On Thu, Apr 28, 2016 at 11:32:50AM +0300, Adrian Hunter wrote: > On 21/04/16 16:54, 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 <ludovic.desroches@xxxxxxxxx> > > --- > > drivers/mmc/host/sdhci-of-at91.c | 24 ++++++++++++++++++++++++ > > 1 file changed, 24 insertions(+) > > > > diff --git a/drivers/mmc/host/sdhci-of-at91.c b/drivers/mmc/host/sdhci-of-at91.c > > index c1923c0..76308b1 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> > > @@ -163,6 +164,7 @@ 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, preset_common = 0x400; /* drv type B, programmable clock mode */ > > preset_common is a constant, so why not #define it? No reason, a mistake, I'll fix it. > > > > > match = of_match_device(sdhci_at91_dt_match, &pdev->dev); > > if (!match) > > @@ -230,6 +232,28 @@ 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(preset_common | preset_div, > > + host->ioaddr + SDHCI_PRESET_FOR_SDR12); > > + preset_div = DIV_ROUND_UP(real_gck_rate, 50000000) - 1; > > + writew(preset_common | preset_div, > > + host->ioaddr + SDHCI_PRESET_FOR_SDR25); > > + preset_div = DIV_ROUND_UP(real_gck_rate, 100000000) - 1; > > + writew(preset_common | preset_div, > > + host->ioaddr + SDHCI_PRESET_FOR_SDR50); > > + preset_div = DIV_ROUND_UP(real_gck_rate, 120000000) - 1; > > + writew(preset_common | preset_div, > > + host->ioaddr + SDHCI_PRESET_FOR_SDR104); > > + preset_div = DIV_ROUND_UP(real_gck_rate, 50000000) - 1; > > + writew(preset_common | preset_div, > > + host->ioaddr + SDHCI_PRESET_FOR_DDR50); > > + > > clk_prepare_enable(priv->mainck); > > clk_prepare_enable(priv->gck); > > > > > -- To unsubscribe from this list: send the line "unsubscribe linux-mmc" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
