Hi!

On 2016-03-03 23:27, Peter Rosin wrote:

From: Peter Rosin <redacted>

Hi!

I have a pair of boards with this i2c topology:

                       GPIO ---|  ------ BAT1
                        |      v /
   I2C  -----+------B---+---- MUX
             |                   \
           EEPROM                 ------ BAT2

	(B denotes the boundary between the boards)

The problem with this is that the GPIO controller sits on the same i2c bus
that it MUXes. For pca954x devices this is worked around by using unlocked
transfers when updating the MUX. I have no such luck as the GPIO is a general
purpose IO expander and the MUX is just a random bidirectional MUX, unaware
of the fact that it is muxing an i2c bus. Extending unlocked transfers
into the GPIO subsystem is too ugly to even think about. But the general hw
approach is sane in my opinion, with the number of connections between the
two boards minimized. To put is plainly, I need support for it.

etc etc

I've made a few changes, but instead of posting another copy of a rather long
series, I decided to push it to github and only post a note about it here. The
plan is to then rebase (if needed) on top of v4.6-rc1 and at that point post
all the patches (this is, after all, at least 4.7 material). At the same time
I do not want to hide the latest version from anyone wanting to have a look or
test.

The series will be posted again for review. This is just a heads up.

v5 compared to v4:
- Rebase on top of v4.5-rc7.
- A new patch making me maintainer of i2c muxes (also sent separately).
- A new file Documentation/i2c/i2c-topology that describes various muxing
  issues.
- Rename "i2c-controlled" muxes "self-locked" instead, as it is perfectly
  reasonable to have i2c-controlled muxes that use the pre-existing locking
  scheme. The pre-existing locking scheme for i2c muxes is from here on
  called "parent-locked".
- Rename i2c-mux.c:i2c_mux_master_xfer to __i2c_mux_master_xfer since it
  calls __i2c_transfer, which leaves room for a new i2c_mux_master_xfer
  that calls i2c_transfer. Similar rename shuffle for i2c_mux_smbus_xfer.
- Use sizeof(*priv) instead of sizeof(struct i2c_mux_priv). One instance.
- Some follow-up patches that were posted in response to v2-v4 cleaning up
  and simplifying various i2c muxes outside drivers/i2c/, among those is
  an unrelated cleanup patch to drivers/media/dvb-frontends/rtl2832.c that
  I carry here since it conflicts (trivially) with this series. That
  unrelated patch is (currently) the last patch in the series.


The series looks like this now:

The following changes since commit f6cede5b49e822ebc41a099fe41ab4989f64e2cb:

  Linux 4.5-rc7 (2016-03-06 14:48:03 -0800)

are available in the git repository at:

  https://github.com/peda-r/i2c-mux.git mux-core-and-locking-5

for you to fetch changes up to c1ef4a249b0bd45ba97e14f15f6ee89e7fbc0222:

  [media] rtl2832: regmap is aware of lockdep, drop local locking hack (2016-03-15 10:02:15 +0100)

----------------------------------------------------------------
Antti Palosaari (1):
      [media] si2168: declare that the i2c gate is self-locked

Peter Rosin (24):
      MAINTAINERS: add myself as i2c mux maintainer
      i2c-mux: add common data for every i2c-mux instance
      i2c: i2c-mux-gpio: convert to use an explicit i2c mux core
      i2c: i2c-mux-pinctrl: convert to use an explicit i2c mux core
      i2c: i2c-arb-gpio-challenge: convert to use an explicit i2c mux core
      i2c: i2c-mux-pca9541: convert to use an explicit i2c mux core
      i2c: i2c-mux-pca954x: convert to use an explicit i2c mux core
      i2c: i2c-mux-reg: convert to use an explicit i2c mux core
      iio: imu: inv_mpu6050: convert to use an explicit i2c mux core
      [media] m88ds3103: convert to use an explicit i2c mux core
      [media] rtl2830: convert to use an explicit i2c mux core
      [media] rtl2832: convert to use an explicit i2c mux core
      [media] si2168: convert to use an explicit i2c mux core
      [media] cx231xx: convert to use an explicit i2c mux core
      of/unittest: convert to use an explicit i2c mux core
      i2c-mux: drop old unused i2c-mux api
      i2c: allow adapter drivers to override the adapter locking
      i2c: muxes always lock the parent adapter
      i2c-mux: relax locking of the top i2c adapter during self-locked muxing
      i2c-mux: document i2c muxes and elaborate on parent-/self-locked muxes
      iio: imu: inv_mpu6050: declare that the i2c gate is self-locked
      [media] rtl2832: declare that the i2c gate is self-locked
      [media] rtl2832_sdr: get rid of empty regmap wrappers
      [media] rtl2832: regmap is aware of lockdep, drop local locking hack

 Documentation/i2c/i2c-topology               | 312 ++++++++++++++++++++++++
 MAINTAINERS                                  |  11 +
 drivers/i2c/i2c-core.c                       |  65 +++--
 drivers/i2c/i2c-mux.c                        | 347 ++++++++++++++++++++++-----
 drivers/i2c/muxes/i2c-arb-gpio-challenge.c   |  47 ++--
 drivers/i2c/muxes/i2c-mux-gpio.c             |  72 +++---
 drivers/i2c/muxes/i2c-mux-pca9541.c          |  55 ++---
 drivers/i2c/muxes/i2c-mux-pca954x.c          |  64 ++---
 drivers/i2c/muxes/i2c-mux-pinctrl.c          | 124 +++++-----
 drivers/i2c/muxes/i2c-mux-reg.c              |  63 ++---
 drivers/iio/imu/inv_mpu6050/inv_mpu_acpi.c   |   2 +-
 drivers/iio/imu/inv_mpu6050/inv_mpu_core.c   |  75 ++----
 drivers/iio/imu/inv_mpu6050/inv_mpu_iio.h    |   3 +-
 drivers/media/dvb-frontends/m88ds3103.c      |  18 +-
 drivers/media/dvb-frontends/m88ds3103_priv.h |   2 +-
 drivers/media/dvb-frontends/rtl2830.c        |  17 +-
 drivers/media/dvb-frontends/rtl2830_priv.h   |   2 +-
 drivers/media/dvb-frontends/rtl2832.c        | 236 +++---------------
 drivers/media/dvb-frontends/rtl2832.h        |   4 +-
 drivers/media/dvb-frontends/rtl2832_priv.h   |   3 +-
 drivers/media/dvb-frontends/rtl2832_sdr.c    | 303 ++++++++++-------------
 drivers/media/dvb-frontends/rtl2832_sdr.h    |   5 +-
 drivers/media/dvb-frontends/si2168.c         |  82 ++-----
 drivers/media/dvb-frontends/si2168_priv.h    |   2 +-
 drivers/media/usb/cx231xx/cx231xx-core.c     |   6 +-
 drivers/media/usb/cx231xx/cx231xx-i2c.c      |  47 ++--
 drivers/media/usb/cx231xx/cx231xx.h          |   4 +-
 drivers/media/usb/dvb-usb-v2/rtl28xxu.c      |   5 +-
 drivers/of/unittest.c                        |  40 ++-
 include/linux/i2c-mux.h                      |  65 ++++-
 include/linux/i2c.h                          |  28 ++-
 31 files changed, 1206 insertions(+), 903 deletions(-)
 create mode 100644 Documentation/i2c/i2c-topology