6d6b0d0d5a
When in slave mode, an arbitration loss (ARLO) may be detected before the
slave had a chance to detect the stop condition (STOPF in ISR).
This is seen when two master + slave adapters switch their roles. It
provokes the i2c bus to be stuck, busy as SCL line is stretched.
- the I2C_SLAVE_STOP event is never generated due to STOPF flag is set but
don't generate an irq (race with ARLO irq, STOPIE is masked). STOPF flag
remains set until next master xfer (e.g. when STOPIE irq get unmasked).
In this case, completion is generated too early: immediately upon new
transfer request (then it doesn't send all data).
- Some data get stuck in TXDR register. As a consequence, the controller
stretches the SCL line: the bus gets busy until a future master transfer
triggers the bus busy / recovery mechanism (this can take time... and
may never happen at all)
So choice is to let the STOPF being detected by the slave isr handler,
to properly handle this stop condition. E.g. don't mask IRQs in error
handler, when the slave is running.
Fixes: 60d609f30de2 ("i2c: i2c-stm32f7: Add slave support")
Signed-off-by: Fabrice Gasnier <fabrice.gasnier@st.com>
Reviewed-by: Pierre-Yves MORDRET <pierre-yves.mordret@st.com>
Signed-off-by: Wolfram Sang <wsa@the-dreams.de>
Linux kernel
============
There are several guides for kernel developers and users. These guides can
be rendered in a number of formats, like HTML and PDF. Please read
Documentation/admin-guide/README.rst first.
In order to build the documentation, use ``make htmldocs`` or
``make pdfdocs``. The formatted documentation can also be read online at:
https://www.kernel.org/doc/html/latest/
There are various text files in the Documentation/ subdirectory,
several of them using the Restructured Text markup notation.
Please read the Documentation/process/changes.rst file, as it contains the
requirements for building and running the kernel, and information about
the problems which may result by upgrading your kernel.