From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id F190F3CB2D9; Mon, 20 Apr 2026 13:17:43 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=10.30.226.201 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1776691064; cv=none; b=p4Mm6i4bI8DP26ewDAyWShHAs67yGd/bUBact1ecsnPXNo0Gouvmov11UPKMBUbevcDuky7vlEeaa66wLdYN4txe+ZOz1p/qK+ZelZvVIa3h8psNf28eGarUzFHdbHrceDZJh+P4nupgGPr65V7wRXmvZfFA83BOPdQqPBxSpmg= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1776691064; c=relaxed/simple; bh=kgfq54QGG2g58urvUeBUMahf9u493TsnAKZki1DT03Q=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=lj5sfEJ01occkvimGeuaNuMVEjMV1zdzcG3FyTaQY9j+02o4rYsT+SUxY9FX5N89kz7d6pGQR72dO70jfoIwXq+kF92umNa0rWtFtK4P6zyyLdC1e5Pk1FgVxyp3LAQB15fnh6eejTWG6KFmpGG/JVZpRpYxhhR9K7ki2Zj725A= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=uiqL3gbW; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="uiqL3gbW" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 7C336C2BCB4; Mon, 20 Apr 2026 13:17:42 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1776691063; bh=kgfq54QGG2g58urvUeBUMahf9u493TsnAKZki1DT03Q=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=uiqL3gbWk+jJbU+nFLsHg44O6xpCrh75V1QgBnS3AGwB/Xf8GL3waJ60JGIPwnI6C IpL0X/ChLtZCwgQxNnz+K59M/k/MtqljVmHFEl8vFVlfjca7Iclj6zrfvFzjhs8lwh 4bTBoFMEj0GmYj8WTxpVrut/hdK3vsJV+AnwZfaezpdNBPwKd/iCfUGksk3oQWgksg j+5PmHNuNQxp9SLzUAjOudPtQ25efXleufy+xPUdw2QoxOJQNSDfMApkQtLdA/0zYK jNREtu2fxD0QkaikZa+ZVkzWp30c9yfPmFaVpjey2y2X+g2shxSaq4YFp+ah1GdIUL OcUdC0VAqXrIA== From: Sasha Levin To: patches@lists.linux.dev, stable@vger.kernel.org Cc: Dawei Liu , Guenter Roeck , Sasha Levin , jdelvare@suse.com, corbet@lwn.net, linux-hwmon@vger.kernel.org, linux-doc@vger.kernel.org, linux-kernel@vger.kernel.org Subject: [PATCH AUTOSEL 7.0-6.18] hwmon: (pmbus/isl68137) Add support for Renesas RAA228942 and RAA228943 Date: Mon, 20 Apr 2026 09:08:58 -0400 Message-ID: <20260420131539.986432-72-sashal@kernel.org> X-Mailer: git-send-email 2.53.0 In-Reply-To: <20260420131539.986432-1-sashal@kernel.org> References: <20260420131539.986432-1-sashal@kernel.org> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 X-stable: review X-Patchwork-Hint: Ignore X-stable-base: Linux 7.0 Content-Transfer-Encoding: 8bit From: Dawei Liu [ Upstream commit 7c760db74c9f30da7281c7f450d0676ec78ec3e6 ] Add I2C device IDs for Renesas RAA228942 and RAA228943. At the Linux PMBus hwmon interface level currently supported by this driver, these devices are compatible with the existing 2-rail non-TC controllers, so devicetree will use fallback compatibles and no dedicated OF match entries are needed. Signed-off-by: Dawei Liu Link: https://lore.kernel.org/r/20260325090208.857-3-dawei.liu.jy@renesas.com Signed-off-by: Guenter Roeck Signed-off-by: Sasha Levin --- LLM Generated explanations, may be completely bogus: Now I have all the information needed for a complete analysis. Let me compile the findings. --- ## PHASE 1: COMMIT MESSAGE FORENSICS **Step 1.1: Subject Line** - Subsystem: `hwmon: (pmbus/isl68137)` - Action verb: "Add support" - Summary: Add I2C device IDs for two new Renesas voltage regulators (RAA228942 and RAA228943) - Record: This is a device ID addition, not a bug fix. **Step 1.2: Tags** - Signed-off-by: Dawei Liu (author, Renesas employee) - Link: lore.kernel.org mail link - Signed-off-by: Guenter Roeck (hwmon subsystem maintainer - accepted the patch) - No Fixes: tag (expected for candidates) - No Cc: stable (expected for candidates) - No Reported-by, Tested-by, or Reviewed-by **Step 1.3: Commit Body** - States that these devices "are compatible with the existing 2-rail non-TC controllers" - Explicitly says "devicetree will use fallback compatibles and no dedicated OF match entries are needed" - This is a pure hardware enablement addition **Step 1.4: Hidden Bug Fix?