mirror of
https://github.com/hardkernel/linux.git
synced 2026-06-07 03:15:31 +09:00
c0e00163f8
commit 521da1e9225450bd323db5fa5bca942b1dc485b7 upstream.
Frequently an I2C write will be followed by a read, such as a register
address write followed by a read of the register value. In this driver,
when the TX FIFO half empty interrupt was raised and it was determined
that there was enough space in the TX FIFO to send the following read
command, it would do so without waiting for the TX FIFO to actually
empty.
Unfortunately it appears that in some cases this can result in a NAK
that was raised by the target device on the write, such as due to an
unsupported register address, being ignored and the subsequent read
being done anyway. This can potentially put the I2C bus into an
invalid state and/or result in invalid read data being processed.
To avoid this, once a message has been fully written to the TX FIFO,
wait for the TX FIFO empty interrupt before moving on to the next
message, to ensure NAKs are handled properly.
Fixes: e1d5b6598c ("i2c: Add support for Xilinx XPS IIC Bus Interface")
Signed-off-by: Robert Hancock <robert.hancock@calian.com>
Cc: <stable@vger.kernel.org> # v2.6.34+
Reviewed-by: Manikanta Guntupalli <manikanta.guntupalli@amd.com>
Acked-by: Michal Simek <michal.simek@amd.com>
Signed-off-by: Andi Shyti <andi.shyti@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
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.