Hi Peng, Thanks for making the changes.
On 7/13/2026 7:02 PM, Peng Fan (OSS) wrote:
From: Peng Fan <[email protected]> Commit 906ee6785b1c ("mmc: sd: Handle UHS-I voltage signaling without power cycle") added detection of cards already operating at 1.8V signaling via mmc_sd_card_using_v18(). This correctly handles the warm-reboot scenario in mmc_startup(). However, mmc_deinit() strips ALL UHS capabilities from the card caps and calls sd_select_mode_and_width() to downgrade the card before kernel handoff. For a card that has switched to 1.8V, uhs_en is already true (via OCR_S18R in mmc->ocr), so sd_select_mode_and_width() attempts UHS mode selection -- but no UHS modes remain in the filtered caps. The non-UHS fallbacks (SD_HS, MMC_LEGACY) are 3.3V speed modes which, when selected while signaling at 1.8V, leave the card in an inconsistent state it cannot recover from without a power cycle. Per SD Physical Layer Specification: "Once the card enters 1.8V signaling mode, the card cannot be switched to 3.3V signaling without power cycle. If the card receives CMD0, card returns to Idle state but still works with SDR12 timing." Fix by using a UHS capability mask that preserves UHS_SDR12 when the card is operating at 1.8V. SDR12 is the minimum valid UHS-I mode and is always available at 1.8V signaling per the SD specification, so the card is left in a consistent (1.8V) state at a low, safe speed. Fixes: 906ee6785b1c ("mmc: sd: Handle UHS-I voltage signaling without power cycle") Signed-off-by: Peng Fan <[email protected]>
Signed-off-by: Tanmay Kathpalia<[email protected]>
