + port->flags |= UPF_BUG_THRE; + return skip_tx_en_setup(priv, board, port, idx); +} + static int pci_eg20t_init(struct pci_dev *dev) { #if defined(CONFIG_SERIAL_PCH_UART) || defined(CONFIG_SERIAL_PCH_UART_MODULE) @@ -1110,7 +1118,6 @@ pci_xr17c154_setup(struct serial_private *priv, return pci_default_setup(priv, board, port, idx); } -/* This should be in linux/pci_ids.h */ #define PCI_VENDOR_ID_SBSMODULARIO 0x124B #define PCI_SUBVENDOR_ID_SBSMODULARIO 0x124B #define PCI_DEVICE_ID_OCTPRO 0x0001 @@ -1140,6 +1147,7 @@ pci_xr17c154_setup(struct serial_private *priv, #define PCI_DEVICE_ID_OXSEMI_16PCI958 0x9538 #define PCIE_DEVICE_ID_NEO_2_OX_IBM 0x00F6 #define PCI_DEVICE_ID_PLX_CRONYX_OMEGA 0xc001 +#define PCI_DEVICE_ID_INTEL_PATSBURG_KT 0x1d3d /* Unknown vendors/cards - this should not be in linux/pci_ids.h */ #define PCI_SUBDEVICE_ID_UNKNOWN_0x1584 0x1584 @@ -1224,6 +1232,13 @@ static struct pci_serial_quirk pci_serial_quirks[] __refdata = { .subdevice = PCI_ANY_ID, .setup = ce4100_serial_setup, }, + { + .vendor = PCI_VENDOR_ID_INTEL, + .device = PCI_DEVICE_ID_INTEL_PATSBURG_KT, + .subvendor = PCI_ANY_ID, + .subdevice = PCI_ANY_ID, + .setup = kt_serial_setup, + }, /* * ITE */ -- cgit v1.2.3