[PATCH v10 0/7] PCI: brcmstb: root port turns on sub-device power

Jim Quinlan
2021-12-09T21:14:15Z

v10 -- Bindings commit example: in comment, refer to bridge under
controller node as a root port. (Pali)
-- Bindings commit example: remove three properties that are not
appropriate for a PCIe endpoint node. (Rob)

v9 -- Simplify where this mechanism works: instead of looking for
regulators below every bridge, just look for them at the
bridge under the root bus (root port). Now there is no
modification of portdrv_{pci,core}.c in this submission.
-- Although Pali is working on support for probing native
PCIe controller drivers, this work may take some time to
implement and it still might not be able to accomodate
our driver's requirements (e.g. vreg suspend/resume control).
-- Move regulator suspend/resume control to Brcm RC driver. It
must reside there because (a) in order to know when to
initiate linkup during resume and (b) to turn on the
regulators before any config-space accesses occur.
-- Commit message spelling, word choice (Bjorn, Krzysztof)
-- Refactor a small commit that was ignoring a funcs' return
values (Bjorn).
-- Here is a summary of this mechanism:

If:
-- PCIe RC driver sets pci_ops {add,remove)_bus to
pci_subdev_regulators_{add,remove}_bus during its probe.
-- There is a DT node "RB" under the host bridge DT node.
-- During the RC driver's pci_host_probe() the add_bus callback
is invoked where (bus->parent && pci_is_root_bus(bus->parent)
is true

Then:
-- A struct subdev_regulators structure will be allocated and
assigned to bus->dev.driver_data.
-- regulator_bulk_{get,enable}() will be invoked on &bus->dev
and the former will search for and process any
vpcie{12v,3v3,3v3aux}-supply properties that reside in node "RB".
-- The regulators will be turned off/on for any unbind/bind operations.
-- The regulators will be turned off/on for any suspend/resumes, but
only if the RC driver handles this on its own. This will appear
in a later commit for the pcie-brcmstb.c driver.

v8 -- Only the two binding commits and the "Change brcm_phy_stop()" commit
are unchanged.
-- The code has been moved to portdrv_pci.c and bus.c. The regulators
are placed in bus->dev.driver_data (bus->sysdata is already occupied
by the Broadcom PCIe). Two functions, pci_subdev_regulators_{add,remove}_bus()
are created to turn the regulators on/off. The pcie_portdriver also sets
its pci_driver methods suspend and resume when the conditions are
right for this feature. (Robh for suggestions, although I probably
erred in following them).
-- Have the root complex return 0xffffffff on accesses even when
the link is down and the HW doesn't support such accesses (PaliR).
-- Just call devm_bulk_regulator_get() on standard supplies; don't
bother pre-scanning the DT for them (MarkB).

v7 -- RobH suggested putting the "vpcixxx-supply" property under the
bridge-node rather than the endpoint device node. Also, he said to
use the pci-ops add_bus/remove methods. Doing so simplifies the
code greatly and three commits were dropped. Thanks!

-- Rob also suggested (I think) having this patchset be a general
feature which is activated by an OF property under the bridge node.
I tried to do that but realized that our root complex driver
controls the regulators with its dev_pm_ops and there is no way to
transfer this control when using general mechanism. Note that
although the regulator core deals with suspend, our RC driver wants
the right to sometimes to preclude this for WOL scenarios.

-- One commit was added to change the response to the return value of
the pci_ops add_bus() method. Currently, an error causes a WARNING,
a dev_err(...), and continues to return the child bus. The
modification was, for returning -ENOLINK only, to skip WARNING &
dev_err() and return NULL. This is necessary for our RC HW, as if
the code continues on it will do a pci_read_config_dword() for the
vendor/id, and our HW flags a CPU abort (instead of returning
0xffffffff) when the is no pcie-link established.

