linux-kernel - [PATCH] [OLPC] sdhci: add quirk for the Marvell CaFe's interrupt timeout

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Message-ID: <20080623101352.3bbaf5b0@xo-debian>
Date:	Mon, 23 Jun 2008 10:13:52 -0400
From:	Andres Salomon <dilinger@...ued.net>
To:	akpm@...ux-foundation.org
Cc:	drzeus-sdhci@...eus.cx, sdhci-devel@...t.drzeus.cx,
	linux-kernel@...r.kernel.org
Subject: [PATCH] [OLPC] sdhci: add quirk for the Marvell CaFe's interrupt
 timeout


The CaFe chip has a hardware bug that ends up with us getting a timeout
value that's too small, causing the following sorts of problems:

[   60.525138] mmcblk0: error -110 transferring data
[   60.531477] end_request: I/O error, dev mmcblk0, sector 1484353
[   60.533371] Buffer I/O error on device mmcblk0p2, logical block 181632
[   60.533371] lost page write due to I/O error on mmcblk0p2

Presumably this is an off-by-one error in the hardware.  Incrementing
the timeout count value that we stuff into the TIMEOUT_CONTROL register
gets us a value that works.  This bug was originally discovered by
Pierre Ossman, I believe.

[thanks to Robert Millan for proving that this was still a problem]

Signed-off-by: Andres Salomon <dilinger@...ian.org>
---
 drivers/mmc/host/sdhci.c |   12 +++++++++++-
 1 files changed, 11 insertions(+), 1 deletions(-)

diff --git a/drivers/mmc/host/sdhci.c b/drivers/mmc/host/sdhci.c
index 5b74c8c..2b3f06a 100644
--- a/drivers/mmc/host/sdhci.c
+++ b/drivers/mmc/host/sdhci.c
@@ -57,6 +57,8 @@ static unsigned int debug_quirks = 0;
 #define SDHCI_QUIRK_RESET_AFTER_REQUEST			(1<<8)
 /* Controller needs voltage and power writes to happen separately */
 #define SDHCI_QUIRK_NO_SIMULT_VDD_AND_POWER		(1<<9)
+/* Controller has an off-by-one issue with timeout value */
+#define SDHCI_QUIRK_INCR_TIMEOUT_CONTROL		(1<<10)
 
 static const struct pci_device_id pci_ids[] __devinitdata = {
 	{
@@ -134,7 +136,8 @@ static const struct pci_device_id pci_ids[] __devinitdata = {
 		.device         = PCI_DEVICE_ID_MARVELL_CAFE_SD,
 		.subvendor      = PCI_ANY_ID,
 		.subdevice      = PCI_ANY_ID,
-		.driver_data    = SDHCI_QUIRK_NO_SIMULT_VDD_AND_POWER,
+		.driver_data    = SDHCI_QUIRK_NO_SIMULT_VDD_AND_POWER |
+				  SDHCI_QUIRK_INCR_TIMEOUT_CONTROL,
 	},
 
 	{
@@ -479,6 +482,13 @@ static void sdhci_prepare_data(struct sdhci_host *host, struct mmc_data *data)
 			break;
 	}
 
+	/*
+	 * Compensate for an off-by-one error in the CaFe hardware; otherwise,
+	 * a too-small count gives us interrupt timeouts.
+	 */
+	if ((host->chip->quirks & SDHCI_QUIRK_INCR_TIMEOUT_CONTROL))
+		count++;
+
 	if (count >= 0xF) {
 		printk(KERN_WARNING "%s: Too large timeout requested!\n",
 			mmc_hostname(host->mmc));
-- 
1.5.5.3

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