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From: Philip Rakity <prakity@marvell.com>
To: "linux-mmc@vger.kernel.org" <linux-mmc@vger.kernel.org>
Cc: Arindam Nath <arindam.nath@amd.com>
Subject: [RFC] mmc: Non Default UHS Drive Strength must use board specific code
Date: Tue, 17 May 2011 13:58:40 -0700	[thread overview]
Message-ID: <D2C557E7-F39F-4EC5-84F8-F851AA00CE6C@marvell.com> (raw)


Note:  This is being send out for comment.  We are still in the process of testing this change
but we would like to have community review at this time.


SD 3.0 introduced additional drive strengths for UHS.
The card and the host can indicate 4 drive strengths as a bit
mask.  Without local design knowledge of the board it is not
possible to select the correct drive strength.  Unfortunately
there is not the equivalent of ethernet auto-negotiate in the
SD 3.0 Physical Spec at this time.

We punt the problem by asking any platform specific code to
handle the drive strength problem.  If non is defined we default
the drive strength to the manadory TYPE_B value.

Signed-off-by: Philip Rakity <prakity@marvell.com>
---
 drivers/mmc/core/core.c  |   15 ++++++++++
 drivers/mmc/core/core.h  |    5 +++
 drivers/mmc/core/sd.c    |   65 ++++++++++++++++++++++++----------------------
 drivers/mmc/host/sdhci.c |   16 +++++++++++
 drivers/mmc/host/sdhci.h |    5 +++
 include/linux/mmc/host.h |   13 ++++++---
 6 files changed, 84 insertions(+), 35 deletions(-)

diff --git a/drivers/mmc/core/core.c b/drivers/mmc/core/core.c
index 68091dd..49df27b 100644
--- a/drivers/mmc/core/core.c
+++ b/drivers/mmc/core/core.c
@@ -964,6 +964,21 @@ int mmc_set_signal_voltage(struct mmc_host *host, int signal_voltage, bool cmd11
 	return err;
 }
 
+unsigned int mmc_select_drive_strength(struct mmc_host *host,
+			unsigned int bus_mode,
+			unsigned int max_dtr,
+			unsigned int host_drv_type,
+			unsigned int card_drv_type)
+{
+	if (host->ops->select_drive_strength)
+		return host->ops->select_drive_strength(host,
+			bus_mode, max_dtr,
+			host_drv_type, card_drv_type);
+
+	/* return default strength if no handler in driver */
+	return MMC_SET_DRIVER_TYPE_B;
+}
+
 /*
  * Select timing parameters for host.
  */
diff --git a/drivers/mmc/core/core.h b/drivers/mmc/core/core.h
index d9411ed..8bc289c 100644
--- a/drivers/mmc/core/core.h
+++ b/drivers/mmc/core/core.h
@@ -43,6 +43,11 @@ int mmc_set_signal_voltage(struct mmc_host *host, int signal_voltage,
 			   bool cmd11);
 void mmc_set_timing(struct mmc_host *host, unsigned int timing);
 void mmc_set_driver_type(struct mmc_host *host, unsigned int drv_type);
+unsigned int mmc_select_drive_strength(struct mmc_host *host,
+			unsigned int bus_mode,
+			unsigned int max_dtr,
+			unsigned int host_drv_type,
+			unsigned int card_drv_type);
 
 static inline void mmc_delay(unsigned int ms)
 {
diff --git a/drivers/mmc/core/sd.c b/drivers/mmc/core/sd.c
index 596d0b9..a268ead 100644
--- a/drivers/mmc/core/sd.c
+++ b/drivers/mmc/core/sd.c
@@ -405,54 +405,57 @@ out:
 	return err;
 }
 
+
 static int sd_select_driver_type(struct mmc_card *card, u8 *status)
 {
-	int host_drv_type = 0, card_drv_type = 0;
+	unsigned int host_drv_type = MMC_SET_DRIVER_TYPE_B;
+	unsigned int card_drv_type = MMC_SET_DRIVER_TYPE_B;
 	int err;
+	unsigned char drive_strength;
 
 	/*
 	 * If the host doesn't support any of the Driver Types A,C or D,
-	 * default Driver Type B is used.
+	 * or there is no board specific handler then default Driver
+	 * Type B is used.
 	 */
 	if (!(card->host->caps & (MMC_CAP_DRIVER_TYPE_A | MMC_CAP_DRIVER_TYPE_C
 	    | MMC_CAP_DRIVER_TYPE_D)))
 		return 0;
 
