linux-kernel - [ 26/75] Revert "serial/8250_pci: init-quirk msi support for kt serial controller"

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Message-Id: <20120419210305.343056810@linuxfoundation.org>
Date:	Thu, 19 Apr 2012 14:03:29 -0700
From:	Greg KH <gregkh@...uxfoundation.org>
To:	linux-kernel@...r.kernel.org, stable@...r.kernel.org
Cc:	torvalds@...ux-foundation.org, akpm@...ux-foundation.org,
	alan@...rguk.ukuu.org.uk, Alan Cox <alan@...ux.intel.com>,
	Sudhakar Mamillapalli <sudhakar@...com>,
	Nhan H Mai <nhan.h.mai@...el.com>,
	Dan Williams <dan.j.williams@...el.com>
Subject: [ 26/75] Revert "serial/8250_pci: init-quirk msi support for kt serial controller"

3.3-stable review patch.  If anyone has any objections, please let me know.

------------------

From: Dan Williams <dan.j.williams@...el.com>

commit 3579812373aba92b2f3b632bdf99329bc3c05d62 upstream.

This reverts commit e86ff4a63c9fdd875ba8492577cd1ad2252f525c.

This tried to enforce the semantics of one interrupt per iir read of the
THRE (transmit-hold empty) status, but events from other sources
(particularly modem status) defeat this guarantee.

This change also broke 8250_pci suspend/resume support as
pciserial_resume_ports() re-runs .init() quirks, but does not run
.exit() quirks in pciserial_suspend_ports() leading to reports like:

  sysfs: cannot create duplicate filename '/devices/pci0000:00/0000:00:16.3/msi_irqs'

...and a subsequent crash.  The mismatch of init/exit at suspend/resume
seems like a bug in its own right.

Acked-by: Alan Cox <alan@...ux.intel.com>
Cc: Sudhakar Mamillapalli <sudhakar@...com>
Reported-by: Nhan H Mai <nhan.h.mai@...el.com>
Signed-off-by: Dan Williams <dan.j.williams@...el.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@...uxfoundation.org>

---
 drivers/tty/serial/8250/8250_pci.c |   14 --------------
 1 file changed, 14 deletions(-)

--- a/drivers/tty/serial/8250/8250_pci.c
+++ b/drivers/tty/serial/8250/8250_pci.c
@@ -1118,18 +1118,6 @@ pci_xr17c154_setup(struct serial_private
 	return pci_default_setup(priv, board, port, idx);
 }
 
-static int try_enable_msi(struct pci_dev *dev)
-{
-	/* use msi if available, but fallback to legacy otherwise */
-	pci_enable_msi(dev);
-	return 0;
-}
-
-static void disable_msi(struct pci_dev *dev)
-{
-	pci_disable_msi(dev);
-}
-
 #define PCI_VENDOR_ID_SBSMODULARIO	0x124B
 #define PCI_SUBVENDOR_ID_SBSMODULARIO	0x124B
 #define PCI_DEVICE_ID_OCTPRO		0x0001
@@ -1249,9 +1237,7 @@ static struct pci_serial_quirk pci_seria
 		.device		= PCI_DEVICE_ID_INTEL_PATSBURG_KT,
 		.subvendor	= PCI_ANY_ID,
 		.subdevice	= PCI_ANY_ID,
-		.init		= try_enable_msi,
 		.setup		= kt_serial_setup,
-		.exit		= disable_msi,
 	},
 	/*
 	 * ITE


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