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authorDaniel Drake <dsd@laptop.org>2012-11-25 13:01:19 -0500
committerChris Ball <cjb@laptop.org>2012-12-06 13:55:04 -0500
commit6a66180a252f5856fc25de69c6313831f343f50f (patch)
treee25b03a4cde9e28b229c6ff5418aa93b6ed08d11
parentb0afd8f68adf6a9b671b0420ab9116a36409ef7f (diff)
downloadvexpress-lsk-6a66180a252f5856fc25de69c6313831f343f50f.tar.gz
mmc: sdhci: add quirk for lack of 1.8v support
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. Signed-off-by: Daniel Drake <dsd@laptop.org> Reviewed-by: Philip Rakity <prakity@nvidia.com> Signed-off-by: Chris Ball <cjb@laptop.org>
-rw-r--r--drivers/mmc/host/sdhci.c4
-rw-r--r--include/linux/mmc/sdhci.h2
2 files changed, 6 insertions, 0 deletions
diff --git a/drivers/mmc/host/sdhci.c b/drivers/mmc/host/sdhci.c
index ec3e984129d..f78c5b1329e 100644
--- a/drivers/mmc/host/sdhci.c
+++ b/drivers/mmc/host/sdhci.c
@@ -2867,6 +2867,10 @@ int sdhci_add_host(struct sdhci_host *host)
SDHCI_SUPPORT_DDR50);
}
+ if (host->quirks2 & SDHCI_QUIRK2_NO_1_8_V)
+ caps[1] &= ~(SDHCI_SUPPORT_SDR104 | SDHCI_SUPPORT_SDR50 |
+ SDHCI_SUPPORT_DDR50);
+
/* Any UHS-I mode in caps implies SDR12 and SDR25 support. */
if (caps[1] & (SDHCI_SUPPORT_SDR104 | SDHCI_SUPPORT_SDR50 |
SDHCI_SUPPORT_DDR50))
diff --git a/include/linux/mmc/sdhci.h b/include/linux/mmc/sdhci.h
index b34f3eb95f6..4bbc3301fbb 100644
--- a/include/linux/mmc/sdhci.h
+++ b/include/linux/mmc/sdhci.h
@@ -92,6 +92,8 @@ struct sdhci_host {
#define SDHCI_QUIRK2_HOST_OFF_CARD_ON (1<<0)
#define SDHCI_QUIRK2_HOST_NO_CMD23 (1<<1)
+/* The system physically doesn't support 1.8v, even if the host does */
+#define SDHCI_QUIRK2_NO_1_8_V (1<<2)
int irq; /* Device IRQ */
void __iomem *ioaddr; /* Mapped address */