[v3,0/3] PCI: brcmstb: Configure appropriate HW CLKREQ# mode

Message

Jim Quinlan April 19, 2023, 4:57 p.m. UTC

Note: (a) With this series, all downstream devices should work w/o DT changes.
          Only if the user desires L1SS savings and has an L1SS-capable
          device is a DT change required (brcm,enable-l1ss).
      (b) No code changes between V2->V3 except to remove a dev_info()
          and change the string of another dev_info().

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 (3):
  dt-bindings: PCI: brcmstb: brcm,{enable-l1ss,completion-timeout-us}
    props
  PCI: brcmstb: Configure HW CLKREQ# mode appropriate for downstream
    device
  PCI: brcmstb: Set PCIe transaction completion timeout

 .../bindings/pci/brcm,stb-pcie.yaml           | 16 +++
 drivers/pci/controller/pcie-brcmstb.c         | 99 +++++++++++++++++--
 2 files changed, 105 insertions(+), 10 deletions(-)


base-commit: 76f598ba7d8e2bfb4855b5298caedd5af0c374a8
prerequisite-patch-id: f38de8681d8746126d60b3430eaf218d2dd169cd
prerequisite-patch-id: 23e13189f200358976abf5bf3600973a20cf386c
prerequisite-patch-id: edfbe6ea39ed6a4937e2cec3bb8ee0e60091546d
prerequisite-patch-id: c87dd155e8506a2a277726c47d85bf3fa83727d5
prerequisite-patch-id: 579841e1dc179517506a7a7c42e0e651b3bc3649
prerequisite-patch-id: b5b079998ea451821edffd7c52cd3d89d06046a1
prerequisite-patch-id: b51b3918e554e279b2ace1f68ed6b4176f8ccc24
prerequisite-patch-id: 333e5188fb27d0ed010f5359e83e539172a67690
prerequisite-patch-id: bb107ee7b4811a9719508ea667cad2466933dec0