[PATCH v8 0/2] PCI: brcmstb: Configure appropriate HW CLKREQ# mode

[Jim Quinlan]

V8 -- Un-advertise L1SS capability when in "no-l1ss" mode (Bjorn)
   -- Squashed last two commits of v7 (Bjorn)
   -- Fix DT binding description text wrapping (Bjorn)
   -- Fix incorrect Spec reference (Bjorn)
         s/PCIe Spec/PCIe Express Mini CEM 2.1 specification/
   -- Text substitutions (Bjorn)
         s/WRT/With respect to/ 
         s/Tclron/T_CLRon/

v7 -- Manivannan Sadhasivam suggested (a) making the property look like a
      network phy-mode and (b) keeping the code simple (not counting clkreq
      signal appearances, un-advertising capabilites, etc).  This is
      what I have done.  The property is now "brcm,clkreq-mode" and
      the values may be one of "safe", "default", and "no-l1ss".  The
      default setting is to employ the most capable power savings mode.

v6 -- No code has been changed.
   -- Changed commit subject and comment in "#PERST" commit (Bjorn, Cyril)
   -- Changed sign-off and author email address for all commits.
      This was due to a change in Broadcom's upstreaming policy.

v5 -- Remove DT property "brcm,completion-timeout-us" from	 
      "DT bindings" commit.  Although this error may be reported	 
      as a completion timeout, its cause was traced to an	 
      internal bus timeout which may occur even when there is	 
      no PCIe access being processed.  We set a timeout of four	 
      seconds only if we are operating in "L1SS CLKREQ#" mode.
   -- Correct CEM 2.0 reference provided by HW engineer,
      s/3.2.5.2.5/3.2.5.2.2/ (Bjorn)
   -- Add newline to dev_info() string (Stefan)
   -- Change variable rval to unsigned (Stefan)
   -- s/implementaion/implementation/ (Bjorn)
   -- s/superpowersave/powersupersave/ (Bjorn)
   -- Slightly modify message on "PERST#" commit.
   -- Rebase to torvalds master

v4 -- New commit that asserts PERST# for 2711/RPi SOCs at PCIe RC
      driver probe() time.  This is done in Raspian Linux and its
      absence may be the cause of a failing test case.
   -- New commit that removes stale comment.

v3 -- Rewrote commit msgs and comments refering panics if L1SS
      is enabled/disabled; the code snippet that unadvertises L1SS
      eliminates the panic scenario. (Bjorn)
   -- Add reference for "400ns of CLKREQ# assertion" blurb (Bjorn)
   -- Put binding names in DT commit Subject (Bjorn)
   -- Add a verb to a commit's subject line (Bjorn)
   -- s/accomodat(\w+)/accommodat$1/g (Bjorn)
   -- Rewrote commit msgs and comments refering panics if L1SS
      is enabled/disabled; the code snippet that unadvertises L1SS
      eliminates the panic scenario. (Bjorn)

v2 -- Changed binding property 'brcm,completion-timeout-msec' to
      'brcm,completion-timeout-us'.  (StefanW for standard suffix).
   -- Warn when clamping timeout value, and include clamped
      region in message. Also add min and max in YAML. (StefanW)
   -- Qualify description of "brcm,completion-timeout-us" so that
      it refers to PCIe transactions. (StefanW)
   -- Remvove mention of Linux specifics in binding description. (StefanW)
   -- s/clkreq#/CLKREQ#/g (Bjorn)
   -- Refactor completion-timeout-us code to compare max and min to
      value given by the property (as opposed to the computed value).

v1 -- The current driver assumes the downstream devices can
      provide CLKREQ# for ASPM.  These commits accomodate devices
      w/ or w/o clkreq# and also handle L1SS-capable devices.

   -- The Raspian Linux folks have already been using a PCIe RC
      property "brcm,enable-l1ss".  These commits use the same
      property, in a backward-compatible manner, and the implementaion
      adds more detail and also automatically identifies devices w/o
      a clkreq# signal, i.e. most devices plugged into an RPi CM4
      IO board.

Jim Quinlan (2):
  dt-bindings: PCI: brcmstb: Add property "brcm,clkreq-mode"
  PCI: brcmstb: Configure HW CLKREQ# mode appropriate for downstream
    device

 .../bindings/pci/brcm,stb-pcie.yaml           | 18 ++++
 drivers/pci/controller/pcie-brcmstb.c         | 96 +++++++++++++++++--
 2 files changed, 104 insertions(+), 10 deletions(-)


base-commit: 305230142ae0637213bf6e04f6d9f10bbcb74af8
-- 
2.17.1

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