Workaround dropped notifications in the iir register. Prevent reads coincident with new interrupt notifications by reading the iir at most once per interrupt. Reported-by: Nhan H Mai <nhan.h.mai@xxxxxxxxx> Signed-off-by: Dan Williams <dan.j.williams@xxxxxxxxx> --- drivers/tty/serial/8250.c | 6 +++++- drivers/tty/serial/8250_pci.c | 15 +++++++++++++++ include/linux/pci_ids.h | 1 + include/linux/serial_core.h | 1 + 4 files changed, 22 insertions(+), 1 deletions(-) diff --git a/drivers/tty/serial/8250.c b/drivers/tty/serial/8250.c index 7f50999..513e728 100644 --- a/drivers/tty/serial/8250.c +++ b/drivers/tty/serial/8250.c @@ -1652,7 +1652,11 @@ static irqreturn_t serial8250_interrupt(int irq, void *dev_id) up = list_entry(l, struct uart_8250_port, list); - iir = serial_in(up, UART_IIR); + if (pass_counter && up->port.flags & UPF_IIR_ONCE) + iir = UART_IIR_NO_INT; + else + iir = serial_in(up, UART_IIR); + if (!(iir & UART_IIR_NO_INT)) { serial8250_handle_port(up); diff --git a/drivers/tty/serial/8250_pci.c b/drivers/tty/serial/8250_pci.c index 3abeca2..4ad2fb4 100644 --- a/drivers/tty/serial/8250_pci.c +++ b/drivers/tty/serial/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_IIR_ONCE; + 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) @@ -1211,6 +1219,13 @@ 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 */ diff --git a/include/linux/pci_ids.h b/include/linux/pci_ids.h index ae96bbe..ed80d75 100644 --- a/include/linux/pci_ids.h +++ b/include/linux/pci_ids.h @@ -2492,6 +2492,7 @@ #define PCI_DEVICE_ID_INTEL_IOAT 0x1a38 #define PCI_DEVICE_ID_INTEL_COUGARPOINT_LPC_MIN 0x1c41 #define PCI_DEVICE_ID_INTEL_COUGARPOINT_LPC_MAX 0x1c5f +#define PCI_DEVICE_ID_INTEL_PATSBURG_KT 0x1d3d #define PCI_DEVICE_ID_INTEL_PATSBURG_LPC_0 0x1d40 #define PCI_DEVICE_ID_INTEL_PATSBURG_LPC_1 0x1d41 #define PCI_DEVICE_ID_INTEL_PANTHERPOINT_XHCI 0x1e31 diff --git a/include/linux/serial_core.h b/include/linux/serial_core.h index a5c3114..a66484b3 100644 --- a/include/linux/serial_core.h +++ b/include/linux/serial_core.h @@ -350,6 +350,7 @@ struct uart_port { #define UPF_MAGIC_MULTIPLIER ((__force upf_t) (1 << 16)) #define UPF_CONS_FLOW ((__force upf_t) (1 << 23)) #define UPF_SHARE_IRQ ((__force upf_t) (1 << 24)) +#define UPF_IIR_ONCE ((__force upf_t) (1 << 25)) /* The exact UART type is known and should not be probed. */ #define UPF_FIXED_TYPE ((__force upf_t) (1 << 27)) #define UPF_BOOT_AUTOCONF ((__force upf_t) (1 << 28)) -- To unsubscribe from this list: send the line "unsubscribe linux-serial" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html