* [PATCH AUTOSEL 7.0-5.10] clk: qcom: rcg2: expand frac table for mdss_pixel_clk_src
[not found] <20260428104133.2858589-1-sashal@kernel.org>
@ 2026-04-28 10:41 ` Sasha Levin
2026-04-28 10:41 ` [PATCH AUTOSEL 7.0-5.15] dt-bindings: clock: qcom,gcc-sc8180x: Add missing GDSCs Sasha Levin
1 sibling, 0 replies; 2+ messages in thread
From: Sasha Levin @ 2026-04-28 10:41 UTC (permalink / raw)
To: patches, stable
Cc: Pengyu Luo, Taniya Das, Dmitry Baryshkov, Bjorn Andersson,
Sasha Levin, agross, konrad.dybcio, mturquette, sboyd,
linux-arm-msm, linux-clk, linux-kernel
From: Pengyu Luo <mitltlatltl@gmail.com>
[ Upstream commit 0f5c8f03d990f9be9908a08a701c324e113554d2 ]
Recently, when testing 10-bit dsi C-PHY panel, clks are different
from the usual. (dsi0_phy_pll_out_dsiclk's parent is dsi0_pll_bit_clk
now (dsiclk_sel = 0)) And we failed to set dsiclk's children.
dsi_link_clk_set_rate_6g: Set clk rates: pclk=172992000, byteclk=108120000
byteclk was set first to 108120000, so the vco rate was set to
108120000 * 7 * 1 * 1 = 756840000. When we was trying to set
172992000 on mdss_pixel_clk_src later.
Since there was no matched ratio, we failed to set it. And dsiclk
divider ratio was set to 15:1 (wrong cached register value 0xf and
didn't update), we finally got 50455997, apparently wrong.
dsi0vco_clk 1 1 0 756839941
dsi0_pll_out_div_clk 1 1 0 756839941
dsi0_pll_post_out_div_clk 0 0 0 216239983
dsi0_pll_bit_clk 2 2 0 756839941
dsi0_phy_pll_out_dsiclk 2 2 0 50455997
disp_cc_mdss_pclk1_clk_src 1 1 0 50455997
dsi0_pll_by_2_bit_clk 0 0 0 378419970
dsi0_phy_pll_out_byteclk 2 2 0 108119991
disp_cc_mdss_byte1_clk_src 2 2 0 108119991
Downstream clk_summary shows the mdss_pixel_clk_src support the
ratio(35:16)
dsi0_phy_pll_out_dsiclk 2 2 0 378420000
disp_cc_mdss_pclk1_clk_src 1 1 0 172992000
dsi0_phy_pll_out_byteclk 2 2 0 108120000
disp_cc_mdss_byte1_clk_src 2 2 0 108120000
After checking downstream source, 15:4 also seems to be supported,
add them two.
Signed-off-by: Pengyu Luo <mitltlatltl@gmail.com>
Reviewed-by: Taniya Das <taniya.das@oss.qualcomm.com>
Reviewed-by: Dmitry Baryshkov <dmitry.baryshkov@oss.qualcomm.com>
Link: https://lore.kernel.org/r/20260321095029.2259489-1-mitltlatltl@gmail.com
Signed-off-by: Bjorn Andersson <andersson@kernel.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
LLM Generated explanations, may be completely bogus:
Now I have all the information I need to complete this analysis.
## Phase 1: COMMIT MESSAGE FORENSICS
**Step 1.1 - Parse subject line:**
- Subsystem: `clk: qcom: rcg2:`
- Action verb: "expand" (non-standard fix verb, but describes adding
entries)
- Record: Qualcomm Root Clock Generator 2 driver - expand fractional
ratio table for MDSS pixel clock source
**Step 1.2 - Parse tags:**
- Reviewed-by: Taniya Das <taniya.das@oss.qualcomm.com> (Qualcomm clock
expert, original author of prior frac-table update b527358cb4cd5)
- Reviewed-by: Dmitry Baryshkov <dmitry.baryshkov@oss.qualcomm.com> (msm
subsystem maintainer)
- Link: lore.kernel.org reference to discussion
- Signed-off-by: Bjorn Andersson <andersson@kernel.org> (Qualcomm SoC
maintainer, applied it)
- **NO** Fixes: tag (expected absence - this is why it's being reviewed)
- **NO** Cc: stable (expected absence)
- **NO** Reported-by: (author found it while testing)
**Step 1.3 - Analyze commit body:**
- Bug: When using a 10-bit DSI C-PHY panel with `pclk=172992000,
byteclk=108120000`, `mdss_pixel_clk_src` fails to find a matching
ratio in `frac_table_pixel[]`.
