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[Kleber Sacilotto de Souza <kleber.souza@xxxxxxxxxxxxx>]

** Also affects: linux-raspi2 (Ubuntu Xenial)
   Importance: Undecided
       Status: New

** Changed in: linux-raspi2 (Ubuntu Xenial)
       Status: New => In Progress

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https://bugs.launchpad.net/bugs/1784025

Title:
  Support for the RaspberryPi 3 B Plus board

Status in linux-raspi2 package in Ubuntu:
  Confirmed
Status in linux-raspi2 source package in Xenial:
  In Progress

Bug description:
  Impact:

  The RaspberryPi 3 B Plus[1] is the latest addition in the family of
  RaspberryPi boards, and this patchset includes all the necessary bits
  (dts, lan driver and wifi driver) to enable this board in our 4.4
  Xenial raspi2 kernel.

  How to test:

  Build this kernel and boot a rpi3bplus with it: the board should boot
  fine, and ethernet lan and wifi should work.

  Regression potential:

  To ease the regression analysis, we can logically split the patchset
  in 3 different set of patches.

  1) the dts files (patches 0001 to 0006)

  Patch 0001 contains the pi3bplus board dts files + the lan dts fragment - these are new files, and don't modify any other dts in the tree.
  Patches 0002 to 0005 are the fixup modifcation to make the above dts file work in our 4.4 kernel.
  Patch 006 is a fix for the bcm2708_common, a device tree used in every rpi board dtb - it's a small fix, and the same modification is present in the 4.9+ Raspberry respository too (see https://github.com/raspberrypi/linux/blob/rpi-4.9.y/arch/arm/boot/dts/bcm283x.dtsi aroud lines 353-354) - unfortunately they squashed that fix, so i couldn't pick the specific commit.

  The only regression potential here is patch 0006, but since it's a
  small fix, and it's even carried upstream, i mark it as low.

  2) the lan driver (patches 0008 to 0018)

  The rpi3bplus comes with a brand new gigabit capable ethernet adapter,
  driven by the lan 7515 chip, a chip mainly used in usb to ethernet
  dongle. Unfortunately, the lan7515 driver shipped in our Xenial tree
  was not working: the driver would attach, the interface shows up,
  packets could be sent, but the host os never received any input
  packets - sniffing the cable confirmed that the chip was generating
  traffic and receiving reply packets too.

  After some debugging i found that no interrupt was generated once
  packet arrived, and that was due to upstream
  23374573a899528a4b10d76276646f69b7ae1572 "lan78xx: Correctly indicate
  invalid OTP", reverting this would bring my ethernet back to life
  (patch 0008).

  "lan78xx: Correctly indicate invalid OTP" originated around 4.17, way
  after a complete overhaul of the phy code wad done for all the usbnet
  driver - after more debugging i found that the 4.4 driver ships a
  workaround to enable phy interrupts (see lan78xx_open()), so i'm
  thinking there's some correlation between the phy overhaul and this
  commit, but without the datasheet i can't tell what those bits in that
  register are actually doing - for now i just reverted this patch
  locally and made the driver work again.

  All the other patches (0009 to 0018) are backports of features added
  to the driver by the Raspberry Foundation to make the driver better
  integrate in a dts environment.

  There's literally no regression potential here, since the driver was
  not working in the first place, (and i actually made it work again).

  3) the wifi driver (patches 0019 to 0026)

  The wifi chip used in the rpi3bplus is very different from the one
  used in the original rpi3 board (Broadcom BCM43438 vs Cypress
  CYW43455), but it uses the same driver and i had to backport several
  fixes from upstream to make it work: all the commits fix isolated
  bugs, and can be easily reviewed.

  There's some regression potential here, but all code comes from
  upstream fixes, so i mark it as low.

  When possible i picked up the upstream version of the same patch
  (instead of the one carried in the RaspberryPi branch -
  https://github.com/raspberrypi/linux rpi-4.9.y), and except for these
  6 commits:

  "BCM270X_DT: Add Pi 3+ dts files"
  "lan78xx: Enable LEDs if no valid EEPROM or OTP"
  "lan78xx: Read initial EEE status from DT"
  "lan78xx: Change LEDs to include 10Mb activity"
  "lan78xx: Ignore DT MAC address if already valid"
  "lan78xx: Move enabling of EEE into PHY init code"

  all the remaining patches (20 out of 26) came from upstream - patches marked with 'cherry-picked...' are clean cherry picks, while the one with
  'backported...' required a varying degree of rework to make it apply (and work).

  I'm proposing this for inclusion in the Xenial raspi2 kernel.

  1: https://www.raspberrypi.org/blog/raspberry-pi-3-model-bplus-sale-
  now-35/

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