Revert "serial/8250_pci: setup-quirk workaround for the kt serial controller"

This reverts commit 448ac154c957c4580531fa0c8f2045816fe2f0e7.

The semantic of UPF_IIR_ONCE is only guaranteed to workaround the race
condition in the kt serial's iir register if the only source of
interrupts is THRE (fifo-empty) events.  An modem status event at the
wrong time can again cause an iir read to drop the 'empty' status
leading to a hang.  So, revert this in preparation for using the
existing "I don't trust my iir register" workaround in the 8250 core
(UART_BUG_THRE).

[stable: 3.3.x]
Cc: stable <stable@vger.kernel.org>
Acked-by: Alan Cox <alan@linux.intel.com>
Cc: Sudhakar Mamillapalli <sudhakar@fb.com>
Reported-by: Nhan H Mai <nhan.h.mai@intel.com>
Signed-off-by: Dan Williams <dan.j.williams@intel.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

2 files changed, 2 insertions, 19 deletions

diff --git a/drivers/tty/serial/8250/8250.c b/drivers/tty/serial/8250/8250.c
index 5b149b466ec8..56492d208a7a 100644
--- a/drivers/tty/serial/8250/8250.c
+++ b/drivers/tty/serial/8250/8250.c
@@ -1572,13 +1572,11 @@ 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 (!skip && port->handle_irq(port)) {
+                if (port->handle_irq(port)) {
                         handled = 1;
                         end = NULL;
                 } else if (end == NULL)
diff --git a/drivers/tty/serial/8250/8250_pci.c b/drivers/tty/serial/8250/8250_pci.c
index 1d4ccf8c8874..105dcfbd3d33 100644
--- a/drivers/tty/serial/8250/8250_pci.c
+++ b/drivers/tty/serial/8250/8250_pci.c
@@ -1092,14 +1092,6 @@ 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)
@@ -1118,6 +1110,7 @@ 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
@@ -1147,7 +1140,6 @@ 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
@@ -1232,13 +1224,6 @@ 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
          */