- Failure mode: `clk_pixel_determine_rate()` returns `-EINVAL`, the
divider register keeps a stale cached value (0xf = 15:1), so actual
pclk becomes ~50.4 MHz instead of required ~173 MHz — a ~3.4x wrong
clock rate. Display output is corrupted/broken.
- Root cause: Table lacks the 16/35 and 4/15 ratios that downstream
Qualcomm driver supports.
- Record: concrete runtime bug on real hardware; downstream driver
carries the needed ratios.
**Step 1.4 - Hidden fix detection:** Subject says "expand" but the body
clearly documents a failure mode. This is a bug fix disguised as an
enhancement. The "expand" verb hides that `clk_set_rate()` completely
fails without it.
## Phase 2: DIFF ANALYSIS
**Step 2.1 - Inventory:** 1 file (`drivers/clk/qcom/clk-rcg2.c`), +2 /
-0 lines. Single-file surgical change.
**Step 2.2 - Code flow:**
- Before: `frac_table_pixel[] = { {3,8}, {2,9}, {4,9}, {1,1}, {2,3}, {}
}`
- After: adds `{16,35}` and `{4,15}` before the sentinel
- Only affects `clk_pixel_determine_rate()` and `clk_pixel_set_rate()`
iteration logic
**Step 2.3 - Bug mechanism:** Hardware workaround/enablement category.
The table defines numerator/denominator pairs used to compute parent
rate requests. Without the new entries, the iteration loop falls off the
end and returns `-EINVAL` for specific legitimate hardware
configurations.
**Step 2.4 - Fix quality:**
- Obviously correct: pure data table addition, cannot affect previously
working cases.
- Cannot cause regression: iteration checks each entry in order, new
entries only kick in when existing ones don't match.
- No risk of deadlock, UAF, etc.
## Phase 3: GIT HISTORY INVESTIGATION
**Step 3.1 - Blame:**
- `frac_table_pixel[]` was introduced by `99cbd064b059f` ("clk: qcom:
Support display RCG clocks", May 2014)
- Entry `{2, 3}` was added by `b527358cb4cd5` (Feb 2022, Taniya Das)
with a `Fixes:` tag
**Step 3.2 - No Fixes: tag to follow.** The missing ratios have
effectively been absent since original commit `99cbd064b059f` (2014,
v3.17-era). Code exists in every active stable tree.
**Step 3.3 - Related file history:** Prior similar fix (`b527358cb4cd5`,
"Update the frac table for pixel clock") added a single entry and was
backported broadly. Same author context (Taniya Das reviewed both).
**Step 3.4 - Author:** Pengyu Luo is a regular contributor to qcom
subsystem with multiple DSI-related fixes (`e4eb11b34d6c8`,
`ac47870fd7955`, `fd941c787cbb4`). Patch reviewed by actual subsystem
experts.
**Step 3.5 - Dependencies:** Standalone, self-contained. No
prerequisites.
## Phase 4: MAILING LIST RESEARCH
**Step 4.1 - `b4 dig -c 0f5c8f03d990f`:** Found thread at `https://lore.
kernel.org/all/20260321095029.2259489-1-mitltlatltl@gmail.com/`. Single-
patch, v1 only, applied as-is by Bjorn Andersson with "Applied,
thanks!".
**Step 4.2 - Reviewers:** Taniya Das (Qualcomm clock expert), Dmitry
Baryshkov (msm maintainer), Konrad Dybcio (Qualcomm engineer). Proper
maintainer review.
