linux-kernel - Re: [Patch v2 1/8] dt/bindings: firmware: Add Qualcomm SCM binding

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Date:	Mon, 25 Apr 2016 21:14:59 -0500
From:	Andy Gross <andy.gross@...aro.org>
To:	Stephen Boyd <sboyd@...eaurora.org>
Cc:	linux-arm-msm <linux-arm-msm@...r.kernel.org>,
	linux-arm-kernel@...ts.infradead.org, linux-kernel@...r.kernel.org,
	devicetree@...r.kernel.org, jilai wang <jilaiw@...eaurora.org>
Subject: Re: [Patch v2 1/8] dt/bindings: firmware: Add Qualcomm SCM binding

On 25 April 2016 at 20:49, Stephen Boyd <sboyd@...eaurora.org> wrote:
> On 04/25, Andy Gross wrote:
>> This patch adds the device tree support for the Qualcomm SCM firmware.
>>
>> Signed-off-by: Andy Gross <andy.gross@...aro.org>
>> ---
>>  .../devicetree/bindings/firmware/qcom,scm.txt      | 28 ++++++++++++++++++++++
>>  1 file changed, 28 insertions(+)
>>  create mode 100644 Documentation/devicetree/bindings/firmware/qcom,scm.txt
>>
>> diff --git a/Documentation/devicetree/bindings/firmware/qcom,scm.txt b/Documentation/devicetree/bindings/firmware/qcom,scm.txt
>> new file mode 100644
>> index 0000000..a679a87
>> --- /dev/null
>> +++ b/Documentation/devicetree/bindings/firmware/qcom,scm.txt
>> @@ -0,0 +1,28 @@
>> +QCOM Secure Channel Manager (SCM)
>> +
>> +Qualcomm processors include an interface to communicate to the secure firmware.
>> +This interface allows for clients to request different types of actions.  These
>> +can include CPU power up/down, HDCP requests, loading of firmware, and other
>> +assorted actions.
>> +
>> +Required properties:
>> +- compatible: must contain one of the following:
>> + * "qcom,scm-apq8064" for APQ8064
>> + * "qcom,scm-apq8084" for APQ8084
>> + * "qcom,scm-msm8916" for MSM8916
>> + * "qcom,scm-msm8974" for MSM8974
>
> Do we need to keep adding these into the driver for every SoC
> that we support? My understanding is apq8064 can be the one that
> requires one clk, and msm8974 can be the one that requires three.
> The driver can just have those two compatibles for now, and we
> can keep adding compatibles here for the different SoCs, but
> really we don't care, that's just to save ourselves if something
> pops up and needs a workaround.
>
> It will certainly look weird if it's firmware that's compatible
> with qcom,scm-msm8974 but on an apq8084, so perhaps something
> more generic like, qcom-scm-v1 and qcom,scm-v2 can be used as the
> generic compatible in the driver:
>
>         compatible = "qcom,scm-apq8064", "qcom,scm-v1";
>
>         vs.
>
>         compatible = "qcom,scm-apq8084", "qcom,scm-v2";
>
> ?
>
> I just want to avoid the constant SoC churn update here if we can.

Right.  We can certainly do it that way.  Its just that the v1/v2
aren't the real versions.  What if we did qcom,scm vs
qcom,scm-apq8064?