From e02adac7c84bf2883ce5d5a828a03871c0c1d4f9 Mon Sep 17 00:00:00 2001 From: Matthias Schiffer Date: Tue, 24 Jun 2025 12:53:34 +0200 Subject: [PATCH] checkpatch: check for comment explaining rgmii(|-rxid|-txid) PHY modes Historically, the RGMII PHY modes specified in Device Trees have been used inconsistently, often referring to the usage of delays on the PHY side rather than describing the board; many drivers still implement this incorrectly. Require a comment in Devices Trees using these modes (usually mentioning that the delay is realized on the PCB), so we can avoid adding more incorrect uses (or will at least notice which drivers still need to be fixed). Suggested-by: Andrew Lunn Signed-off-by: Matthias Schiffer Reviewed-by: Andrew Lunn Link: https://patch.msgid.link/bc112b8aa510cf9df9ab33178d122f234d0aebf7.1750756583.git.matthias.schiffer@ew.tq-group.com Signed-off-by: Paolo Abeni --- Documentation/dev-tools/checkpatch.rst | 9 +++++++++ scripts/checkpatch.pl | 12 ++++++++++++ 2 files changed, 21 insertions(+) diff --git a/Documentation/dev-tools/checkpatch.rst b/Documentation/dev-tools/checkpatch.rst index 76bd0ddb00416..d5c47e560324f 100644 --- a/Documentation/dev-tools/checkpatch.rst +++ b/Documentation/dev-tools/checkpatch.rst @@ -495,6 +495,15 @@ Comments See: https://lore.kernel.org/lkml/20131006222342.GT19510@leaf/ + **UNCOMMENTED_RGMII_MODE** + Historically, the RGMII PHY modes specified in Device Trees have been + used inconsistently, often referring to the usage of delays on the PHY + side rather than describing the board. + + PHY modes "rgmii", "rgmii-rxid" and "rgmii-txid" modes require the clock + signal to be delayed on the PCB; this unusual configuration should be + described in a comment. If they are not (meaning that the delay is realized + internally in the MAC or PHY), "rgmii-id" is the correct PHY mode. Commit message -------------- diff --git a/scripts/checkpatch.pl b/scripts/checkpatch.pl index 664f7b7a622c2..f597734d83cc0 100755 --- a/scripts/checkpatch.pl +++ b/scripts/checkpatch.pl @@ -3741,6 +3741,18 @@ sub process { } } +# Check for RGMII phy-mode with delay on PCB + if ($realfile =~ /\.(dts|dtsi|dtso)$/ && + $line =~ /^\+\s*(phy-mode|phy-connection-type)\s*=\s*"/ && + !ctx_has_comment($first_line, $linenr)) { + my $prop = $1; + my $mode = get_quoted_string($line, $rawline); + if ($mode =~ /^"rgmii(?:|-rxid|-txid)"$/) { + WARN("UNCOMMENTED_RGMII_MODE", + "$prop $mode without comment -- delays on the PCB should be described, otherwise use \"rgmii-id\"\n" . $herecurr); + } + } + # check for using SPDX license tag at beginning of files if ($realline == $checklicenseline) { if ($rawline =~ /^[ \+]\s*\#\!\s*\//) { -- 2.47.2