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mmc: dw_mmc: set the supported max/min frequency

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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 <tgih.jun@samsung.com>
Tested-by: Alim Akhtar <alim.akhtar@samsung.com>
Signed-off-by: Chris Ball <cjb@laptop.org>
This commit is contained in:
Seungwon Jeon 2013-08-31 00:13:31 +09:00 committed by Chris Ball
parent 10b498419f
commit 1f44a2a557
2 changed files with 16 additions and 2 deletions
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4
Documentation/devicetree/bindings/mmc/synopsis-dw-mshc.txt
View File

@ -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;

14
drivers/mmc/host/dw_mmc.c
View File

@ -50,6 +50,9 @@
#define DW_MCI_RECV_STATUS 2
#define DW_MCI_DMA_THRESHOLD 16
#define DW_MCI_FREQ_MAX 200000000 /* unit: HZ */
#define DW_MCI_FREQ_MIN 400000 /* unit: HZ */
#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 | \
@ -1936,6 +1939,7 @@ 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);
@ -1951,8 +1955,14 @@ 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);