On Wed, Apr 03, 2019 at 02:40:07PM +0200, Wolfram Sang wrote: > This series adds support for very late atomic transfers to the I2C subsystem. > It finally reached a state which I think is ready-to-apply. This is mainly > because of two things: > > a) we decided to respect the current locking scheme and to not give atomic > transfers a priority. The code needed for that would have been either > incomplete or very invasive. And we cannot guarantee successful transfers > anyhow. See [1] for the discussion and other write-ups for design choices. > > b) thanks to a discussion with Peter Zijlstra[2], the conditions when to allow > atomic transfers became much clearer. The new helper i2c_in_atomic_xfer_mode() > adds readability, too. > > In detail, changes since RFC v2: > > * dropped coding style patch because already applied > * added new patch 1 to drop in_atomic() and have better conditions when > to enter the atomic path > * added support to the mux-core > * simplified omap conversion a little > * added new conversions for ocores, stu300, and algo-bit/gpio > * typo corrections found by Simon and Stefan > * added tags to drivers > * dropped tags from core patches because that part changed too much > > All tested on a Renesas Lager board (R-Car H2). Sadly, the i2c-sh_mobile driver > cannot be converted now because of other work needed first. I tested with the > i2c-gpio driver, though. The other driver patches are build tested. A branch > can be found here: > > git://git.kernel.org/pub/scm/linux/kernel/git/wsa/linux.git renesas/i2c/atomic_xfer > > I am happy for reviews and comments. Please note if you review (especially the > core parts), I'd like to have a short summary of your review even if there is > no proposed change. Like what you did, what you think about it, etc. Some stuff > in here is subtle, so if you went through the effort to double check my > assumptions you should name it :) > Thank you! FWIW, Reviewed-by Andy Shevchenko <andriy.shevchenko@xxxxxxxxxxxxxxx> for patches 1-5,12. Indeed, atomic condition sounds clear now. > > Finally, a big thank you and credit to Renesas for funding this work, of course! > > Happy hacking, > > Wolfram > > [1] https://lkml.org/lkml/2019/3/2/76 > [2] http://patchwork.ozlabs.org/patch/1067437/ > > Wolfram Sang (12): > i2c: remove use of in_atomic() > i2c: core: use I2C locking behaviour also for SMBUS > i2c: core: introduce callbacks for atomic transfers > i2c: mux: populate the new *_atomic callbacks > i2c: demux: handle the new atomic callbacks > i2c: omap: Add the master_xfer_irqless hook > i2c: tegra-bpmp: convert to use new atomic callbacks > i2c: ocores: refactor setup for polling > i2c: ocores: enable atomic xfers > i2c: stu300: use xfer_atomic callback to bail out early > i2c: algo: bit: add flag to whitelist atomic transfers > i2c: gpio: flag atomic capability if possible > > drivers/i2c/algos/i2c-algo-bit.c | 22 +++++++++- > drivers/i2c/busses/i2c-gpio.c | 2 + > drivers/i2c/busses/i2c-ocores.c | 16 +++----- > drivers/i2c/busses/i2c-omap.c | 76 +++++++++++++++++++++++++++++------ > drivers/i2c/busses/i2c-stu300.c | 25 +++++------- > drivers/i2c/busses/i2c-tegra-bpmp.c | 25 +++++++++--- > drivers/i2c/i2c-core-base.c | 17 ++++---- > drivers/i2c/i2c-core-smbus.c | 25 +++++++++--- > drivers/i2c/i2c-core.h | 25 ++++++++++++ > drivers/i2c/i2c-mux.c | 6 +++ > drivers/i2c/muxes/i2c-demux-pinctrl.c | 2 + > include/linux/i2c-algo-bit.h | 1 + > include/linux/i2c.h | 15 +++++-- > 13 files changed, 194 insertions(+), 63 deletions(-) > > -- > 2.11.0 > -- With Best Regards, Andy Shevchenko