[NOTE: MarkB, I did not add one of your two "Reviewed-by"s
because the commit had a decent amount of change.]

v6 -- Dropped the idea of a placeholder regulator
property (brcm-ep-a-supply). (MarkB)
-- device_initialize() now called once. Two
commits were added for this. (GKH)
-- In two cases, separated a single function
into two or more functions (MarkB)
-- "(void)foo();" => "foo()". Note that although
foo() returns an int, in this instance it is being
invoked within a function returning void, and foo()
already executes a dev_err() on error. (MarkB)
-- Added a commit to correct PCIe interrupts in YAML.
-- Removed "device_type = "pci";" for the EP node
in the YAML example.
-- Updated the URL related to the voltage regulator
names on GitHub. Note that I added vpciev3v3aux.

v5 [NOTE: It has been a while since v4. Sorry]
-- See "PCI: allow for callback to prepare nascent subdev"
commit message for the cornerstone of this patchset
and the reasons behind it. This is a new commit.
-- The RC driver now looks into its DT children and
turns on regulators for a sub-device, and this occurs
prior to PCIe link as it must.
-- Dropped commits not related to the focus of this patchset.

v4 [NOTE: I'm not sure this fixes RobH and MarkB constraints but I'd
like to use this pullreq as a basis for future discussion.]
[Commit: Add bindings for ...]
-- Fix syntax error in YAML bindings example (RobH)
-- {vpcie12v,vpcie3v3}-supply props are back in root complex DT node
(I believe RobH said this was okay)
[Commit: Add control of ..]
-- Do not do global search for regulator; now we look specifically
for the property {vpcie12v,vpcie3v3}-supply in the root complex
DT node and then call devm_regulator_bulk_get() (MarkB)
-- Use devm_regulator_bulk_get() (Bjorn)
-- s/EP/slot0 device/ (Bjorn)
-- Spelling, capitalization (Bjorn)
-- Have brcm_phy_stop() return a void (Bjorn)
[Commit: Do not turn off ...]
-- Capitalization (Bjorn)
[Commit: Check return value ...]
-- Commit message content (Bjorn)
-- Move 6/6 hunk to 2/6 where it belongs (Bjorn)
-- Move the rest of 6/6 before all other commits (Bjorn)

v3 -- Driver now searches for EP DT subnode for any regulators to turn on.
If present, these regulators have the property names
"vpcie12v-supply" and "vpcie3v3-supply". The existence of these
regulators in the EP subnode are currently pending as a pullreq
in pci-bus.yaml at
https://github.com/devicetree-org/dt-schema/pull/54
(MarkB, RobH).
-- Check return of brcm_set_regulators() (Florian)
-- Specify one regulator string per line for easier update (Florian)
-- Author/Committer/Signoff email changed from that of V2 from
'james.quinlan@broadcom.com' to 'jim2101024@gmail.com'.

v2 -- Use regulator bulk API rather than multiple calls (MarkB).

v1 -- Bindings are added for fixed regulators that may power the EP device.
-- The brcmstb RC driver is modified to control these regulators
during probe, suspend, and resume.
-- 7216 type SOCs have additional error reporting HW and a
panic handler is added to dump its info.
-- A missing return value check is added.

Jim Quinlan (7):
PCI: brcmstb: Fix function return value handling
dt-bindings: PCI: Correct brcmstb interrupts, interrupt-map.
dt-bindings: PCI: Add bindings for Brcmstb EP voltage regulators
PCI: Add mechanism to turn on subdev regulators
PCI: brcmstb: Split brcm_pcie_setup() into two funcs
PCI: brcmstb: Add control of subdevice voltage regulators
PCI: brcmstb: Do not turn off WOL regulators on suspend

.../bindings/pci/brcm,stb-pcie.yaml | 31 ++-
drivers/pci/bus.c | 67 ++++++
drivers/pci/controller/pcie-brcmstb.c | 209 +++++++++++++++---
drivers/pci/pci.h | 8 +
4 files changed, 277 insertions(+), 38 deletions(-)

base-commit: ee1703cda8dc777e937dec172da55beaf1a74919
prerequisite-patch-id: 0905430e81a95900a1366916fe2940b848317a7c
prerequisite-patch-id: 710896210c50354d87f6025fe0bd1b89981138eb
prerequisite-patch-id: 97d3886cb911cb12ef3d514fdfff2a0ab11e8570
prerequisite-patch-id: 241f1e1878fc177d941f4982ca12779a29feb62b
prerequisite-patch-id: d856608825e2294297db5d7f88f8c180f3e5a1f2
prerequisite-patch-id: 92bcbc9772fb4d248157bcf35e799ac37be8ee45
prerequisite-patch-id: 6f4b1aac459bb54523ade0e87c04e9d6c45bd9f5
prerequisite-patch-id: 090ee7a3112a4ecb03805b23ed10e2c96b3b34ed
--
2.17.1