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What to do when the real rate of the gpmi clock is not equal to the required one? The solutions proposed in [1] did not lead to a conclusion on how to validate the clock rate, so, inspired by the document [2], I consider the rate correct only if not lower or equal to the rate of the previous edo mode. In fact, in chapter 4.16.2 (NV-DDR) of the document [2], it is written that "If the host selects timing mode n, then its clock period shall be faster than the clock period of timing mode n-1 and slower than or equal to the clock period of timing mode n.". I thought that it could therefore also be used in this case, without therefore having to define the valid rate ranges empirically. For example, suppose that gpmi_nfc_compute_timings() is called to set edo mode 5 (100MHz) but the rate returned by clk_round_rate() is 80MHz (edo mode 4). In this case gpmi_nfc_compute_timings() will return error, and will be called again to set edo mode 4, which this time will be successful. [1] https://lore.kernel.org/r/20210702065350.209646-5-ebiggers@kernel.org [2] http://www.onfi.org/-/media/client/onfi/specs/onfi_3_0_gold.pdf?la=en Co-developed-by: Michael Trimarchi <michael@amarulasolutions.com> Signed-off-by: Michael Trimarchi <michael@amarulasolutions.com> Signed-off-by: Dario Binacchi <dario.binacchi@amarulasolutions.com> Tested-by: Sascha Hauer <s.hauer@pengutronix.de> Reviewed-by: Sascha Hauer <s.hauer@pengutronix.de> Signed-off-by: Miquel Raynal <miquel.raynal@bootlin.com> Link: https://lore.kernel.org/linux-mtd/20220118095434.35081-4-dario.binacchi@amarulasolutions.com
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.