On Wed, Aug 29, 2018 at 2:05 PM Vivek Gautam
[off-list ref] wrote:

quoted

Hi Rob,


On 8/29/2018 2:04 AM, Rob Herring wrote:

quoted

On Mon, Aug 27, 2018 at 04:25:50PM +0530, Vivek Gautam wrote:

quoted

Add bindings doc for Qcom's smmu-v2 implementation.

Signed-off-by: Vivek Gautam <redacted>
Reviewed-by: Tomasz Figa <tfiga@chromium.org>
Tested-by: Srinivas Kandagatla <redacted>
---

Changes since v14:
  - This is a new patch added in v15 after noticing the new
    checkpatch warning for separate dt-bindings doc.
  - This patch also addresses comments given by Rob and Robin to add
    a list of valid values of '<soc>' in "qcom,<soc>-smmu-v2"
    compatible string.

  .../devicetree/bindings/iommu/arm,smmu.txt         | 47 ++++++++++++++++++++++
  1 file changed, 47 insertions(+)

diff --git a/Documentation/devicetree/bindings/iommu/arm,smmu.txt b/Documentation/devicetree/bindings/iommu/arm,smmu.txt
index 8a6ffce12af5..52198a539606 100644
--- a/Documentation/devicetree/bindings/iommu/arm,smmu.txt
+++ b/Documentation/devicetree/bindings/iommu/arm,smmu.txt

@@ -17,10 +17,24 @@ conditions.
                          "arm,mmu-401"
                          "arm,mmu-500"
                          "cavium,smmu-v2"
+                        "qcom,<soc>-smmu-v2", "qcom,smmu-v2"

The v2 in the compatible string is kind of redundant unless the SoC has
other SMMU types.

sdm845 has smmu-v2, and smmu-500 [1].

quoted

quoted

                    depending on the particular implementation and/or the
                    version of the architecture implemented.

+                  A number of Qcom SoCs use qcom,smmu-v2 version of the IP.
+                  "qcom,<soc>-smmu-v2" represents a soc specific compatible
+                  string that should be present along with the "qcom,smmu-v2"
+                  to facilitate SoC specific clocks/power connections and to
+                  address specific bug fixes.
+                  '<soc>' string in "qcom,<soc>-smmu-v2" should be one of the
+                  following:
+                  msm8996 - for msm8996 Qcom SoC.
+                  sdm845 - for sdm845 Qcom Soc.

Rather than all this prose, it would be simpler to just add 2 lines with
the full compatibles rather than <soc>. The <soc> thing is not going to
work when/if we move bindings to json-schema also.

then we keep adding
          "qcom,msm8996-smmu-v2", "qcom,smmu-v2"
          "qcom,msm8998-smmu-v2", "qcom,smmu-v2"
          "qcom,sdm845-smmu-v2", "qcom,smmu-v2",
and from [1]
          "qcom,sdm845-smmu-500", "arm,mmu-500", etc.
for each SoCs?

How about following diff on top of this patch?

diff --git a/Documentation/devicetree/bindings/iommu/arm,smmu.txt

b/Documentation/devicetree/bindings/iommu/arm,smmu.txt
index 52198a539606..5e6c04876533 100644

--- a/Documentation/devicetree/bindings/iommu/arm,smmu.txt
+++ b/Documentation/devicetree/bindings/iommu/arm,smmu.txt

@@ -17,23 +17,18 @@ conditions.
                         "arm,mmu-401"
                         "arm,mmu-500"
                         "cavium,smmu-v2"
-                        "qcom,<soc>-smmu-v2", "qcom,smmu-v2"
+                        "qcom,smmu-v2"

                   depending on the particular implementation and/or the
                   version of the architecture implemented.

-                  A number of Qcom SoCs use qcom,smmu-v2 version of the IP.
-                  "qcom,<soc>-smmu-v2" represents a soc specific compatible
-                  string that should be present along with the "qcom,smmu-v2"
-                  to facilitate SoC specific clocks/power connections and to
-                  address specific bug fixes.
-                  '<soc>' string in "qcom,<soc>-smmu-v2" should be one of the
-                  following:
-                  msm8996 - for msm8996 Qcom SoC.
-                  sdm845 - for sdm845 Qcom Soc.
-
-                  An example string would be -
-                  "qcom,msm8996-smmu-v2", "qcom,smmu-v2".
+                  Qcom SoCs using qcom,smmu-v2 must have soc specific
+                  compatible string attached to "qcom,smmu-v2" to take care
+                  of SoC specific clocks/power connections and to address
+                  specific bug fixes.
+                  Precisely, it should be one of the following:
+                  "qcom,msm8996-smmu-v2", "qcom,smmu-v2",
+                  "qcom,sdm845-smmu-v2", "qcom,smmu-v2".