Messages in this thread Patch in this message | | | Date | Fri, 7 Nov 2014 14:31:19 +0900 | From | Alexandre Courbot <> | Subject | Re: [PATCH v3 04/13] of: document new emc-timings subnode in nvidia,tegra124-car |
| |
On 11/07/2014 12:12 AM, Rob Herring wrote: > On Thu, Nov 6, 2014 at 12:37 AM, Alexandre Courbot <acourbot@nvidia.com> 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@collabora.com> >>> --- >>> .../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? > > No, unit address should match a reg property.
Mmm, would you have any suggestion as to how this can be fixed? Right now what I can think of is either to replace the "clock-frequency" property by "reg" (which would be confusing), or to use a different naming scheme, e.g. timing-12750000. IIUC the naming is not essential for properly parsing these nodes, so maybe the second solution is the way to go?
> >>> + >>> +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 { > > The comma here is wrong. Commas should be used when you have something > like PCI bus:dev:func for addressing. > >>> compatible = "nvidia,tegra124-car"; >>> - reg = <0x60006000 0x1000>; >>> + reg = <0x0 0x60006000 0x0 0x1000>; > > The number of cell's is really irrelevant to the example. > >>> #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"; > > Why do you need both clocks and hardcoded values? clock-frequency is > the desired freq you want to set TEGRA124_CLK_PLL_P to?
That would be nvidia,parent-clock-frequency IIUC, while clock-frequency is the resulting EMC clock.
> > The clocks property really belongs as part of the memory controller > node or a memory device node.
I would tend to agree here. Tomeu, does it make sense to move these properties to the EMC driver instead?
| |