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Commit 8ed765aa authored by Daniel Drake's avatar Daniel Drake Committed by Chris Ball
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mmc: dt: add no-1-8-v device tree flag 



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: default avatarDaniel Drake <dsd@laptop.org>
Reviewed-by: default avatarPhilip Rakity <prakity@nvidia.com>
Signed-off-by: default avatarChris Ball <cjb@laptop.org>
parent 6a66180a

Documentation/devicetree/bindings/mmc/mmc.txt

+2 −0
Original line number Diff line number Diff line
@@ -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

drivers/mmc/host/sdhci-pltfm.c

+3 −0
Original line number Diff line number Diff line
@@ -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;