On 9/19/19 9:28 AM, Krzysztof Kozlowski wrote:
> On Thu, 19 Sep 2019 at 08:49, Lukasz Luba <l.luba@xxxxxxxxxxxxxxxxxxx> wrote:
>>
>> Hi Krzysztof,
>>
>> On 9/18/19 8:51 PM, Krzysztof Kozlowski wrote:
>>> On Mon, 16 Sep 2019 at 12:07, Lukasz Luba <l.luba@xxxxxxxxxxxxxxxxxxx> wrote:
>>>>
>>>> Add compatible for Samsung k3qf2f20db LPDDR3 memory bindings.
>>>> Introduce minor fixes in the old documentation.
>>>>
>>>> Signed-off-by: Lukasz Luba <l.luba@xxxxxxxxxxxxxxxxxxx>
>>>> ---
>>>> Documentation/devicetree/bindings/ddr/lpddr3.txt | 9 ++++++---
>>>> 1 file changed, 6 insertions(+), 3 deletions(-)
>>>>
>>>> diff --git a/Documentation/devicetree/bindings/ddr/lpddr3.txt b/Documentation/devicetree/bindings/ddr/lpddr3.txt
>>>> index 3b2485b84b3f..49afe794daaa 100644
>>>> --- a/Documentation/devicetree/bindings/ddr/lpddr3.txt
>>>> +++ b/Documentation/devicetree/bindings/ddr/lpddr3.txt
>>>> @@ -1,7 +1,9 @@
>>>> * LPDDR3 SDRAM memories compliant to JEDEC JESD209-3C
>>>>
>>>> Required properties:
>>>> -- compatible : Should be - "jedec,lpddr3"
>>>> +- compatible : should be one of the following:
>>>> + Generic default - "jedec,lpddr3".
>>>
>>> The convention is first compatible, then description. I gave you the
>>> example to base on - at25. Why making it different?
>>
>> I have checked at25 that you pointed me to and also checked at24, which
>> has a bit longer "compatible" section.
>>
>> I found that there are many "jedec,spi-nor" compatible devices, which I
>> thought would be a better example for my "jedec,lpddr3".
>> For example, two configurations, where you have a single labels or dual
>> (with specific device)
>> arch/arm/boot/dts/imx6dl-rex-basic.dts:
>> compatible = "sst,sst25vf016b", "jedec,spi-nor";
>> arch/arm/boot/dts/imx6q-ba16.dtsi:
>> compatible = "jedec,spi-nor";
>>
>> The 'compatible' in documentation for the "jedec,spi-nor" is slightly
>> different (similar to at24).
>> Documentation/devicetree/bindings/mtd/jedec,spi-nor.txt
>> It has a long explanation, which is also OK. So I thought that it is
>> quite flexible what you put in there.
>
> It is flexible but I see clear pattern in existing sources:
> jedec,spi-nor.txt
> compatible : May include a device-specific ..
> ...
> Supported chip names:
> at25df321a
> ...
>
> at25.txt:
> - compatible : Should be "<vendor>,<type>", and generic value "atmel,at25".
> Example "<vendor>,<type>" values:
> "anvo,anv32e61w"
> "microchip,25lc040"
>
> In these cases the doc says that "compatible should be" and then you
> have the list of values. Your example says that the compatible should
> be "Generic default" or "For Samsung 542x SoC"... :) The difference is
> slight but putting the value first is a simple and elegant solution.
> In your case one has to go to the end of sentence to find the most
> important information - the compatible value.
>
>> I have also checked Cadance QSPI controller.
>> Documentation/devicetree/bindings/mtd/cadence-quadspi.txt
>> The controller might be built-in into different vendor SoC's
>> and the "compatible" is ready to reflect it in similar fashion but
>> with a short explanation in this section.
>
> I see. I do not find this pattern as much readable as jedec-spi-nor or
> at25 therefore I mentioned them as an example to base on ("Exactly the
> same as AT24 or AT25 EEPROM bindings."). We can avoid also this entire
> discussion with YAML (which also follows approach of at25 - value
> first).
>
>> Therefore, what you see in the patch draw heavily on Cadence's qspi,
>> with a bit of inspiration from jedec,spi-nor usage.
>>
>> Should I change it to at25 "compatible" style and send next patch?
>
> Yes, please. Or go to YAML and make entire discussion obsolete.
OK I will change it to at25 style.
Regards,
Lukasz
