[PATCH] arm64: dts: imx8mp: Improve bluetooth UART on DH electronics i.MX8M Plus DHCOM

[Fabio Estevam]

Hi Marek,

On Tue, Jan 17, 2023 at 7:39 PM Marek Vasut <marex at denx.de> wrote:
>
> Use PLL1_80M instead of PLL3 to drive UART2 clock divided down to 80 MHz
> instead of 64 MHz to obtain suitable block clock for exact 4 Mbdps, which
> is the maximum supported baud rate by the muRata 2AE BT UART.
>
> The difference here is that at 64 MHz UART block clock, the clock with are
> divided by 16 (due to oversampling) to 4 MHz and the baud rate generator
> then needs to be set to UBIR+1/UBMR+1 = 1/1 to yield 4 Mbdps . In case of
> 80 MHz UART block clock divided by 16 to 5 MHz, the baud rate generator
> needs to be set to UBIR+1/UBMR+1 = 4/5 to yield 4 Mbdps .
>
> Both options are valid and yield the same result, except using the PLL1_80M
> output requires fewer clock tree changes, since the PLL1 already generates
> the 80 MHz usable for UART, which frees the PLL3 for other uses.

This looks like a good idea:

Reviewed-by: Fabio Estevam <festevam at denx.de>