Add support for power-off-delay-us DT property to handle slow RC discharge on MMC VDD rails during power cycles. SD spec (section 6.4.1.3) requires VDD below 0.5V for minimum 1ms during power cycle. AM65x EVM requires a delay of 650ms after power-off to reach below 0.5V threshold and allow proper RC discharge.
AM65 EVM power cycle issue was exposed with [0]. An initial implementation was sent [1], but would have created binding mismatch with Linux so binding update was completed first on Linux side [2]. Now that binding is established and device tree updates in progress [3], add U-Boot power-off delay capability. [0] https://lore.kernel.org/u-boot/[email protected]/ [2] https://lore.kernel.org/linux-mmc/[email protected]/ [3] https://lore.kernel.org/linux-devicetree/[email protected]/ Link to v1: [1] https://lore.kernel.org/u-boot/[email protected]/ Changes since v1: - Implement delay in MMC core instead of voltage regulator driver according to binding update [2] Judith Mendez (1): mmc: core: Add power-off-delay-us support for slow RC discharge drivers/mmc/mmc.c | 8 ++++++++ 1 file changed, 8 insertions(+) -- 2.34.1
