On 6 November 2014 07:37, Alexandre Courbot <acourbot@xxxxxxxxxx> wrote:
> On 10/30/2014 01:22 AM, Tomeu Vizoso wrote:
>>
>> The EMC clock needs some extra information for changing its rate.
>>
>> Signed-off-by: Tomeu Vizoso <tomeu.vizoso@xxxxxxxxxxxxx>
>> ---
>> .../bindings/clock/nvidia,tegra124-car.txt | 46
>> +++++++++++++++++++++-
>> 1 file changed, 44 insertions(+), 2 deletions(-)
>>
>> diff --git
>> a/Documentation/devicetree/bindings/clock/nvidia,tegra124-car.txt
>> b/Documentation/devicetree/bindings/clock/nvidia,tegra124-car.txt
>> index ded5d62..42e0588 100644
>> --- a/Documentation/devicetree/bindings/clock/nvidia,tegra124-car.txt
>> +++ b/Documentation/devicetree/bindings/clock/nvidia,tegra124-car.txt
>> @@ -19,12 +19,35 @@ Required properties :
>> In clock consumers, this cell represents the bit number in the CAR's
>> array of CLK_RST_CONTROLLER_RST_DEVICES_* registers.
>>
>> +The node should contain a "emc-timings" subnode for each supported RAM
>> type (see
>> +field RAM_CODE in register PMC_STRAPPING_OPT_A), with its unit address
>> being its
>> +RAM_CODE.
>> +
>> +Required properties for "emc-timings" nodes :
>> +- nvidia,ram-code : Should contain the value of RAM_CODE this timing set
>> + is used for.
>> +
>> +Each "emc-timings" node should contain a "timing" subnode for every
>> supported
>> +EMC clock rate. The "timing" subnodes should have the clock rate in Hz as
>> their
>> +unit address.
>
>
> This seems to be a quite liberal use of unit addresses (same in the next
> patch) - is this allowed by DT?
Well, it's not that different from using the register address. I think
it helps with readability more than an arbitrary index.
>> +
>> +Required properties for "timing" nodes :
>> +- clock-frequency : Should contain the memory clock rate to which this
>> timing
>> +relates.
>> +- nvidia,parent-clock-frequency : Should contain the rate at which the
>> current
>> +parent of the EMC clock should be running at this timing.
>> +- clocks : Must contain an entry for each entry in clock-names.
>> + See ../clocks/clock-bindings.txt for details.
>> +- clock-names : Must include the following entries:
>> + - emc-parent : the clock that should be the parent of the EMC clock at
>> this
>> +timing.
>> +
>> Example SoC include file:
>>
>> / {
>> - tegra_car: clock {
>> + tegra_car: clock@0,60006000 {
>> compatible = "nvidia,tegra124-car";
>> - reg = <0x60006000 0x1000>;
>> + reg = <0x0 0x60006000 0x0 0x1000>;
>> #clock-cells = <1>;
>> #reset-cells = <1>;
>> };
>> @@ -60,4 +83,23 @@ Example board file:
>> &tegra_car {
>> clocks = <&clk_32k> <&osc>;
>> };
>> +
>> + clock@0,60006000 {
>> + emc-timings@3 {
>> + nvidia,ram-code = <3>;
>> +
>> + timing@12750000 {
>> + clock-frequency = <12750000>;
>> + nvidia,parent-clock-frequency =
>> <408000000>;
>> + clocks = <&tegra_car TEGRA124_CLK_PLL_P>;
>> + clock-names = "emc-parent";
>> + };
>> + timing@20400000 {
>> + clock-frequency = <20400000>;
>> + nvidia,parent-clock-frequency =
>> <408000000>;
>> + clocks = <&tegra_car TEGRA124_CLK_PLL_P>;
>> + clock-names = "emc-parent";
>> + };
>> + };
>> + };
>
>
> At first it seems confusing to see a top-level node without a compatible
> property, until you realize it has already been defined before.
>
> In patch 05, you put "Example board file:" above a similar node, which is
> enough to lift that ambiguity - could you do the same here?
Oh, actually it was already in the file. I took this idea from here
for patch 05.
Thanks,
Tomeu
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