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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@icequake.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@icequake.net>
Signed-off-by: Dominik Brodowski <linux@dominikbrodowski.net>
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>
(cherry picked from commit 1e287196507c4272f7096ad4b4f10b1cf4b9d280)

Signed-off-by: Willy Tarreau <w@1wt.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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