linux-kernel - [PATCH v2 1/3] dt-bindings: phy: cadence-torrent: Add latency properties

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Message-Id: <20230427055032.85015-2-rath@ibv-augsburg.de>
Date:   Thu, 27 Apr 2023 07:50:30 +0200
From:   Dominic Rath <rath@...-augsburg.de>
To:     robh+dt@...nel.org, krzysztof.kozlowski+dt@...aro.org,
        tjoseph@...ence.com
Cc:     bhelgaas@...gle.com, lpieralisi@...nel.org, nm@...com,
        vigneshr@...com, devicetree@...r.kernel.org,
        linux-kernel@...r.kernel.org, linux-pci@...r.kernel.org,
        christian.gmeiner@...il.com, bahle@...-augsburg.de,
        Dominic Rath <rath@...-augsburg.de>
Subject: [PATCH v2 1/3] dt-bindings: phy: cadence-torrent: Add latency properties

From: Alexander Bahle <bahle@...-augsburg.de>

Add "tx-phy-latency-ps" and "rx-phy-latency-ps" DT bindings for
setting the PCIe PHY latencies.
The properties expect a list of uint32 PHY latencies in picoseconds for
every supported speed starting at PCIe Gen1, e.g.:

  tx-phy-latency-ps = <100000 200000>; /* Gen1: 100ns, Gen2: 200ns */
  rx-phy-latency-ps = <150000 250000>; /* Gen1: 150ns, Gen2: 250ns */

Signed-off-by: Alexander Bahle <bahle@...-augsburg.de>
Signed-off-by: Dominic Rath <rath@...-augsburg.de>
---
 .../bindings/phy/phy-cadence-torrent.yaml     | 20 +++++++++++++++++++
 1 file changed, 20 insertions(+)

diff --git a/Documentation/devicetree/bindings/phy/phy-cadence-torrent.yaml b/Documentation/devicetree/bindings/phy/phy-cadence-torrent.yaml
index 2ad1faadda2a..93228a304395 100644
--- a/Documentation/devicetree/bindings/phy/phy-cadence-torrent.yaml
+++ b/Documentation/devicetree/bindings/phy/phy-cadence-torrent.yaml
@@ -126,6 +126,24 @@ patternProperties:
         enum: [2160, 2430, 2700, 3240, 4320, 5400, 8100]
         default: 8100
 
+      tx-phy-latency-ps:
+        description:
+          The PHY latencies for the TX direction applied to PCIe PTM timestamps. Most
+          PCIe PHYs have asynchronous latencies for their RX and TX paths. To obtain
+          accurate PTM timestamps, the PCIe PTM specification requires that the time
+          at which the first serial bit is present on the serial lines be taken.
+          Should contain picosecond latency values for each supported speed,
+          starting with Gen1 latency.
+
+      rx-phy-latency-ps:
+        description:
+          The PHY latencies for the RX direction applied to the PTM timestamps. Most
+          PCIe PHYs have asynchronous latencies for their RX and TX paths. To obtain
+          accurate PTM timestamps, the PCIe PTM specification requires that the time
+          at which the first serial bit is present on the serial lines be taken.
+          Should contain picosecond latency values for each supported speed,
+          starting with Gen1 latency.
+
     required:
       - reg
       - resets
@@ -203,6 +221,8 @@ examples:
                 cdns,phy-type = <PHY_TYPE_PCIE>;
                 cdns,num-lanes = <2>;
                 cdns,ssc-mode = <CDNS_SERDES_NO_SSC>;
+                tx-phy-latency-ps = <138800 69400>;
+                rx-phy-latency-ps = <185200 92600>;
             };
 
             phy@2 {
-- 
2.36.0