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| author | Erick Shepherd <erick.shepherd@ni.com> | 2025-02-11 15:46:45 -0600 |
|---|---|---|
| committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2025-05-29 11:02:21 +0200 |
| commit | 28306c58daf81bdfb01b1f12fa5936a1d5afbefa (patch) | |
| tree | 7244d064c850215ac7d81437dc1faffcbe13da2c /drivers/mmc | |
| parent | 38828e0dc771c730c9289d4a6deb8815ad3867ed (diff) | |
| download | linux-28306c58daf81bdfb01b1f12fa5936a1d5afbefa.tar.gz linux-28306c58daf81bdfb01b1f12fa5936a1d5afbefa.tar.bz2 linux-28306c58daf81bdfb01b1f12fa5936a1d5afbefa.zip | |
mmc: sdhci: Disable SD card clock before changing parameters
[ 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>
Diffstat (limited to 'drivers/mmc')
| -rw-r--r-- | drivers/mmc/host/sdhci.c | 9 |
1 files changed, 7 insertions, 2 deletions
diff --git a/drivers/mmc/host/sdhci.c b/drivers/mmc/host/sdhci.c index 4b91c9e96635..8ae76300d157 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); |