mmc: dw_mmc: set the supported max/min frequency

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>

1 files changed, 4 insertions, 0 deletions

diff --git a/Documentation/devicetree/bindings/mmc/synopsis-dw-mshc.txt b/Documentation/devicetree/bindings/mmc/synopsis-dw-mshc.txt
index ae5f8e89e84..fdbf6863b00 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;