** - No. This is not a hidden bug fix. It is straightforward device ID addition. ## PHASE 2: DIFF ANALYSIS **Step 2.1: Inventory** - `Documentation/hwmon/isl68137.rst`: +20 lines (documentation for two new devices) - `drivers/hwmon/pmbus/isl68137.c`: +2 lines (two I2C device ID table entries) - Total: +22 lines, 0 removed - Scope: Trivially small, single-file code change + docs **Step 2.2: Code Flow** - Two entries added to the `raa_dmpvr_id[]` I2C device ID table: - `{"raa228942", raa_dmpvr2_2rail_nontc}` - `{"raa228943", raa_dmpvr2_2rail_nontc}` - These use the existing `raa_dmpvr2_2rail_nontc` variant, which was introduced in commit 51fb91ed5a6fa (v5.10 era). The variant disables `TEMP3` and configures 2-page mode. - No new code paths, no new functions, no logic changes **Step 2.3: Bug Mechanism** - Category: Hardware device ID addition (exception category h) - Without these IDs, the kernel cannot bind the existing ISL68137 PMBus driver to these Renesas parts **Step 2.4: Fix Quality** - Obviously correct: merely adding two string/enum pairs to an existing table - Minimal and surgical - Zero regression risk: only affects systems with these specific I2C devices - No new code paths, APIs, or behavioral changes ## PHASE 3: GIT HISTORY **Step 3.1: Blame** - The `raa_dmpvr_id[]` table has been present since commit f621d61fd59f4 (2020). The `raa_dmpvr2_2rail_nontc` variant was added in commit 51fb91ed5a6fa (2020, v5.10 era). - Both are present in all active stable trees (5.10+, 5.15+, 6.1+, 6.6+) **Step 3.2: Fixes Tag** - No Fixes: tag (not applicable - this is a device ID addition, not a bug fix) **Step 3.3: File History** - Prior identical-pattern commit: 2190ad55a601d added RAA228244 and RAA228246 in the same manner. This was a v6.18/6.19 timeframe commit. - The pattern of adding new Renesas device IDs to this driver is well established. **Step 3.4: Author** - Dawei Liu is a Renesas employee (dawei.liu.jy@renesas.com), appropriate for submitting Renesas device support. **Step 3.5: Dependencies** - No dependencies. The `raa_dmpvr2_2rail_nontc` enum value and its case statement already exist in stable trees back to 5.10. ## PHASE 4: MAILING LIST RESEARCH **Step 4.1-4.5:** Lore is behind bot protection and cannot be fetched. However, the Link: tag confirms the patch was submitted via the standard process and accepted by hwmon maintainer Guenter Roeck. The `b4 dig` of the prior similar commit (2190ad55a601d) confirmed it was part of a normal patch series accepted through the standard hwmon tree. ## PHASE 5: CODE SEMANTIC ANALYSIS **Step 5.1-5.5:** - The only code change is adding entries to a static `struct i2c_device_id` table. - When the I2C subsystem finds a device matching `"raa228942"` or `"raa228943"`, it will call `isl68137_probe()` with the `raa_dmpvr2_2rail_nontc` variant. - The `raa_dmpvr2_2rail_nontc` case (lines 413-416) simply disables TEMP3, falls through to the 2-rail handler. This is well-tested code used by RAA228228, RAA228244, and RAA228246. - No new code paths are created. ## PHASE 6: STABLE TREE ANALYSIS **Step 6.1:** The driver exists in all active stable trees (5.10+). The `raa_dmpvr2_2rail_nontc` variant exists since 5.10. **Step 6.2:** The patch adds 2 lines to the I2C ID table and documentation. It will apply cleanly or with trivial context adjustments (the table is in alphabetical order). **Step 6.3:** No related fixes already in stable for these specific devices. ## PHASE 7: SUBSYSTEM CONTEXT **Step 7.1:** `drivers/hwmon/pmbus` - hardware monitoring for PMBus voltage regulators. Criticality: PERIPHERAL (specific hardware). However, PMBus voltage regulators are used in servers and embedded systems where stable kernels are common. **Step 7.2:** Actively maintained by Guenter Roeck, with regular device ID additions. ## PHASE 8: IMPACT AND RISK **Step 8.1:** Affects users of Renesas RAA228942/RAA228943 hardware specifically. **Step 8.2:** Without these IDs, the driver cannot bind to the hardware at all. Users with this hardware have no workaround on stable kernels. **Step 8.3:** Failure mode without fix: hardware is completely inaccessible. Severity: MEDIUM (functional but not crash/corruption). **Step 8.4:** - Benefit: Enables hardware monitoring for users with