linux-kernel - [PATCH 2.6.32 46/62] Disable write buffering on Toshiba ToPIC95

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Message-Id: <20150912225608.550098137@1wt.eu>
Date:	Sun, 13 Sep 2015 00:56:52 +0200
From:	Willy Tarreau <w@....eu>
To:	linux-kernel@...r.kernel.org, stable@...r.kernel.org
Cc:	"Ryan C. Underwood" <nemesis@...quake.net>,
	Dominik Brodowski <linux@...inikbrodowski.net>,
	Ben Hutchings <ben@...adent.org.uk>, Willy Tarreau <w@....eu>
Subject: [PATCH 2.6.32 46/62] Disable write buffering on Toshiba ToPIC95

2.6.32-longterm review patch.  If anyone has any objections, please let me know.

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

From: Ryan Underwood <nemesis@...quake.net>

commit 2fb22a8042fe96b4220843f79241c116d90922c4 upstream.

Disable write buffering on the Toshiba ToPIC95 if it is enabled by
somebody (it is not supposed to be a power-on default according to
the datasheet). On the ToPIC95, practically no 32-bit Cardbus card
will work under heavy load without locking up the whole system if
this is left enabled. I tried about a dozen. It does not affect
16-bit cards. This is similar to the O2 bugs in early controller
revisions it seems.

Bugzilla: https://bugzilla.kernel.org/show_bug.cgi?id=55961
Signed-off-by: Ryan C. Underwood <nemesis@...quake.net>
Signed-off-by: Dominik Brodowski <linux@...inikbrodowski.net>
Signed-off-by: Ben Hutchings <ben@...adent.org.uk>
(cherry picked from commit 1e287196507c4272f7096ad4b4f10b1cf4b9d280)

Signed-off-by: Willy Tarreau <w@....eu>
---
 drivers/pcmcia/topic.h | 16 ++++++++++++++++
 1 file changed, 16 insertions(+)

diff --git a/drivers/pcmcia/topic.h b/drivers/pcmcia/topic.h
index edccfa5..998a2a2 100644
--- a/drivers/pcmcia/topic.h
+++ b/drivers/pcmcia/topic.h
@@ -104,6 +104,9 @@
 #define TOPIC_EXCA_IF_CONTROL		0x3e	/* 8 bit */
 #define TOPIC_EXCA_IFC_33V_ENA		0x01
 
+#define TOPIC_PCI_CFG_PPBCN		0x3e	/* 16-bit */
+#define TOPIC_PCI_CFG_PPBCN_WBEN	0x0400
+
 static void topic97_zoom_video(struct pcmcia_socket *sock, int onoff)
 {
 	struct yenta_socket *socket = container_of(sock, struct yenta_socket, socket);
@@ -143,6 +146,7 @@ static int topic97_override(struct yenta_socket *socket)
 static int topic95_override(struct yenta_socket *socket)
 {
 	u8 fctrl;
+	u16 ppbcn;
 
 	/* enable 3.3V support for 16bit cards */
 	fctrl = exca_readb(socket, TOPIC_EXCA_IF_CONTROL);
@@ -151,6 +155,18 @@ static int topic95_override(struct yenta_socket *socket)
 	/* tell yenta to use exca registers to power 16bit cards */
 	socket->flags |= YENTA_16BIT_POWER_EXCA | YENTA_16BIT_POWER_DF;
 
+	/* Disable write buffers to prevent lockups under load with numerous
+	   Cardbus cards, observed on Tecra 500CDT and reported elsewhere on the
+	   net.  This is not a power-on default according to the datasheet
+	   but some BIOSes seem to set it. */
+	if (pci_read_config_word(socket->dev, TOPIC_PCI_CFG_PPBCN, &ppbcn) == 0
+	    && socket->dev->revision <= 7
+	    && (ppbcn & TOPIC_PCI_CFG_PPBCN_WBEN)) {
+		ppbcn &= ~TOPIC_PCI_CFG_PPBCN_WBEN;
+		pci_write_config_word(socket->dev, TOPIC_PCI_CFG_PPBCN, ppbcn);
+		dev_info(&socket->dev->dev, "Disabled ToPIC95 Cardbus write buffers.\n");
+	}
+
 	return 0;
 }
 
-- 
1.7.12.2.21.g234cd45.dirty



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