netdev - Re: [PATCH net] net: ethernet: renesas: rswitch Fix PHY station management clock setting

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-ID: <CAMuHMdV4THYuBLTDOnpL+HyQqEpk69F4ZsM4d6+HX4EnDE2EmA@mail.gmail.com>
Date: Tue, 26 Sep 2023 09:18:31 +0200
From: Geert Uytterhoeven <geert@...ux-m68k.org>
To: Andrew Lunn <andrew@...n.ch>
Cc: Yoshihiro Shimoda <yoshihiro.shimoda.uh@...esas.com>, s.shtylyov@....ru, 
	davem@...emloft.net, edumazet@...gle.com, kuba@...nel.org, pabeni@...hat.com, 
	netdev@...r.kernel.org, linux-renesas-soc@...r.kernel.org, 
	Tam Nguyen <tam.nguyen.xa@...esas.com>, 
	Kuninori Morimoto <kuninori.morimoto.gx@...esas.com>
Subject: Re: [PATCH net] net: ethernet: renesas: rswitch Fix PHY station
 management clock setting

On Tue, Sep 26, 2023 at 8:45 AM Andrew Lunn <andrew@...n.ch> wrote:
> On Mon, Sep 25, 2023 at 09:34:16AM +0900, Yoshihiro Shimoda wrote:
> > From: Tam Nguyen <tam.nguyen.xa@...esas.com>
> >
> > Fix the MPIC.PSMCS value following the programming example in the
> > section 6.4.2 Management Data Clock (MDC) Setting, Ethernet MAC IP,
> > S4 Hardware User Manual Rev.1.00.
> >
> > The value is calculated by
> >     MPIC.PSMCS = clk[MHz] / ((MDC frequency[MHz] + 1) * 2)
> > with the input clock frequency of 320MHz and MDC frequency of 2.5MHz.
> > Otherwise, this driver cannot communicate PHYs on the R-Car S4 Starter
> > Kit board.
>
> If you run this calculation backwards, what frequency does
> MPIC_PSMCS(0x3f) map to?
>
> Is 320MHz really fixed? For all silicon variants? Is it possible to do
> a clk_get_rate() on a clock to get the actual clock rate?

With debugfs enabled, one can just look at /sys/kernel/debug/clk/clk_summary.

Gr{oetje,eeting}s,

                        Geert

-- 
Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- geert@...ux-m68k.org

In personal conversations with technical people, I call myself a hacker. But
when I'm talking to journalists I just say "programmer" or something like that.
                                -- Linus Torvalds