Both f_max and f_min will be informed for core layer to request valid clock rate. But current setting from 'host->bus_hz' may not represent the max/min frequency properly. Even if host can actually support high speed than bus_hz, core layer will not request clock rate over bus_hz. Basically, f_max/f_min can be set with the values according to spec. And then host will make its best effort to meet the rate.
Signed-off-by: Seungwon Jeon <[email protected]> --- .../devicetree/bindings/mmc/synopsis-dw-mshc.txt | 4 ++++ drivers/mmc/host/dw_mmc.c | 14 ++++++++++++-- 2 files changed, 16 insertions(+), 2 deletions(-) diff --git a/Documentation/devicetree/bindings/mmc/synopsis-dw-mshc.txt b/Documentation/devicetree/bindings/mmc/synopsis-dw-mshc.txt index ae5f8e8..fdbf686 100644 --- a/Documentation/devicetree/bindings/mmc/synopsis-dw-mshc.txt +++ b/Documentation/devicetree/bindings/mmc/synopsis-dw-mshc.txt @@ -52,6 +52,9 @@ Optional properties: is specified and the ciu clock is specified then we'll try to set the ciu clock to this at probe time. +* clock-freq-min-max: Minimum and Maximum clock frequency for card output + clock(cclk_out). If it's not specified, max is 200MHZ and min is 400KHz by default. + * num-slots: specifies the number of slots supported by the controller. The number of physical slots actually used could be equal or less than the value specified by num-slots. If this property is not specified, the value @@ -97,6 +100,7 @@ board specific portions as listed below. dwmmc0@12200000 { clock-frequency = <400000000>; + clock-freq-min-max = <400000 200000000>; num-slots = <1>; supports-highspeed; caps2-mmc-hs200-1_8v; diff --git a/drivers/mmc/host/dw_mmc.c b/drivers/mmc/host/dw_mmc.c index a1ce7c0..296d4a4 100644 --- a/drivers/mmc/host/dw_mmc.c +++ b/drivers/mmc/host/dw_mmc.c @@ -50,6 +50,9 @@ #define DW_MCI_RECV_STATUS 2 #define DW_MCI_DMA_THRESHOLD 16 +#define DW_MCI_FREQ_MAX 200000000 +#define DW_MCI_FREQ_MIN 400000 + #ifdef CONFIG_MMC_DW_IDMAC #define IDMAC_INT_CLR (SDMMC_IDMAC_INT_AI | SDMMC_IDMAC_INT_NI | \ SDMMC_IDMAC_INT_CES | SDMMC_IDMAC_INT_DU | \ @@ -1929,6 +1932,7 @@ static int dw_mci_init_slot(struct dw_mci *host, unsigned int id) struct dw_mci_slot *slot; const struct dw_mci_drv_data *drv_data = host->drv_data; int ctrl_id, ret; + u32 freq[2]; u8 bus_width; mmc = mmc_alloc_host(sizeof(struct dw_mci_slot), host->dev); @@ -1944,8 +1948,14 @@ static int dw_mci_init_slot(struct dw_mci *host, unsigned int id) slot->quirks = dw_mci_of_get_slot_quirks(host->dev, slot->id); mmc->ops = &dw_mci_ops; - mmc->f_min = DIV_ROUND_UP(host->bus_hz, 510); - mmc->f_max = host->bus_hz; + if (of_property_read_u32_array(host->dev->of_node, + "clock-freq-min-max", freq, 2)) { + mmc->f_min = DW_MCI_FREQ_MIN; + mmc->f_max = DW_MCI_FREQ_MAX; + } else { + mmc->f_min = freq[0]; + mmc->f_max = freq[1]; + } if (host->pdata->get_ocr) mmc->ocr_avail = host->pdata->get_ocr(id); -- 1.7.0.4 -- To unsubscribe from this list: send the line "unsubscribe linux-mmc" in the body of a message to [email protected] More majordomo info at http://vger.kernel.org/majordomo-info.html
