Re: [PATCH v3 12/14] dt-bindings: msm/dp: Add bindings for HDCP registers

On Mon, Oct 04, 2021 at 02:58:41PM -0500, Bjorn Andersson wrote:

On Fri 01 Oct 10:11 CDT 2021, Sean Paul wrote:

...

From: Sean Paul seanpaul@chromium.org

This patch adds the bindings for the MSM DisplayPort HDCP registers which are required to write the HDCP key into the display controller as well as the registers to enable HDCP authentication/key exchange/encryption.

We'll use a new compatible string for this since the fields are optional.

I don't think you need a new compatible, in particular since I presume we should use the hdcp compatible in all platforms? Or is there a reason for not picking that one?

Instead I suggest that you simply do minItems: 1, maxItems: 3 and detect which of the two cases you have in the driver.

Thanks for your review, Bjorn! I had done this in v2 (see [1] & [2]), but it was suggested that a new compatible would be better. I'll change it back to this method rebased on top of your changes.

Sean

[1]- https://patchwork.freedesktop.org/patch/454066/?series=94712&rev=1 [2]- https://patchwork.freedesktop.org/patch/454068/?series=94712&rev=1

PS. I hope to get https://lore.kernel.org/linux-arm-msm/20211001174400.981707-1-bjorn.andersso... landed before we add these new optional regions...

Regards, Bjorn

...

Cc: Rob Herring robh@kernel.org Cc: Stephen Boyd swboyd@chromium.org Signed-off-by: Sean Paul seanpaul@chromium.org Link: https://patchwork.freedesktop.org/patch/msgid/20210913175747.47456-13-sean@p... #v1 Link: https://patchwork.freedesktop.org/patch/msgid/20210915203834.1439-13-sean@po... #v2

Changes in v2: -Drop register range names (Stephen) -Fix yaml errors (Rob) Changes in v3: -Add new compatible string for dp-hdcp -Add descriptions to reg -Add minItems/maxItems to reg

-Make reg depend on the new hdcp compatible string

Disclaimer: I really don't know if this is the right way to approach this. I tried using examples from other bindings, but feedback would be very much welcome on how I could add the optional register ranges.

.../bindings/display/msm/dp-controller.yaml | 34 ++++++++++++++++--- 1 file changed, 30 insertions(+), 4 deletions(-)

diff --git a/Documentation/devicetree/bindings/display/msm/dp-controller.yaml b/Documentation/devicetree/bindings/display/msm/dp-controller.yaml index 64d8d9e5e47a..a176f97b2f4c 100644 --- a/Documentation/devicetree/bindings/display/msm/dp-controller.yaml +++ b/Documentation/devicetree/bindings/display/msm/dp-controller.yaml @@ -17,9 +17,10 @@ properties: compatible: enum: - qcom,sc7180-dp

•  - qcom,sc7180-dp-hdcp
  
  

• reg:
• maxItems: 1

• # See compatible-specific constraints below.

• reg: true

  interrupts: maxItems: 1

@@ -89,6 +90,29 @@ required:

• power-domains
• ports

+allOf:

• • if:

•  properties:
  

•    compatible:
  

•      contains:
  

•        const: qcom,sc7180-dp-hdcp
  

• then:

•  properties:
  

•    reg:
  

•      minItems: 3
  

•      maxItems: 3
  

•      items:
  

•        - description: Registers for base DP functionality
  

•        - description: (Optional) Registers for HDCP device key injection
  

•        - description: (Optional) Registers for HDCP TrustZone interaction
  

• else:

•  properties:
  

•    reg:
  

•      minItems: 1
  

•      maxItems: 1
  

•      items:
  

•        - description: Registers for base DP functionality
  

additionalProperties: false

examples: @@ -99,8 +123,10 @@ examples: #include <dt-bindings/power/qcom-rpmpd.h>

 displayport-controller@ae90000 {

•    compatible = "qcom,sc7180-dp";
  

•    reg = <0xae90000 0x1400>;
  

•    compatible = "qcom,sc7180-dp-hdcp";
  

•    reg = <0 0x0ae90000 0 0x1400>,
  

•          <0 0x0aed1000 0 0x174>,
  

•          <0 0x0aee1000 0 0x2c>;
     interrupt-parent = <&mdss>;
     interrupts = <12>;
     clocks = <&dispcc DISP_CC_MDSS_AHB_CLK>,
  

-- Sean Paul, Software Engineer, Google / Chromium OS