On 28/04/16 15:59, Ludovic Desroches wrote: > The controller claims to support SDR104. In fact, it only supports a > degraded SDR104 since the maximum frequency of the SD clock is 120 MHz > instead of 208 MHz. > The sdhci core is unaware of it and will compute a wrong clock divider. > We can deal with this specific case by using presets. > > Signed-off-by: Ludovic Desroches <[email protected]>
Acked-by: Adrian Hunter <[email protected]> > --- > > Changes: > - v2: > - use a define for preset_common since it's a constant > > drivers/mmc/host/sdhci-of-at91.c | 26 ++++++++++++++++++++++++++ > 1 file changed, 26 insertions(+) > > diff --git a/drivers/mmc/host/sdhci-of-at91.c > b/drivers/mmc/host/sdhci-of-at91.c > index c1923c0..25f779e 100644 > --- a/drivers/mmc/host/sdhci-of-at91.c > +++ b/drivers/mmc/host/sdhci-of-at91.c > @@ -18,6 +18,7 @@ > #include <linux/delay.h> > #include <linux/err.h> > #include <linux/io.h> > +#include <linux/kernel.h> > #include <linux/mmc/host.h> > #include <linux/mmc/slot-gpio.h> > #include <linux/module.h> > @@ -32,6 +33,8 @@ > #define SDMMC_CACR_CAPWREN BIT(0) > #define SDMMC_CACR_KEY (0x46 << 8) > > +#define SDHCI_AT91_PRESET_COMMON_CONF 0x400 /* drv type B, > programmable clock mode */ > + > struct sdhci_at91_priv { > struct clk *hclock; > struct clk *gck; > @@ -163,6 +166,7 @@ static int sdhci_at91_probe(struct platform_device *pdev) > unsigned int clk_base, clk_mul; > unsigned int gck_rate, real_gck_rate; > int ret; > + unsigned int preset_div; > > match = of_match_device(sdhci_at91_dt_match, &pdev->dev); > if (!match) > @@ -230,6 +234,28 @@ static int sdhci_at91_probe(struct platform_device *pdev) > clk_mul, real_gck_rate); > } > > + /* > + * We have to set preset values because it depends on the clk_mul > + * value. Moreover, SDR104 is supported in a degraded mode since the > + * maximum sd clock value is 120 MHz instead of 208 MHz. For that > + * reason, we need to use presets to support SDR104. > + */ > + preset_div = DIV_ROUND_UP(real_gck_rate, 24000000) - 1; > + writew(SDHCI_AT91_PRESET_COMMON_CONF | preset_div, > + host->ioaddr + SDHCI_PRESET_FOR_SDR12); > + preset_div = DIV_ROUND_UP(real_gck_rate, 50000000) - 1; > + writew(SDHCI_AT91_PRESET_COMMON_CONF | preset_div, > + host->ioaddr + SDHCI_PRESET_FOR_SDR25); > + preset_div = DIV_ROUND_UP(real_gck_rate, 100000000) - 1; > + writew(SDHCI_AT91_PRESET_COMMON_CONF | preset_div, > + host->ioaddr + SDHCI_PRESET_FOR_SDR50); > + preset_div = DIV_ROUND_UP(real_gck_rate, 120000000) - 1; > + writew(SDHCI_AT91_PRESET_COMMON_CONF | preset_div, > + host->ioaddr + SDHCI_PRESET_FOR_SDR104); > + preset_div = DIV_ROUND_UP(real_gck_rate, 50000000) - 1; > + writew(SDHCI_AT91_PRESET_COMMON_CONF | preset_div, > + host->ioaddr + SDHCI_PRESET_FOR_DDR50); > + > clk_prepare_enable(priv->mainck); > clk_prepare_enable(priv->gck); > >
