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mmc: dt: add no-1-8-v device tree flag

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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, so attempting to
switch to the 1.8v level will result in a situation that cannot be
recovered from without physically replugging the SD card.

Add a device tree flag that can be used on systems like these,
and hook it up to the equivalent SDHCI quirk.

Signed-off-by: Daniel Drake <dsd@laptop.org>
Reviewed-by: Philip Rakity <prakity@nvidia.com>
Signed-off-by: Chris Ball <cjb@laptop.org>
This commit is contained in:
Daniel Drake 2012-11-25 13:02:54 -05:00 committed by Chris Ball
parent 6a66180a25
commit 8ed765aac3
2 changed files with 5 additions and 0 deletions
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2
Documentation/devicetree/bindings/mmc/mmc.txt
View File

@ -21,6 +21,8 @@ Optional properties:
- cd-inverted: when present, polarity on the cd gpio line is inverted
- wp-inverted: when present, polarity on the wp gpio line is inverted
- max-frequency: maximum operating clock frequency
- no-1-8-v: when present, denotes that 1.8v card voltage is not supported on
this system, even if the controller claims it is.
Optional SDIO properties:
- keep-power-in-suspend: Preserves card power during a suspend/resume cycle

3
drivers/mmc/host/sdhci-pltfm.c
View File

@ -78,6 +78,9 @@ void sdhci_get_of_property(struct platform_device *pdev)
if (of_get_property(np, "broken-cd", NULL))
host->quirks |= SDHCI_QUIRK_BROKEN_CARD_DETECTION;
if (of_get_property(np, "no-1-8-v", NULL))
host->quirks2 |= SDHCI_QUIRK2_NO_1_8_V;
if (of_device_is_compatible(np, "fsl,p2020-rev1-esdhc"))
host->quirks |= SDHCI_QUIRK_BROKEN_DMA;