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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 /drivers/mmc/host/sdhci-esdhc-imx.c
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>
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