**Step 4.3 - Discussion:** Konrad asked a clarifying question about
whether these divider pairs are needed at all; Dmitry pointed to the
Qualcomm downstream commit `f7aec4359448d25c8a8d21ad8e8733d61f6b69ab`
confirming the ratios come from the vendor reference code. No NAK, no
concerns about stability.
**Step 4.4 - Series context:** Not part of a series.
**Step 4.5 - Stable discussion:** None found in the thread.
## Phase 5: CODE SEMANTIC ANALYSIS
**Step 5.1 - Key data:** `frac_table_pixel[]` array only.
**Step 5.2 - Callers:** `clk_pixel_ops` (set via `.set_rate =
clk_pixel_set_rate` and `.determine_rate = clk_pixel_determine_rate`) is
used by 17+ Qualcomm dispcc drivers: SDM845, SM6350, SM7150, SM8250,
SM8450, SM8550, SM8750, X1E80100, SC7180, SC7280, SC8280XP, QCM2290,
SM4450, SM6375, SA8775P (dispcc0/1), etc. This is a HIGH IMPACT SURFACE
— affects display on almost every modern Qualcomm SoC.
**Step 5.3 - Callees:** Pure table lookup.
**Step 5.4 - Reachability:** Reached from `clk_set_rate()` on any MDSS
pixel clock → userspace-triggerable via normal display driver operations
(DRM probe, panel enable, mode set).
**Step 5.5 - Similar patterns:** The `b527358cb4cd5` commit is the exact
same pattern (add ratio to `frac_table_pixel`) and was backported to 8
stable trees.
## Phase 6: STABLE TREE ANALYSIS
**Step 6.1 - Code exists in stable:** Verified `frac_table_pixel[]` is
identical (`{3,8}, {2,9}, {4,9}, {1,1}, {2,3}`) on 5.10, 5.15, 6.1, 6.6,
6.12, 6.18, 6.19. Every active stable tree has the same buggy state.
**Step 6.2 - Backport complexity:** The `frac_table_pixel[]` array is in
the same place across all trees. Will apply cleanly or with trivial
context adjustment.
**Step 6.3 - Related fixes in stable:** `b527358cb4cd5` (adding `{2,3}`)
is in all stable trees. This new commit is the continuation.
## Phase 7: SUBSYSTEM CONTEXT
**Step 7.1 - Subsystem:** `drivers/clk/qcom/` - Qualcomm clock driver.
Level: IMPORTANT (affects many SoC families, any user with a Qualcomm
device using `clk_pixel_ops`).
**Step 7.2 - Activity:** Actively maintained subsystem; regular flow of
fixes.
## Phase 8: IMPACT & RISK
**Step 8.1 - Affected users:** Users of Qualcomm SoCs with DSI panels
requiring the specific pixel clock ratios — explicitly 10-bit DSI C-PHY
panels and other configurations where pclk/byteclk combinations force a
16:35 or 4:15 ratio.
**Step 8.2 - Trigger conditions:** Normal display operation with
affected panels. No special privileges needed (display usage is common).
**Step 8.3 - Failure mode severity:** HIGH — pixel clock is set to
completely wrong rate (e.g., 50 MHz instead of 173 MHz, a 3.4x error).
This causes visible display corruption / non-functional display on
affected hardware. Not a crash, but user-visible broken functionality
with no workaround.
**Step 8.4 - Risk/benefit:**
- Benefit: HIGH (fixes display for a class of panels across many SoCs)
- Risk: VERY LOW (2 lines of data, table iteration is in-order; existing
ratios still match first)
- Ratio: Strongly favors backport.
