Re: [PATCH v5] clk: bcm2835: Round UART input clock up

[Stephen Boyd <sboyd@kernel.org>]

Quoting Ivan T. Ivanov (2022-09-12 01:13:04)
> It was reported that RPi3[1] and RPi Zero 2W boards have issues with
> the Bluetooth. It turns out that when switching from initial to
> operation speed host and device no longer can talk each other because
> host uses incorrect UART baud rate.
> 
> The UART driver used in this case is amba-pl011. Original fix, see
> below Github link[2], was inside pl011 module, but somehow it didn't
> look as the right place to fix. Beside that this original rounding
> function is not exactly perfect for all possible clock values. So I
> deiced to move the hack to the platform which actually need it.
> 
> The UART clock is initialised to be as close to the requested
> frequency as possible without exceeding it. Now that there is a
> clock manager that returns the actual frequencies, an expected
> 48MHz clock is reported as 47999625. If the requested baud rate
> == requested clock/16, there is no headroom and the slight
> reduction in actual clock rate results in failure.
> 
> If increasing a clock by less than 0.1% changes it from ..999..
> to ..000.., round it up.
> 
> [1] https://bugzilla.suse.com/show_bug.cgi?id=1188238
> [2] https://github.com/raspberrypi/linux/commit/ab3f1b39537f6d3825b8873006fbe2fc5ff057b7
> 
> Cc: Phil Elwell <phil@raspberrypi.com>
> Signed-off-by: Ivan T. Ivanov <iivanov@suse.de>
> Reviewed-by: Stefan Wahren <stefan.wahren@i2se.com>
> ---

Applied to clk-next

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