On Thu, May 07, 2026 at 08:48:36PM -0300, Hiago De Franco wrote:
>CV1800B SDHCI controller does support 1.8V, however, boards like
>MilkV-Duo 256M do not have a VCCIO 1.8V regulator (the bus is wired for
>3.3V only).
>
>These boards set 'no-1-8-v' in their device tree, and mmc_of_parse()
>does respect this property. Later, when sdhci_setup_cfg() is called, it
>reads SDHCI_CAPABILITIES_1 from the hardware and unconditionally adds
>the UHS caps again based on what the controller advertises. Since the
>board cannot switch to 1.8V, the host issues CMD11 (voltage switch
>request), the card transitions, but the bus stays at 3.3V. The SD card
>stops responding until the next power cycle.
>
>Before calling sdhci_setup_cfg(), set the SDHCI_QUIRK_NO_1_8_V quirk
>when 'no-1-8-v' is present. The quirk causes the SDR104/SDR50/DDR50 bits
>to be masked out of the caps, allowing the card to initialize properly.
>
>This matches the pattern used by zynq_sdhci.
>
>Fixes: eb36f28ff721 ("mmc: cv1800b: Add sdhci driver support for cv1800b SoC")
>Signed-off-by: Hiago De Franco <[email protected]>Reviewed-by: Peng Fan <[email protected]>