## Phase 9: SYNTHESIS
**Evidence FOR backporting:**
- Fixes real observed runtime failure with detailed clk_summary evidence
- Same pattern (adding ratio to `frac_table_pixel`) was previously
backported to 8 stable trees (`b527358cb4cd5` went to 4.9.y, 4.14.y,
4.19.y, 5.4.y, 5.10.y, 5.15.y, 5.16.y, 5.17.y)
- Minimal 2-line change in a const data table
- Zero functional risk (iteration is ordered; additions cannot break
existing cases)
- Reviewed by two subsystem experts + applied by Qualcomm SoC maintainer
- Falls into "hardware quirk/workaround" exception category (analogous
to device ID addition)
- Code exists identically in all active stable trees
- Used by 17+ SoC drivers → broad user impact
**Evidence AGAINST backporting:**
- No explicit Fixes: tag (though prior identical-pattern fix had one,
and absence of tag is explicitly not a signal per the guidelines)
- Commit message uses "expand" instead of "fix" (but body describes
concrete failure)
- No Cc: stable from the author
**Stable rules check:**
1. Obviously correct? YES — pure data addition
2. Fixes real bug? YES — pixel clock misprogrammed to ~3.4x wrong rate
3. Important? YES — broken display on affected hardware
4. Small and contained? YES — 2 lines in one file
5. No new features/APIs? YES — extends internal lookup table, not
exposed
6. Applies to stable? YES — verified identical state across stable trees
**Exception category:** Fits "hardware quirks/workarounds" — enables
specific hardware configurations (10-bit DSI C-PHY panels) that were
previously non-functional due to missing table entries, directly
analogous to adding PCI/USB device IDs or codec quirks.
## Verification
- [Phase 1] Parsed tags: two Reviewed-by from Qualcomm experts, Link to
lore, no Fixes:/Cc:stable (expected)
- [Phase 2] Diff analysis: 2-line const data addition to
`frac_table_pixel[]` before sentinel; no control-flow change
- [Phase 3] `git log -- drivers/clk/qcom/clk-rcg2.c` + `git show
b527358cb4cd5`: confirmed precedent commit adding `{2,3}` was accepted
with Fixes: tag
- [Phase 3] `git log --author="Pengyu Luo"`: confirmed author has
multiple legitimate DSI/Qualcomm fixes
- [Phase 4] `b4 dig -c 0f5c8f03d990f`: returned
`lore.kernel.org/all/20260321095029.2259489-1-mitltlatltl@gmail.com/`
- [Phase 4] `b4 dig -c 0f5c8f03d990f -a`: single v1, no revisions
- [Phase 4] Thread contents via mbox: Taniya Das, Dmitry Baryshkov
Reviewed-by; Konrad asked a non-blocking question; Bjorn applied with
"Applied, thanks!"; no NAKs; no stable discussion
- [Phase 5] `grep -rln "clk_pixel_ops" drivers/clk/qcom/`: 17+
dispcc/gcc drivers use the affected ops (SDM845, SM8250, SM8450,
SM8550, SM8750, X1E80100, SC7180, SC7280, SC8280XP, QCM2290, SM4450,
SM6350, SM6375, SM7150, SA8775P, etc.)
- [Phase 6] Examined `drivers/clk/qcom/clk-rcg2.c` at for-greg/5.10-200,
5.15-200, 6.1-200, 6.6-200, 6.12-200, 6.18-200, 6.19-200:
`frac_table_pixel[]` identical across all trees — will apply cleanly
- [Phase 6] `grep -rl "b527358cb4cd" /home/sasha/stable-
queue/releases/`: confirmed prior similar commit was backported to
4.9.311, 4.14.276, 4.19.238, 5.4.189, 5.10.110, 5.15.33, 5.16.19,
5.17.2
- [Phase 8] Failure mode from commit body: pclk set to 50455997 Hz
instead of 172992000 Hz (3.4x off) on 10-bit DSI C-PHY panels — user-
visible display failure
---
This is a well-reviewed, minimal hardware-enablement fix (analogous to a
hardware quirk) that addresses a documented, reproducible runtime
failure on real hardware. The fix is a 2-line data-table extension with
zero regression risk. There is strong precedent: a commit with the exact
same pattern (`b527358cb4cd5`) was backported broadly to stable. The
affected code is used by 17+ Qualcomm SoC drivers, giving wide user
impact.
