[PATCH RESEND 1/2] drivers: clk: zynqmp: calculate closest mux rate
Buddhabhatti, Jay
jay.buddhabhatti at amd.com
Wed Oct 25 05:24:25 PDT 2023
Hi Stephen,
> -----Original Message-----
> From: Stephen Boyd <sboyd at kernel.org>
> Sent: Tuesday, October 24, 2023 9:09 AM
> To: Buddhabhatti, Jay <jay.buddhabhatti at amd.com>; Simek, Michal
> <michal.simek at amd.com>; mturquette at baylibre.com
> Cc: linux-clk at vger.kernel.org; linux-arm-kernel at lists.infradead.org; linux-
> kernel at vger.kernel.org; Buddhabhatti, Jay <jay.buddhabhatti at amd.com>
> Subject: Re: [PATCH RESEND 1/2] drivers: clk: zynqmp: calculate closest mux
> rate
>
> Quoting Jay Buddhabhatti (2023-10-16 04:30:01)
> > Currently zynqmp clock driver is not calculating closest mux rate and
> > because of that Linux is not setting proper frequency for CPU and not
> > able to set given frequency for dynamic frequency scaling.
> >
> > E.g., In current logic initial acpu clock parent and frequency as below
> > apll1 0 0 0 2199999978 0 0 50000 Y
> > acpu0_mux 0 0 0 2199999978 0 0 50000 Y
> > acpu0_idiv1 0 0 0 2199999978 0 0 50000 Y
> > acpu0 0 0 0 2199999978 0 0 50000 Y
> >
> > After changing acpu frequency to 549999994 Hz using CPU freq scaling
> > its selecting incorrect parent which is not closest frequency.
> > rpll_to_xpd 0 0 0 1599999984 0 0 50000 Y
> > acpu0_mux 0 0 0 1599999984 0 0 50000 Y
> > acpu0_div1 0 0 0 533333328 0 0 50000 Y
> > acpu0 0 0 0 533333328 0 0 50000 Y
> >
> > Parent should remain same since 549999994 = 2199999978 / 4.
> >
> > So use __clk_mux_determine_rate_closest() generic function to
> > calculate closest rate for mux clock. After this change its selecting
> > correct parent and correct clock rate.
> > apll1 0 0 0 2199999978 0 0 50000 Y
> > acpu0_mux 0 0 0 2199999978 0 0 50000 Y
> > acpu0_div1 0 0 0 549999995 0 0 50000 Y
> > acpu0 0 0 0 549999995 0 0 50000 Y
> >
> > Signed-off-by: Jay Buddhabhatti <jay.buddhabhatti at amd.com>
> > ---
>
> Any Fixes tag here?
[Jay] Sure I will add fixes tag.
Thanks,
Jay
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