mmc: sdhci: add quirk for lack of 1.8v support
Jeetesh Burman [Mon, 16 Dec 2013 12:17:43 +0000 (17:17 +0530)]
The OLPC XO-1.75 laptop includes a SDHCI controller which is 1.8v
capable, and it truthfully reports so in its capabilities. This
alternate voltage is used for driving new "UHS-I" SD cards at their
full speed.

However, what the controller doesn't know is that the motherboard
physically doesn't have a 1.8v supply available.

Add a quirk so that systems such as this one can override disable
1.8v support, adding support for UHS-I cards (by running them at
3.3v).

This avoids a problem where the system would first try to run the
card at 1.8v, fail, and then not be able to fully reset the card
to retry at the normal 3.3v voltage.

This is more appropriate than using the MISSING_CAPS quirk, which
is intended for cases where the SDHCI controller is actually lying
about its capabilities, and would force us to somehow override both
caps words from another source.

Bug 1402031

Change-Id: I7ca070a13241e6403eb2e243ebbc441a311110bc
Signed-off-by: Daniel Drake <dsd@laptop.org>
Reviewed-by: Philip Rakity <prakity@nvidia.com>
Signed-off-by: Chris Ball <cjb@laptop.org>
Signed-off-by: Jeetesh Burman <jburman@nvidia.com>
Reviewed-on: http://git-master/r/346323
Reviewed-by: Matthew Pedro <mapedro@nvidia.com>
Tested-by: Matthew Pedro <mapedro@nvidia.com>

drivers/mmc/host/sdhci.c
include/linux/mmc/sdhci.h

index 3a440dc..a1c7484 100644 (file)
@@ -2658,9 +2658,13 @@ int sdhci_add_host(struct sdhci_host *host)
            mmc_card_is_removable(mmc) && !(host->ops->get_cd))
                mmc->caps |= MMC_CAP_NEEDS_POLL;
 
-       /* UHS-I mode(s) supported by the host controller. */
-       if (host->version >= SDHCI_SPEC_300)
-               mmc->caps |= MMC_CAP_UHS_SDR12 | MMC_CAP_UHS_SDR25;
+       if (host->quirks & SDHCI_QUIRK2_NO_1_8_V)
+               caps[1] &= ~(SDHCI_SUPPORT_SDR104 | SDHCI_SUPPORT_SDR50 |
+                            SDHCI_SUPPORT_DDR50);
+       else
+               /* UHS-I mode(s) supported by the host controller. */
+               if (host->version >= SDHCI_SPEC_300)
+                       mmc->caps |= MMC_CAP_UHS_SDR12 | MMC_CAP_UHS_SDR25;
 
        /* SDR104 supports also implies SDR50 support */
        if (caps[1] & SDHCI_SUPPORT_SDR104)
index 5ee4839..db86304 100644 (file)
@@ -93,6 +93,8 @@ struct sdhci_host {
 #define SDHCI_QUIRK_NON_STANDARD_TUNING                (1ULL<<33)
 /* Controller doesn't calculate max_discard_to */
 #define SDHCI_QUIRK_NO_CALC_MAX_DISCARD_TO             (1ULL<<34)
+/* The system physically doesn't support 1.8v, even if the host does */
+#define SDHCI_QUIRK2_NO_1_8_V                          (1ULL<<35)
 
        int irq;                /* Device IRQ */
        void __iomem *ioaddr;   /* Mapped address */