**YES**
drivers/clk/qcom/clk-rcg2.c | 2 ++
1 file changed, 2 insertions(+)
diff --git a/drivers/clk/qcom/clk-rcg2.c b/drivers/clk/qcom/clk-rcg2.c
index fc696b66ccda9..6064a0e17d519 100644
--- a/drivers/clk/qcom/clk-rcg2.c
+++ b/drivers/clk/qcom/clk-rcg2.c
@@ -1117,6 +1117,8 @@ static const struct frac_entry frac_table_pixel[] = {
{ 4, 9 },
{ 1, 1 },
{ 2, 3 },
+ { 16, 35},
+ { 4, 15},
{ }
};
--
2.53.0
^ permalink raw reply related [flat|nested] 2+ messages in thread* [PATCH AUTOSEL 7.0-5.15] dt-bindings: clock: qcom,gcc-sc8180x: Add missing GDSCs
[not found] <20260428104133.2858589-1-sashal@kernel.org>
2026-04-28 10:41 ` [PATCH AUTOSEL 7.0-5.10] clk: qcom: rcg2: expand frac table for mdss_pixel_clk_src Sasha Levin
@ 2026-04-28 10:41 ` Sasha Levin
1 sibling, 0 replies; 2+ messages in thread
From: Sasha Levin @ 2026-04-28 10:41 UTC (permalink / raw)
To: patches, stable
Cc: Val Packett, Krzysztof Kozlowski, Bjorn Andersson, Sasha Levin,
agross, konrad.dybcio, mturquette, sboyd, robh+dt,
krzysztof.kozlowski+dt, conor+dt, linux-arm-msm, linux-clk,
devicetree, linux-kernel
From: Val Packett <val@packett.cool>
[ Upstream commit 76404ffbf07f28a5ec04748e18fce3dac2e78ef6 ]
There are 5 more GDSCs that we were ignoring and not putting to sleep,
which are listed in downstream DTS. Add them.
Signed-off-by: Val Packett <val@packett.cool>
Acked-by: Krzysztof Kozlowski <krzysztof.kozlowski@oss.qualcomm.com>
Link: https://lore.kernel.org/r/20260312112321.370983-2-val@packett.cool
Signed-off-by: Bjorn Andersson <andersson@kernel.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
LLM Generated explanations, may be completely bogus:
I have all the evidence I need. Now let me write my analysis.
## Phase 1: Commit Message Forensics
**Step 1.1: Parse subject line**
Record: Subsystem: `dt-bindings: clock: qcom,gcc-sc8180x`. Action verb:
"Add". Summary: Adds 5 missing GDSC (Global Distributed Switch
Controller) #defines to the binding header.
**Step 1.2: Parse all tags**
Record: Tags found: `Signed-off-by: Val Packett`, `Acked-by: Krzysztof
Kozlowski` (DT bindings maintainer), `Link:` to lore.kernel.org thread,
`Signed-off-by: Bjorn Andersson` (Qualcomm maintainer who applied). No
`Fixes:` tag on this bindings patch (but its companion driver patch
`3565741eb985a` has `Fixes: 4433594bbe5d`). No `Cc: stable` tag.
**Step 1.3: Analyze commit body**
Record: "There are 5 more GDSCs that we were ignoring and not putting to
sleep" — explicitly describes missing PM/power management support. The
commit adds 5 new #define identifiers (values 11-15) for MMNOC MMU TBU
(HF0/HF1/SF) and Turing MMU TBU0/TBU1 GDSCs. No version info mentioned.
Author's explanation: these were missing from mainline driver but
present in downstream DTS.
**Step 1.4: Detect hidden fix**
Record: Language uses "Add missing" — typical hidden-fix pattern. The
driver companion has `Fixes: 4433594bbe5d` tag pointing to the original
SC8180x driver (v5.12). This is a bug fix by nature (missing power
management), but THIS patch is only the header definitions.
## Phase 2: Diff Analysis
**Step 2.1: Inventory**
Record: Single file modified: `include/dt-bindings/clock/qcom,gcc-
sc8180x.h`. 5 lines added, 0 removed. Zero functions modified — purely
adding preprocessor macros.
**Step 2.2: Code flow change**
Record: Before: header defined GDSC IDs 0-10. After: header defines GDSC
IDs 0-15 (adds 11-15). No execution-path change; these are constants
used by other code (driver `drivers/clk/qcom/gcc-sc8180x.c` in the
companion patch) and potentially DTS files.
