mmc: sdhci: Disable SD card clock before changing parameters

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[ Upstream commit 5f755ba95a ]

Per the SD Host Controller Simplified Specification v4.20 §3.2.3, change
the SD card clock parameters only after first disabling the external card
clock. Doing this fixes a spurious clock pulse on Baytrail and Apollo Lake
SD controllers which otherwise breaks voltage switching with a specific
Swissbit SD card. This change is limited to Intel host controllers to
avoid an issue reported on ARM64 devices.

Signed-off-by: Kyle Roeschley <kyle.roeschley@ni.com>
Signed-off-by: Brad Mouring <brad.mouring@ni.com>
Signed-off-by: Erick Shepherd <erick.shepherd@ni.com>
Acked-by: Adrian Hunter <adrian.hunter@intel.com>
Link: https://lore.kernel.org/r/20250724185354.815888-1-erick.shepherd@ni.com
Signed-off-by: Ulf Hansson <ulf.hansson@linaro.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>

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Erick Shepherd 2025-07-24 13:53:54 -05:00 • committed by Greg Kroah-Hartman

parent c5b5d71cd9

commit ad67d4d8fd

1 changed files with 13 additions and 2 deletions

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drivers/mmc/host/sdhci-pci-core.c

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