Re: [PATCH] arm: dts: k3-am625-verdin-r5: Change CPU frequency to 1000MHz

[Francesco Dolcini <francesco@dolcini.it>]

On Tue, Feb 20, 2024 at 10:47:03AM +0530, Vignesh Raghavendra wrote:
> 
> 
> On 19/02/24 18:04, Vitor Soares wrote:
> > From: Vitor Soares <vitor.soares@toradex.com>
> > 
> > The same U-Boot binary is compatible with multiple Verdin AM62 board
> > variants. However, some of the SoC models can only operate at a maximum
> > speed of 1 GHz.
> > 
> > Previously, the boards with lower-speed grades were running at
> > overclocked speeds, leading to kernel complaints about unsupported
> > configurations.
> > 
> > To resolve this issue, the operating speed has been decreased to the
> > maximum allowable value across all Verdin AM62 board variants. As a
> > result, there is a regression in overall boot time, increasing by around
> > 200 milliseconds for the faster SoC variant.
> > 
> 
> Patch as such is fine. But one way to avoid boot regression is to fixup
> the clock freq using based on speed grade identified by
> k3_get_speed_grade() and freq mapping table for each letter as show in
> datasheet [0]

Ack. I would still merge this as it is, I think that is conceptually
better to have a safe and valid value in the DT source file.

We can still do the optimization you suggested afterward, we just wanted
to get rid of any potential malfunction because of this overclocking as
soon as possible.

Francesco