**Step 2.3: Bug mechanism category**
Record: Category (h) Hardware enablement — adds IDs needed to expose
hardware GDSCs. This is a prerequisite for the follow-on driver patch
that actually registers the 5 GDSCs so they can be power-managed.
**Step 2.4: Fix quality**
Record: Trivially correct — just #define additions. Zero regression risk
on its own (unused constants). Obvious correctness verifiable by reading
the names and numbering. No red flags.
## Phase 3: Git History Investigation
**Step 3.1: Blame**
Record: The file was introduced in commit 4433594bbe5d (SC8180x GCC
driver, v5.12-rc1, January 2021). The existing GDSC section (IDs 0-10)
has been stable since then. This patch only appends new IDs.
**Step 3.2: Fixes target**
Record: This bindings patch has no Fixes: tag. The driver companion
`3565741eb985a` has `Fixes: 4433594bbe5d` ("clk: qcom: gcc: Add global
clock controller driver for SC8180x"). That target commit is in v5.12
and every stable tree since (5.15, 6.1, 6.6, 6.12).
**Step 3.3: File history**
Record: Recent changes to the file have been small additions (GPLL9
support, USB MP resets, UFS QREF clocks) — standard "add missing"
completions. This fits the same pattern. Part of an 11-patch series
"clk: qcom: sc8180x: PM-related fixes (and refactoring)" but this
specific commit + the driver commit (patches 01/11 and 02/11) are the
only "fix missing GDSCs" pair.
**Step 3.4: Author context**
Record: Author Val Packett has submitted Qualcomm platform work
previously; the patch is Acked-by the DT binding maintainer (Krzysztof
Kozlowski) and applied by the Qualcomm SoC maintainer (Bjorn Andersson).
The driver commit got Reviewed-by from two additional Qualcomm
maintainers (Dmitry Baryshkov, Konrad Dybcio).
**Step 3.5: Dependencies**
Record: This bindings patch is a prerequisite for the driver patch
`3565741eb985a`, which references `HLOS1_VOTE_MMNOC_MMU_TBU_HF0_GDSC`
etc. Without this header change, the driver patch won't compile
(verified: `drivers/clk/qcom/gcc-sc8180x.c:17` includes this header).
## Phase 4: Mailing List Research
**Step 4.1: Original discussion**
Record: `b4 dig -c 76404ffbf07f2` found
https://patch.msgid.link/20260312112321.370983-2-val@packett.cool. Part
of v2 series (v1 had 7 patches, v2 expanded to 11 patches). Applied
version is v2. Thread saved; no stable nominations, no NAKs, no concerns
raised on this specific patch.
**Step 4.2: Reviewers**
Record: Acked-by Krzysztof Kozlowski (DT bindings maintainer). The
broader series was reviewed by subsystem maintainers Dmitry Baryshkov
and Konrad Dybcio.
**Step 4.3: Bug report search**
Record: No Reported-by tag, no bug link. The issue was identified by
comparing against downstream DTS.
**Step 4.4: Series context**
Record: 11-patch series. Patches 01-02 are the "add missing GDSCs" pair
(bindings + driver). Patches 03-06 are PM retention/runtime-PM
enablement (larger functional changes). Patches 07-08 are dispcc
changes, 09-11 are camcc refactoring. Only 01+02 are tight bug-fix
material.
**Step 4.5: Stable list**
Record: No stable-list discussion found about this specific patch.
## Phase 5: Code Semantic Analysis
**Step 5.1: Key symbols**
Record: 5 preprocessor constants:
HLOS1_VOTE_MMNOC_MMU_TBU_HF0/HF1/SF_GDSC and
HLOS1_VOTE_TURING_MMU_TBU0/1_GDSC. No functions modified.
**Step 5.2-5.4: Callers/callees**
Record: Used by `drivers/clk/qcom/gcc-sc8180x.c` to index into the
`gcc_sc8180x_gdscs[]` array (verified via grep). Not directly reachable
from user code; these IDs reference power domains managed by the clock
framework and consumed by SMMU/Turing subsystems on SC8180x hardware
(e.g. Microsoft Surface Pro X).
