mmc: sdhci: Disable SD card clock before changing parameters#272
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gratian merged 1 commit intoni:nilrt/master/6.12from Apr 16, 2026
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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> (cherry picked from commit 5f755ba)
gratian
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Apr 16, 2026
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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.
Acked-by: Adrian Hunter adrian.hunter@intel.com
Link: https://lore.kernel.org/r/20250724185354.815888-1-erick.shepherd@ni.com
(cherry picked from commit 5f755ba)