-	if (card->host->caps & MMC_CAP_DRIVER_TYPE_A) {
-		host_drv_type = MMC_SET_DRIVER_TYPE_A;
-		if (card->sw_caps.sd3_drv_type & SD_DRIVER_TYPE_A)
-			card_drv_type = MMC_SET_DRIVER_TYPE_A;
-		else if (card->sw_caps.sd3_drv_type & SD_DRIVER_TYPE_B)
-			card_drv_type = MMC_SET_DRIVER_TYPE_B;
-		else if (card->sw_caps.sd3_drv_type & SD_DRIVER_TYPE_C)
-			card_drv_type = MMC_SET_DRIVER_TYPE_C;
-	} else if (card->host->caps & MMC_CAP_DRIVER_TYPE_C) {
-		host_drv_type = MMC_SET_DRIVER_TYPE_C;
-		if (card->sw_caps.sd3_drv_type & SD_DRIVER_TYPE_C)
-			card_drv_type = MMC_SET_DRIVER_TYPE_C;
-	} else if (!(card->host->caps & MMC_CAP_DRIVER_TYPE_D)) {
-		/*
-		 * If we are here, that means only the default driver type
-		 * B is supported by the host.
-		 */
-		host_drv_type = MMC_SET_DRIVER_TYPE_B;
-		if (card->sw_caps.sd3_drv_type & SD_DRIVER_TYPE_B)
-			card_drv_type = MMC_SET_DRIVER_TYPE_B;
-		else if (card->sw_caps.sd3_drv_type & SD_DRIVER_TYPE_C)
-			card_drv_type = MMC_SET_DRIVER_TYPE_C;
-	}
+	if (card->host->caps & MMC_CAP_DRIVER_TYPE_A)
+		host_drv_type |= MMC_SET_DRIVER_TYPE_A;
+
+	if (card->host->caps & MMC_CAP_DRIVER_TYPE_C)
+		host_drv_type |= MMC_SET_DRIVER_TYPE_C;
+
+	if (card->host->caps & MMC_CAP_DRIVER_TYPE_D)
+		host_drv_type |= MMC_SET_DRIVER_TYPE_D;
 
-	err = mmc_sd_switch(card, 1, 2, card_drv_type, status);
+	if (card->sw_caps.sd3_drv_type & SD_DRIVER_TYPE_A)
+		card_drv_type |= MMC_SET_DRIVER_TYPE_A;
+
+	if (card->sw_caps.sd3_drv_type & SD_DRIVER_TYPE_C)
+		card_drv_type |= MMC_SET_DRIVER_TYPE_C;
+
+	if (card->sw_caps.sd3_drv_type & SD_DRIVER_TYPE_D)
+		card_drv_type |= MMC_SET_DRIVER_TYPE_D;
+
+	drive_strength = mmc_select_drive_strength(card->host,
+		card->sw_caps.sd3_bus_mode,
+		card->sw_caps.uhs_max_dtr,
+		host_drv_type, card_drv_type);
+
+	err = mmc_sd_switch(card, 1, 2, drive_strength, status);
 	if (err)
 		return err;
 
-	if ((status[15] & 0xF) != card_drv_type) {
-		printk(KERN_WARNING "%s: Problem setting driver strength!\n",
-			mmc_hostname(card->host));
+	if ((status[15] & 0xF) != drive_strength) {
+		printk(KERN_WARNING "%s: Problem setting driver strength %d\n",
+			mmc_hostname(card->host), drive_strength);
 		return 0;
 	}
 
-	mmc_set_driver_type(card->host, host_drv_type);
+	mmc_set_driver_type(card->host, drive_strength);
 
 	return 0;
 }
@@ -488,7 +491,7 @@ static int sd_set_bus_speed_mode(struct mmc_card *card, u8 *status)
 			card->sw_caps.uhs_max_dtr = UHS_SDR50_MAX_DTR;
 	} else if ((card->host->caps & (MMC_CAP_UHS_SDR104 |
 		    MMC_CAP_UHS_SDR50 | MMC_CAP_UHS_SDR25)) &&
-		   (card->sw_caps.sd3_bus_mode & SD_MODE_UHS_SDR25)) {
+		   (card->sw_caps.uhs_max_dtr & SD_MODE_UHS_SDR25)) {
 			bus_speed = UHS_SDR25_BUS_SPEED;
 			timing = MMC_TIMING_UHS_SDR25;
 			card->sw_caps.uhs_max_dtr = UHS_SDR25_MAX_DTR;
diff --git a/drivers/mmc/host/sdhci.c b/drivers/mmc/host/sdhci.c
index cc63f5e..ebeb986 100644
--- a/drivers/mmc/host/sdhci.c
+++ b/drivers/mmc/host/sdhci.c
@@ -1766,6 +1766,21 @@ static void sdhci_enable_preset_value(struct mmc_host *mmc, bool enable)
 	spin_unlock_irqrestore(&host->lock, flags);
 }
 
