| Message ID | 20250211214645.469279-1-erick.shepherd@ni.com |
|---|---|
| State | New |
| Headers | show |
| Series | mmc: sdhci: Disable SD card clock before changing parameters | expand |
On 11/02/25 23:46, Erick Shepherd wrote: > 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. > > 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> > --- > 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 f4a7733a8ad2..5f91b44891f9 100644 > --- a/drivers/mmc/host/sdhci.c > +++ b/drivers/mmc/host/sdhci.c > @@ -2065,10 +2065,15 @@ 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);
On Tue, 11 Feb 2025 at 22:47, Erick Shepherd <erick.shepherd@ni.com> wrote: > > 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. > > 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> Applied for next, thanks! Kind regards Uffe > --- > 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 f4a7733a8ad2..5f91b44891f9 100644 > --- a/drivers/mmc/host/sdhci.c > +++ b/drivers/mmc/host/sdhci.c > @@ -2065,10 +2065,15 @@ 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); > -- > 2.43.0 >
diff --git a/drivers/mmc/host/sdhci.c b/drivers/mmc/host/sdhci.c index f4a7733a8ad2..5f91b44891f9 100644 --- a/drivers/mmc/host/sdhci.c +++ b/drivers/mmc/host/sdhci.c @@ -2065,10 +2065,15 @@ 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);