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 | 4 +++-
drivers/tty/serial/8250_pci.c | 17 ++++++++++++++++-
include/linux/serial_core.h | 1 +
3 files changed, 20 insertions(+), 2 deletions(-)
diff --git a/drivers/tty/serial/8250.c b/drivers/tty/serial/8250.c
index eeadf1b..3a8e5bf 100644
--- a/drivers/tty/serial/8250.c
+++ b/drivers/tty/serial/8250.c
@@ -1619,11 +1619,13 @@ static irqreturn_t serial8250_interrupt(int irq, void *dev_id)
do {
struct uart_8250_port *up;
struct uart_port *port;
+ bool skip;
up = list_entry(l, struct uart_8250_port, list);
port = &up->port;
+ skip = pass_counter && up->port.flags & UPF_IIR_ONCE;
- if (port->handle_irq(port)) {
+ if (!skip && port->handle_irq(port)) {
handled = 1;
end = NULL;
} else if (end == NULL)
diff --git a/drivers/tty/serial/8250_pci.c b/drivers/tty/serial/8250_pci.c
index 825937a..8742ef5 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)
@@ -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
@@ -1136,6 +1143,7 @@ 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
@@ -1220,6 +1228,13 @@ 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/serial_core.h b/include/linux/serial_core.h
index 945e02c..b67305e 100644
--- a/include/linux/serial_core.h
+++ b/include/linux/serial_core.h
@@ -351,6 +351,7 @@ struct uart_port {
#define UPF_CONS_FLOW ((__force upf_t) (1 << 23))
#define UPF_SHARE_IRQ ((__force upf_t) (1 << 24))
#define UPF_EXAR_EFR ((__force upf_t) (1 << 25))
+#define UPF_IIR_ONCE ((__force upf_t) (1 << 26))
/* 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))
--
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