+static unsigned int sdhci_select_drive_strength(struct mmc_host *host,
+			unsigned int bus_mode,
+			unsigned int max_dtr,
+			unsigned int host_drv_type,
+			unsigned int card_drv_type)
+{
+	if (host->ops->select_drive_strength)
+		return host->ops->select_drive_strength(host,
+			bus_mode, max_dtr,
+			host_drv_type, card_drv_type);
+
+	/* return default strength if no handler in driver */
+	return MMC_SET_DRIVER_TYPE_B;
+}
+
 static const struct mmc_host_ops sdhci_ops = {
 	.request	= sdhci_request,
 	.set_ios	= sdhci_set_ios,
@@ -1774,6 +1789,7 @@ static const struct mmc_host_ops sdhci_ops = {
 	.start_signal_voltage_switch	= sdhci_start_signal_voltage_switch,
 	.execute_tuning			= sdhci_execute_tuning,
 	.enable_preset_value		= sdhci_enable_preset_value,
+	.select_drive_strength		= sdhci_select_drive_strength,
 };
 
 /*****************************************************************************\
diff --git a/drivers/mmc/host/sdhci.h b/drivers/mmc/host/sdhci.h
index 7e28eec..8f48aca 100644
--- a/drivers/mmc/host/sdhci.h
+++ b/drivers/mmc/host/sdhci.h
@@ -271,6 +271,11 @@ struct sdhci_ops {
 	void	(*platform_reset_enter)(struct sdhci_host *host, u8 mask);
 	void	(*platform_reset_exit)(struct sdhci_host *host, u8 mask);
 	int	(*set_uhs_signaling)(struct sdhci_host *host, unsigned int uhs);
+	unsigned int	(*select_drive_strength)(struct sdhci_host *host,
+			unsigned int bus_mode,
+			unsigned int max_dtr,
+			unsigned int host_drv_type,
+			unsigned int card_drv_type);
 
 };
 
diff --git a/include/linux/mmc/host.h b/include/linux/mmc/host.h
index de32e6a..6c2aeab 100644
--- a/include/linux/mmc/host.h
+++ b/include/linux/mmc/host.h
@@ -70,10 +70,10 @@ struct mmc_ios {
 
 	unsigned char	drv_type;		/* driver type (A, B, C, D) */
 
-#define MMC_SET_DRIVER_TYPE_B	0
-#define MMC_SET_DRIVER_TYPE_A	1
-#define MMC_SET_DRIVER_TYPE_C	2
-#define MMC_SET_DRIVER_TYPE_D	3
+#define MMC_SET_DRIVER_TYPE_B	(1<<0)
+#define MMC_SET_DRIVER_TYPE_A	(1<<1)
+#define MMC_SET_DRIVER_TYPE_C	(1<<2)
+#define MMC_SET_DRIVER_TYPE_D	(1<<3)
 };
 
 struct mmc_host_ops {
@@ -139,6 +139,11 @@ struct mmc_host_ops {
 	int	(*start_signal_voltage_switch)(struct mmc_host *host, struct mmc_ios *ios);
 	int	(*execute_tuning)(struct mmc_host *host);
 	void	(*enable_preset_value)(struct mmc_host *host, bool enable);
+	unsigned int	(*select_drive_strength)(struct mmc_host *host,
+			unsigned int bus_mode,
+			unsigned int max_dtr,
+			unsigned int host_drv_type,
+			unsigned int card_drv_type);
 };
 
 struct mmc_card;
-- 
1.7.0.4



             reply	other threads:[~2011-05-17 20:59 UTC|newest]

Thread overview: 4+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2011-05-17 20:58 Philip Rakity [this message]
2011-05-18  5:49 ` [RFC] mmc: Non Default UHS Drive Strength must use board specific code Nath, Arindam
2011-05-18 15:04   ` Philip Rakity
2011-05-18 18:36   ` [RFC v2] " Philip Rakity

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