linux-kernel - [PATCH V2] sdhci: always use max timeout for xfers

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Date:	Fri, 25 Feb 2011 10:49:25 -0800
From:	Philip Rakity <prakity@...vell.com>
To:	Wolfram Sang <w.sang@...gutronix.de>
CC:	"linux-mmc@...r.kernel.org" <linux-mmc@...r.kernel.org>,
	Kyungmin Park <kyungmin.park@...sung.com>,
	Jae hoon Chung <jh80.chung@...il.com>,
	Chuanxiao Dong <chuanxiao.dong@...el.com>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>
Subject: [PATCH V2] sdhci: always use max timeout for xfers

v2

use define for max timeout.  remove subroutine call and just
set the register directly

v1

The card/host controller may sometimes return a value that is
too low and cause the h/w to timeout a transfer that would have
worked.  Using the maximum value avoids this.

Signed-off-by: Philip Rakity <prakity@...vell.com>
---
 drivers/mmc/host/sdhci.c |   59 +++++----------------------------------------
 drivers/mmc/host/sdhci.h |    1 +
 2 files changed, 8 insertions(+), 52 deletions(-)

diff --git a/drivers/mmc/host/sdhci.c b/drivers/mmc/host/sdhci.c
index 655617c..d615173 100644
--- a/drivers/mmc/host/sdhci.c
+++ b/drivers/mmc/host/sdhci.c
@@ -592,55 +592,6 @@ static void sdhci_adma_table_post(struct sdhci_host *host,
 		data->sg_len, direction);
 }
 
-static u8 sdhci_calc_timeout(struct sdhci_host *host, struct mmc_data *data)
-{
-	u8 count;
-	unsigned target_timeout, current_timeout;
-
-	/*
-	 * If the host controller provides us with an incorrect timeout
-	 * value, just skip the check and use 0xE.  The hardware may take
-	 * longer to time out, but that's much better than having a too-short
-	 * timeout value.
-	 */
-	if (host->quirks & SDHCI_QUIRK_BROKEN_TIMEOUT_VAL)
-		return 0xE;
-
-	/* timeout in us */
-	target_timeout = data->timeout_ns / 1000 +
-		data->timeout_clks / host->clock;
-
-	if (host->quirks & SDHCI_QUIRK_DATA_TIMEOUT_USES_SDCLK)
-		host->timeout_clk = host->clock / 1000;
-
-	/*
-	 * Figure out needed cycles.
-	 * We do this in steps in order to fit inside a 32 bit int.
-	 * The first step is the minimum timeout, which will have a
-	 * minimum resolution of 6 bits:
-	 * (1) 2^13*1000 > 2^22,
-	 * (2) host->timeout_clk < 2^16
-	 *     =>
-	 *     (1) / (2) > 2^6
-	 */
-	count = 0;
-	current_timeout = (1 << 13) * 1000 / host->timeout_clk;
-	while (current_timeout < target_timeout) {
-		count++;
-		current_timeout <<= 1;
-		if (count >= 0xF)
-			break;
-	}
-
-	if (count >= 0xF) {
-		printk(KERN_WARNING "%s: Too large timeout requested!\n",
-			mmc_hostname(host->mmc));
-		count = 0xE;
-	}
-
-	return count;
-}
-
 static void sdhci_set_transfer_irqs(struct sdhci_host *host)
 {
 	u32 pio_irqs = SDHCI_INT_DATA_AVAIL | SDHCI_INT_SPACE_AVAIL;
@@ -654,7 +605,6 @@ static void sdhci_set_transfer_irqs(struct sdhci_host *host)
 
 static void sdhci_prepare_data(struct sdhci_host *host, struct mmc_data *data)
 {
-	u8 count;
 	u8 ctrl;
 	int ret;
 
@@ -671,8 +621,13 @@ static void sdhci_prepare_data(struct sdhci_host *host, struct mmc_data *data)
 	host->data = data;
 	host->data_early = 0;
 
-	count = sdhci_calc_timeout(host, data);
-	sdhci_writeb(host, count, SDHCI_TIMEOUT_CONTROL);
+	/*
+	 * The host controller/card can provide us with an incorrect timeout
+	 * value, just use the maximum value 0xE.  The hardware may take
+	 * longer to time out, but that's much better than having a too-short
+	 * timeout value.
+	 */
+	sdhci_writeb(host, SDHCI_TIMEOUT_MAX, SDHCI_TIMEOUT_CONTROL);
 
 	if (host->flags & (SDHCI_USE_SDMA | SDHCI_USE_ADMA))
 		host->flags |= SDHCI_REQ_USE_DMA;
diff --git a/drivers/mmc/host/sdhci.h b/drivers/mmc/host/sdhci.h
index 1f032c0..19b4d41 100644
--- a/drivers/mmc/host/sdhci.h
+++ b/drivers/mmc/host/sdhci.h
@@ -103,6 +103,7 @@
 #define  SDHCI_CLOCK_INT_EN	0x0001
 
 #define SDHCI_TIMEOUT_CONTROL	0x2E
+#define  SDHCI_TIMEOUT_MAX	0xE
 
 #define SDHCI_SOFTWARE_RESET	0x2F
 #define  SDHCI_RESET_ALL	0x01
-- 
1.7.0.4

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