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When a USB device is connected to the USB host port on the SAM9N12 then you get "-62" error which seems to indicate USB replies from the device are timing out. Based on a logic sniffer, I saw the USB bus was running at half speed. The PLL code uses cached MUL and DIV values which get set in set_rate() and applied in prepare(), but the recalc_rate() function instead queries the hardware instead of using these cached values. Therefore, if recalc_rate() is called between a set_rate() and prepare(), the wrong frequency is calculated and later the USB clock divider for the SAM9N12 SOC will be configured for an incorrect clock. In my case, the PLL hardware was set to 96 Mhz before the OHCI driver loads, and therefore the usb clock divider was being set to /2 even though the OHCI driver set the PLL to 48 Mhz. As an alternative explanation, I noticed this was fixed in the past by87e2ed338f("clk: at91: fix recalc_rate implementation of PLL driver") but the bug was later re-introduced by1bdf02326b("clk: at91: make use of syscon/regmap internally"). Fixes:1bdf02326b("clk: at91: make use of syscon/regmap internally) Cc: <stable@vger.kernel.org> Signed-off-by: Marcin Ziemianowicz <marcin@ziemianowicz.com> Acked-by: Boris Brezillon <boris.brezillon@bootlin.com> Signed-off-by: Stephen Boyd <sboyd@kernel.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.
See Documentation/00-INDEX for a list of what is contained in each file.
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.