On 4/12/2017 20:36, Wolfram Sang wrote:
When implementing bus recovery for the i2c-rcar driver, two problems were
encountered: 1) When reading the SDA bit, not the SDA status was returned but
the internal state of the "bus_is_busy" logic. 2) This logic needs a STOP to
consider the bus free again. SCL/SDA high is not enough, and there is no other
way known to reset the internal logic otherwise.
The obvious solution to just send STOP after recovery makes sense for the
generic case, too, IMO. If we made a device release SDA again, and are about
start a new transfer using START, then we should terminate the previous state
properly with STOP. This may help with some devices and shouldn't create any
drawback AFAICS.
For this, we need to introduce a 'set_sda' callback to the recovery
infrastructure. Because of this and some other minor recovery core changes, I
CCed a few people working on I2C bus recovery recently. The first five patches
may be interesting for you, so your input is greatly appreciated. Also, testing
the new features with GPIO based recovery would be awesome to have.
This was tested on a Renesas Lager board (r8a7790/R-Car H2). My test procedure
is documented here:
Patches 1-5.
Tested-by: Phil Reid <pr...@electromag.com.au>
--
Regards
Phil Reid