**Step 5.5: Similar patterns**
Record: **Strong precedent found**. An essentially identical SC8280XP
pair exists:
- `9eba4db02a88` (SC8280XP bindings: "Add missing GDSCs") +
`4712eb7ff85b` (SC8280XP driver fix)
- Both were backported to stable as `66120ba55999a` (explicitly labeled
`Stable-dep-of: 4712eb7ff85b`) and `a92a9604e8a43` respectively. The
SC8280XP commit message is almost verbatim identical, and the Qualcomm
stable process treated the bindings half as a required dependency.
## Phase 6: Cross-referencing / Stable Tree
**Step 6.1: Code in stable**
Record: The header file and driver exist in all stable trees ≥5.12. The
incomplete GDSC list is present in all active stable trees.
**Step 6.2: Backport cleanliness**
Record: Bindings file context from line 320-325 is unchanged since 2023
(last modification 19ac3579af14e "Add missing bindings on gcc-sc8180x").
The addition appends at end of GDSC section — should apply cleanly to
all stable trees without conflicts.
**Step 6.3: Related fixes in stable**
Record: SC8280XP equivalent already in stable (same fix pattern for
sibling SoC).
## Phase 7: Subsystem
**Step 7.1**: Record: `drivers/clk/qcom/` (via header it defines) and
`include/dt-bindings/` — Qualcomm clock/PM subsystem. Criticality:
PERIPHERAL (specific to SC8180x, used in Microsoft Surface Pro X-class
laptops and similar devices).
**Step 7.2**: Record: Qualcomm clock driver area is actively maintained;
this patch went through normal review cycle (v1→v2).
## Phase 8: Impact / Risk
**Step 8.1: Affected users**
Record: SC8180x platform users (notably Surface Pro X; ARM64 laptops).
When combined with driver patch, affects power consumption on these
devices.
**Step 8.2: Trigger**
Record: Always active — SMMU TBU / Turing TBU GDSCs remain powered-on
because kernel doesn't vote them off.
**Step 8.3: Severity of this patch alone**
Record: This bindings-only patch has ZERO runtime effect by itself.
Severity of the **combined fix** (with companion driver patch): MEDIUM —
power waste, excess heat, degraded battery. Not a crash, not a
corruption, but real user-facing PM issue.
**Step 8.4: Risk-benefit**
Record: Benefit: enables the companion driver fix to apply and build.
Risk: essentially zero (5 unused preprocessor macros if driver patch not
applied). As Stable-dep-of — safe and necessary.
## Phase 9: Synthesis
**Evidence FOR:**
- Companion driver fix has `Fixes: 4433594bbe5d` pointing to v5.12;
valid bug fix
- Strong, nearly identical precedent: SC8280XP pair was backported to
stable exactly this way (Stable-dep-of marker)
- Five trivial macro additions; zero regression risk
- Applies cleanly to all stable trees (no conflicts in the appended
section)
- Acked by DT bindings maintainer, reviewed by Qualcomm maintainers
- Required prerequisite — without it the driver fix will not compile in
stable
**Evidence AGAINST:**
- This patch alone has no runtime effect; it's a dependency, not a
standalone fix
- The underlying issue is "missing PM" not "crash/corruption"
- Part of a larger 11-patch series, most of which is NOT stable material
**Stable rules check:**
1. Obviously correct — yes (5 #define lines)
2. Fixes real bug — yes, when paired with driver patch (power waste)
3. Important issue — borderline: PM/power waste, not crash
4. Small & contained — yes (5 lines, 1 file)
5. No new features/APIs — yes (enables existing hardware features
already in DT bindings header)
6. Applies to stable — yes (verified file structure unchanged)
**Exception category**: This is effectively a DT binding additions for
existing hardware (exception category 3) AND a required Stable-dep-of
for a Fixes:-tagged driver commit — which was the exact rationale used
for the SC8280XP precedent.
## Verification
- [Phase 1] Parsed tags via `git show 76404ffbf07f2`: Acked-by Krzysztof
Kozlowski, Signed-off-by Bjorn Andersson, Link to lore. No
Fixes:/stable tags on bindings commit.
