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Date: Tue, 15 Mar 2016 15:09:50 +0100
From: Peter Rosin <peda@...ator.liu.se>
To: linux-kernel@...r.kernel.org
CC: Peter Rosin <peda@...ntia.se>, Wolfram Sang <wsa@...-dreams.de>,
Peter Korsgaard <peter.korsgaard@...co.com>,
Guenter Roeck <linux@...ck-us.net>,
Jonathan Cameron <jic23@...nel.org>,
Hartmut Knaack <knaack.h@....de>,
Lars-Peter Clausen <lars@...afoo.de>,
Peter Meerwald <pmeerw@...erw.net>,
Antti Palosaari <crope@....fi>,
Mauro Carvalho Chehab <mchehab@....samsung.com>,
Rob Herring <robh+dt@...nel.org>,
Frank Rowand <frowand.list@...il.com>,
Grant Likely <grant.likely@...aro.org>,
Adriana Reus <adriana.reus@...el.com>,
Viorel Suman <viorel.suman@...el.com>,
Krzysztof Kozlowski <k.kozlowski@...sung.com>,
Terry Heo <terryheo@...gle.com>,
Hans Verkuil <hans.verkuil@...co.com>,
Arnd Bergmann <arnd@...db.de>,
Tommi Rantala <tt.rantala@...il.com>,
linux-i2c@...r.kernel.org, linux-iio@...r.kernel.org,
linux-media@...r.kernel.org, devicetree@...r.kernel.org
Subject: Re: [PATCH v4 00/18] i2c mux cleanup and locking update
Hi!
On 2016-03-03 23:27, Peter Rosin wrote:
> From: Peter Rosin <peda@...ntia.se>
>
> 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
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