these specific Renesas voltage regulators on stable kernels. - Risk: Essentially zero. Two table entries using an existing, well- tested variant. - Ratio: Very favorable benefit/risk. ## PHASE 9: FINAL SYNTHESIS **Evidence FOR backporting:** - Device ID addition to existing driver - explicitly allowed exception category - Trivially small (2 lines of code) - Uses existing, well-tested variant (`raa_dmpvr2_2rail_nontc`) present since v5.10 - Zero regression risk - Accepted by subsystem maintainer (Guenter Roeck) - Author is from the chip vendor (Renesas) - Enables real hardware for real users **Evidence AGAINST backporting:** - Not a bug fix - purely hardware enablement - Affects only users with these specific Renesas parts (narrow audience) **Stable Rules Checklist:** 1. Obviously correct? **YES** - trivial table addition 2. Fixes a real bug? **No** - but device ID additions are an explicit exception 3. Important? Moderately - enables hardware for users who have it 4. Small and contained? **YES** - 2 lines of code + docs 5. No new features/APIs? **YES** - no new features, just ID binding 6. Can apply to stable? **YES** - clean apply expected **Exception Category:** Device ID addition to existing driver - this is one of the explicitly listed categories that ARE allowed in stable despite being "additions." ## Verification - [Phase 1] Parsed tags: Signed-off-by from Renesas author + hwmon maintainer Guenter Roeck; Link to lore - [Phase 2] Diff analysis: +2 lines in I2C ID table (raa228942/raa228943 as raa_dmpvr2_2rail_nontc), +20 lines docs - [Phase 3] git blame: ID table present since f621d61fd59f4 (2020); nontc variant since 51fb91ed5a6fa (2020, v5.10 era) - [Phase 3] git tag --contains 51fb91ed5a6fa: present in p-5.10, p-5.15, all active stable trees - [Phase 3] git log: prior identical-pattern commit 2190ad55a601d (RAA228244/RAA228246) confirmed - [Phase 3] git log --author: author is Renesas employee - [Phase 4] b4 dig: lore blocked by bot protection; confirmed standard hwmon maintainer acceptance via prior similar commit - [Phase 5] Code reading: raa_dmpvr2_2rail_nontc case at line 413 disables TEMP3, falls through to 2-rail; well-tested - [Phase 6] Verified existing variant in tree at lines 76, 413, 498-500, 549-551 - [Phase 6] No raa228942/raa228943 references found anywhere in current tree (grep confirmed) - [Phase 8] Risk: zero regression potential from static table entry addition - UNVERIFIED: Could not read lore discussion due to bot protection This is a textbook device ID addition - the simplest and safest type of stable backport. Two lines adding I2C device IDs to an existing driver using an existing, well-tested variant. Zero regression risk, enables hardware for real users. **YES** Documentation/hwmon/isl68137.rst | 20 ++++++++++++++++++++ drivers/hwmon/pmbus/isl68137.c | 2 ++ 2 files changed, 22 insertions(+) diff --git a/Documentation/hwmon/isl68137.rst b/Documentation/hwmon/isl68137.rst index e77f582c28505..0ce20d09164fc 100644 --- a/Documentation/hwmon/isl68137.rst +++ b/Documentation/hwmon/isl68137.rst @@ -394,6 +394,26 @@ Supported chips: Provided by Renesas upon request and NDA + * Renesas RAA228942 + + Prefix: 'raa228942' + + Addresses scanned: - + + Datasheet: + + Provided by Renesas upon request and NDA + + * Renesas RAA228943 + + Prefix: 'raa228943' + + Addresses scanned: - + + Datasheet: + + Provided by Renesas upon request and NDA + * Renesas RAA229001 Prefix: 'raa229001' diff --git a/drivers/hwmon/pmbus/isl68137.c b/drivers/hwmon/pmbus/isl68137.c index 3e3a887aad050..c8930f2d54237 100644 --- a/drivers/hwmon/pmbus/isl68137.c +++ b/drivers/hwmon/pmbus/isl68137.c @@ -498,6 +498,8 @@ static const struct i2c_device_id raa_dmpvr_id[] = { {"raa228228", raa_dmpvr2_2rail_nontc}, {"raa228244", raa_dmpvr2_2rail_nontc}, {"raa228246", raa_dmpvr2_2rail_nontc}, + {"raa228942", raa_dmpvr2_2rail_nontc}, + {"raa228943", raa_dmpvr2_2rail_nontc}, {"raa229001", raa_dmpvr2_2rail}, {"raa229004", raa_dmpvr2_2rail}, {"raa229141", raa_dmpvr2_2rail_pmbus}, -- 2.53.0