- [Phase 1] Companion `git show 3565741eb985a` confirmed `Fixes:
4433594bbe5d` and two Reviewed-by tags.
- [Phase 2] Diff analysis: 5 line additions in one file, pure #define
macros.
- [Phase 3] `git show 4433594bbe5d` and `git describe --contains
4433594bbe5d` → v5.12-rc1~110^2^4~33. Bug present since v5.12.
- [Phase 3] `git log --oneline -- include/dt-bindings/clock/qcom,gcc-
sc8180x.h`: confirms file has been amended via "Add missing X" commits
repeatedly.
- [Phase 4] `b4 dig -c 76404ffbf07f2`: found
https://patch.msgid.link/20260312112321.370983-2-val@packett.cool
- [Phase 4] `b4 dig -c 76404ffbf07f2 -a`: found v1 (7-patch) and v2
(11-patch). Applied = v2 (latest).
- [Phase 4] Thread saved and searched for "stable": no stable
nominations or objections.
- [Phase 5] `grep qcom,gcc-sc8180x.h drivers/clk/qcom/gcc-sc8180x.c`:
confirms line 17 includes this header — driver build depends on these
defines.
- [Phase 5] `git show 3565741eb985a | grep HLOS1_VOTE_`: driver patch
uses all 5 new defines.
- [Phase 5] Precedent: `git show 66120ba55999a`: confirmed "[ Upstream
commit 9eba4db02a88e7a810aabd70f7a6960f184f391f ]" and "Stable-dep-of:
4712eb7ff85b" — identical pattern backported to stable for SC8280XP.
- [Phase 5] `git show a92a9604e8a43`: confirmed companion SC8280XP
driver fix was also backported.
- [Phase 6] `git describe --contains 9eba4db02a88` → v6.6-rc1. Stable
backports landed in older branches with Stable-dep-of marker.
- [Phase 6] Read current file (lines 300-327): confirmed GDSC section
ends at USB30_SEC_GDSC=10; appending 5 new IDs won't conflict with any
downstream state in stable.
- UNVERIFIED: Could not fetch the actual lore thread content (anti-bot
wall); relied on saved mbox and local commit metadata. Could not
verify stable maintainer's intention for this specific pair, but
SC8280XP precedent is unambiguous.
## Conclusion
This is a pure DT-bindings header addition that is safe on its own (zero
runtime impact) and is a **required prerequisite** for the companion
driver patch `3565741eb985a` which has a `Fixes:` tag pointing to v5.12.
The almost identical SC8280XP bindings commit (`9eba4db02a88`) was
backported to stable as `Stable-dep-of: 4712eb7ff85b`, establishing a
clear precedent. Without this patch, the driver fix cannot compile in
stable trees. It is small, obviously correct, applies cleanly, and
follows an exception category (DT bindings for existing hardware +
required dependency for a Fixes:-tagged fix).
**YES**
include/dt-bindings/clock/qcom,gcc-sc8180x.h | 5 +++++
1 file changed, 5 insertions(+)
diff --git a/include/dt-bindings/clock/qcom,gcc-sc8180x.h b/include/dt-bindings/clock/qcom,gcc-sc8180x.h
index b9d8438a15ffb..9ed7b794aacc4 100644
--- a/include/dt-bindings/clock/qcom,gcc-sc8180x.h
+++ b/include/dt-bindings/clock/qcom,gcc-sc8180x.h
@@ -322,5 +322,10 @@
#define USB30_MP_GDSC 8
#define USB30_PRIM_GDSC 9
#define USB30_SEC_GDSC 10
+#define HLOS1_VOTE_MMNOC_MMU_TBU_HF0_GDSC 11
+#define HLOS1_VOTE_MMNOC_MMU_TBU_HF1_GDSC 12
+#define HLOS1_VOTE_MMNOC_MMU_TBU_SF_GDSC 13
+#define HLOS1_VOTE_TURING_MMU_TBU0_GDSC 14
+#define HLOS1_VOTE_TURING_MMU_TBU1_GDSC 15
#endif
--
2.53.0
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