mmc: sd.c Set Non Default Drive Strength via platform

Commit Message

Philip Rakity July 6, 2011, 12:01 a.m. UTC

Non default Drive Strength cannot be set automatically.
It is a function of the board design and only if there
is a specific platform handler can it to set.  The platform
handler needs to take into account the board design.  Pass
to the platform code the necessary information.

For example:  The card and host controller may indicate
they support HIGH and LOW drive strength.  There is no way
to know what should be chosen without specific board knowledge.
There is not mechanism (like ethernet duplex or speed pulses)
to determine what should be done.

If no platform handler is defined -- use the default value.

Signed-off-by: Philip Rakity <[e-mail]>
---
 drivers/mmc/core/sd.c |   68 ++++++++++++++++++++++++++++---------------------
 1 files changed, 39 insertions(+), 29 deletions(-)

Patch

diff --git a/drivers/mmc/core/sd.c b/drivers/mmc/core/sd.c
index ff27741..633975f 100644
--- a/drivers/mmc/core/sd.c
+++ b/drivers/mmc/core/sd.c
@@ -409,52 +409,62 @@  out:
 
 static int sd_select_driver_type(struct mmc_card *card, u8 *status)
 {
-	int host_drv_type = 0, card_drv_type = 0;
+	int host_drv_type = SD_DRIVER_TYPE_B;
+	int card_drv_type = SD_DRIVER_TYPE_B;
+	int drive_strength;
 	int err;
 
 	/*
 	 * 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->ops->select_drive_strength)
+		return 0;
+
+	if (card->host->caps & MMC_CAP_DRIVER_TYPE_A)
+		host_drv_type |= SD_DRIVER_TYPE_A;
+
+	if (card->host->caps & MMC_CAP_DRIVER_TYPE_C)
+		host_drv_type |= SD_DRIVER_TYPE_C;
+
+	if (card->host->caps & MMC_CAP_DRIVER_TYPE_D)
+		host_drv_type |= SD_DRIVER_TYPE_D;
+
+	if (card->sw_caps.sd3_drv_type & SD_DRIVER_TYPE_A)
+		card_drv_type |= SD_DRIVER_TYPE_A;
+
+	if (card->sw_caps.sd3_drv_type & SD_DRIVER_TYPE_C)
+		card_drv_type |= SD_DRIVER_TYPE_C;
+
+	if (card->sw_caps.sd3_drv_type & SD_DRIVER_TYPE_D)
+		card_drv_type |= SD_DRIVER_TYPE_D;
+
+	/*
+	 * The drive strength that the hardware can support
+	 * depends on the board design.  Pass the appropriate
+	 * information and let the hardware specific code
+	 * return what is possible given the options
+	 */
+	drive_strength = card->host->ops->select_drive_strength(
+		card->sw_caps.uhs_max_dtr,
+		host_drv_type, card_drv_type);
 
-	err = mmc_sd_switch(card, 1, 2, card_drv_type, status);
+	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",
+	if ((status[15] & 0xF) != drive_strength) {
+		printk(KERN_WARNING "%s: Problem setting drive strength!\n",
 			mmc_hostname(card->host));
 		return 0;
 	}
 
-	mmc_set_driver_type(card->host, host_drv_type);
+	mmc_set_driver_type(card->host, drive_strength);
 
 	return 0;
 }