From: Erick Shepherd erick.shepherd@ni.com
[ Upstream commit fb3bbc46c94f261b6156ee863c1b06c84cf157dc ]
Per the SD Host Controller Simplified Specification v4.20 ยง3.2.3, 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.
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/20250211214645.469279-1-erick.shepherd@ni.com Signed-off-by: Ulf Hansson ulf.hansson@linaro.org Signed-off-by: Sasha Levin sashal@kernel.org --- drivers/mmc/host/sdhci.c | 9 +++++++-- 1 file changed, 7 insertions(+), 2 deletions(-)
diff --git a/drivers/mmc/host/sdhci.c b/drivers/mmc/host/sdhci.c index 4b91c9e966357..8ae76300d157d 100644 --- a/drivers/mmc/host/sdhci.c +++ b/drivers/mmc/host/sdhci.c @@ -2035,10 +2035,15 @@ void sdhci_set_clock(struct sdhci_host *host, unsigned int clock)
host->mmc->actual_clock = 0;
- sdhci_writew(host, 0, SDHCI_CLOCK_CONTROL); + clk = sdhci_readw(host, SDHCI_CLOCK_CONTROL); + if (clk & SDHCI_CLOCK_CARD_EN) + sdhci_writew(host, clk & ~SDHCI_CLOCK_CARD_EN, + SDHCI_CLOCK_CONTROL);
- if (clock == 0) + if (clock == 0) { + sdhci_writew(host, 0, SDHCI_CLOCK_CONTROL); return; + }
clk = sdhci_calc_clk(host, clock, &host->mmc->actual_clock); sdhci_enable_clk(host, clk);