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The hardware manual says that software should attempt a new dynamic config access (be it a a write or a read-back) only while the VALID bit is cleared. The VALID bit is set by software to 1, and it remains set as long as the hardware is still processing the request. Currently the driver only polls for the command completion only for reads, because that's when we need the actual data read back. Writes have been more or less "asynchronous", although this has never been an observable issue. This change makes sja1105_dynamic_config_write poll the VALID bit as well, to absolutely ensure that a follow-up access to the static config finds the VALID bit cleared. So VALID means "work in progress", while VALIDENT means "entry being read is valid". On reads we check the VALIDENT bit too, while on writes that bit is not always defined. So we need to factor it out of the loop, and make the loop provide back the unpacked command structure, so that sja1105_dynamic_config_read can check the VALIDENT bit. The change also attempts to convert the open-coded loop to use the read_poll_timeout macro, since I know this will come up during review. It's more code, but hey, it uses read_poll_timeout! Tested on SJA1105T, SJA1105S, SJA1110A. Signed-off-by: Vladimir Oltean <vladimir.oltean@nxp.com> Signed-off-by: David S. Miller <davem@davemloft.net>
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.