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authorPhilip Rakity <prakity@marvell.com>2011-07-06 08:51:32 -0700
committerChris Ball <cjb@laptop.org>2011-07-20 17:21:16 -0400
commitca8e99b32e3863c98ac958617cc157a00bf445b8 (patch)
tree2e8b5d9fc5577ef2c795c9cd4ca40ae21e508699 /drivers/mmc/core
parentee8a43a51c7681f19fe23b6b936e1d8094a8b7d1 (diff)
mmc: core: Set non-default Drive Strength via platform hook
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 be 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. Setting HIGH may lead to reflections and setting LOW may not suffice. There is no mechanism (like ethernet duplex or speed pulses) to determine what should be done automatically. If no platform handler is defined -- use the default value. Signed-off-by: Philip Rakity <prakity@marvell.com> Reviewed-by: Arindam Nath <arindam.nath@amd.com> Signed-off-by: Chris Ball <cjb@laptop.org>
Diffstat (limited to 'drivers/mmc/core')
-rw-r--r--drivers/mmc/core/sd.c68
1 files changed, 39 insertions, 29 deletions
diff --git a/drivers/mmc/core/sd.c b/drivers/mmc/core/sd.c
index ff2774128aa..633975ff2bb 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;
}