Hi Rob / Kishon,

-----Original Message-----
From: Rob Herring <robh@kernel.org>
Sent: Friday, December 11, 2020 10:32 PM
To: Athani Nadeem Ladkhan <redacted>
Cc: Tom Joseph <redacted>; Lorenzo Pieralisi
[off-list ref]; Bjorn Helgaas [off-list ref]; PCI
[off-list ref]; linux-kernel@vger.kernel.org; Kishon Vijay
Abraham I [off-list ref]; devicetree@vger.kernel.org; Milind Parab
[off-list ref]; Swapnil Kashinath Jakhade
[off-list ref]; Parshuram Raju Thombare
[off-list ref]
Subject: Re: [PATCH v4 1/2] dt-bindings: pci: Retrain Link to work around
Gen2 training defect.

EXTERNAL MAIL


On Fri, Dec 11, 2020 at 9:03 AM Nadeem Athani [off-list ref]
wrote:

quoted

Cadence controller will not initiate autonomous speed change if
strapped as Gen2. The Retrain Link bit is set as quirk to enable this speed

change.

quoted

Adding a quirk flag based on a new compatible string.

Signed-off-by: Nadeem Athani <redacted>
---
 Documentation/devicetree/bindings/pci/cdns,cdns-pcie-host.yaml | 4
+++-
 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git
a/Documentation/devicetree/bindings/pci/cdns,cdns-pcie-host.yaml
b/Documentation/devicetree/bindings/pci/cdns,cdns-pcie-host.yaml
index 293b8ec318bc..204d78f9efe3 100644

--- a/Documentation/devicetree/bindings/pci/cdns,cdns-pcie-host.yaml
+++ b/Documentation/devicetree/bindings/pci/cdns,cdns-pcie-host.yaml

@@ -15,7 +15,9 @@ allOf:

 properties:
   compatible:
-    const: cdns,cdns-pcie-host
+    enum:
+        - cdns,cdns-pcie-host
+        - cdns,cdns-pcie-host-quirk-retrain

So, we'll just keep adding quirk strings on to the compatible? I don't think so.
Compatible strings should map to a specific implementation/platform and
quirks can then be implied from them. This is the only way we can implement
quirks in the OS without firmware
(DT) changes.

Ok, I will change the compatible string to " ti,j721e-pcie-host" in place of  " cdns,cdns-pcie-host-quirk-retrain" .
@Kishon Vijay Abraham I: Is this fine? Or will you suggest an appropriate name?

Nadeem

Rob