--- linux-2.6.38/drivers/mmc/host/sdhci.c	2011-05-28 18:52:02.799702610 -0400
+++ linux-2.6.38/drivers/mmc/host/sdhci.c	2011-05-28 18:46:55.356409956 -0400
@@ -602,15 +602,19 @@
 	 * longer to time out, but that's much better than having a too-short
 	 * timeout value.
 	 */
+#ifndef CONFIG_SDHCI_STUDY_TIMEOUTS
 	if (host->quirks & SDHCI_QUIRK_BROKEN_TIMEOUT_VAL)
 		return 0xE;
+#endif
 
 	/* timeout in us */
 	target_timeout = data->timeout_ns / 1000 +
 		(data->timeout_clks * 1000) / (host->clock / 1000);
 
+#ifndef CONFIG_SDHCI_STUDY_TIMEOUTS
 	if (host->quirks & SDHCI_QUIRK_DATA_TIMEOUT_USES_SDCLK)
 		host->timeout_clk = host->clock / 1000;
+#endif
 
 	/*
 	 * Figure out needed cycles.
@@ -671,6 +675,14 @@
 	host->data_early = 0;
 
 	count = sdhci_calc_timeout(host, data);
+#ifdef CONFIG_SDHCI_STUDY_TIMEOUTS
+	{
+		struct timespec now = CURRENT_TIME;
+		host->start_time = timespec_to_ns(&now);
+		host->expected_timeout = (u64)(1 << (13+count)) * 1000000 / host->timeout_clk;
+		host->timeout_counter = count;
+	}
+#endif
 	sdhci_writeb(host, count, SDHCI_TIMEOUT_CONTROL);
 
 	if (host->flags & (SDHCI_USE_SDMA | SDHCI_USE_ADMA))
@@ -1522,7 +1534,17 @@
 
 	if ((intmask & SDHCI_INT_DATA_TIMEOUT) &&
 	    !(intmask & SDHCI_INT_DATA_END))
+	{
+#ifdef CONFIG_SDHCI_STUDY_TIMEOUTS
+		struct timespec now = CURRENT_TIME;
+		u64 actual_timeout = timespec_to_ns(&now) - host->start_time;
+		printk(KERN_WARNING "sdhci: timeout, requested %lldns actual %lldns, TMCLK configured %d estimated %lld\n",
+		       (long long)host->expected_timeout, (long long)actual_timeout,
+		       host->timeout_clk,
+		       (long long)((u64)(1 << (13+host->timeout_counter)) * 1000000 / actual_timeout));
+#endif
 		host->data->error = -ETIMEDOUT;
+	}
 	else if (intmask & SDHCI_INT_DATA_END_BIT)
 		host->data->error = -EILSEQ;
 	else if ((intmask & SDHCI_INT_DATA_CRC) &&
--- linux-2.6.38/include/linux/mmc/sdhci.h	2011-03-14 21:20:32.000000000 -0400
+++ linux-2.6.38/include/linux/mmc/sdhci.h	2011-05-28 18:02:12.632367830 -0400
@@ -17,6 +17,8 @@
 #include <linux/io.h>
 #include <linux/mmc/host.h>
 
+#define CONFIG_SDHCI_STUDY_TIMEOUTS
+
 struct sdhci_host {
 	/* Data set by hardware interface driver */
 	const char *hw_name;	/* Hardware bus name */
@@ -145,6 +147,11 @@
 	unsigned int            ocr_avail_sd;
 	unsigned int            ocr_avail_mmc;
 
+#ifdef CONFIG_SDHCI_STUDY_TIMEOUTS
+	u64 expected_timeout, start_time;
+	u8 timeout_counter;
+#endif
+
 	unsigned long private[0] ____cacheline_aligned;
 };
 #endif /* __SDHCI_H */