0797e5f145
When switching SD and SDIO cards from 3.3V to 1.8V signal levels, the clock should be gated for 5 ms during the step. After enabling the clock, the host should wait for at least 1 ms before checking for failure. Failure by the card to switch is indicated by dat[0:3] being pulled low. The host should check for this condition and power-cycle the card if failure is indicated. Add a retry mechanism for the SDIO case. If the voltage switch fails repeatedly, give up and continue the initialization using the original voltage. This patch places a couple of requirements on the host driver: 1) mmc_set_ios with ios.clock = 0 must gate the clock 2) mmc_power_off must actually cut the power to the card 3) The card_busy host_ops member must be implemented if these requirements are not fulfilled, the 1.8V signal voltage switch will still be attempted but may not be successful. Signed-off-by: Johan Rudholm <johan.rudholm@stericsson.com> Signed-off-by: Kevin Liu <kliu5@marvell.com> Acked-by: Ulf Hansson <ulf.hansson@linaro.org> Tested-by: Wei WANG <wei_wang@realsil.com.cn> Signed-off-by: Chris Ball <cjb@laptop.org> |
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| core | ||
| host | ||
| Kconfig | ||
| Makefile | ||