RE: [PATCH] clk: renesas: rzg2l-cpg: Skip re-initializing MSTOPs and critical resets for s2idle

[Biju Das]

Hi Claudiu,

> -----Original Message-----
> From: Claudiu Beznea <claudiu.beznea@xxxxxxxxxx>
> Sent: 19 October 2026 14:00
> Subject: Re: [PATCH] clk: renesas: rzg2l-cpg: Skip re-initializing MSTOPs and critical resets for s2idle
> 
> Hi, Biju,
> 
> On 10/19/26 15:36, Biju Das wrote:
> > Hi Claudiu,
> >
> >> -----Original Message-----
> >> From: Claudiu Beznea <claudiu.beznea@xxxxxxxxxx>
> >> Sent: 19 October 2026 13:25
> >> Subject: [PATCH] clk: renesas: rzg2l-cpg: Skip re-initializing MSTOPs
> >> and critical resets for s2idle
> >>
> >> From: Claudiu Beznea <claudiu.beznea.uj@xxxxxxxxxxxxxx>
> >>
> >> When the system suspends to s2idle, any of the IP blocks may be in
> >> the wakeup path. For a device in the wakeup path, the generic PM
> >> domain (genpd) does not disable/enable its clocks across
> >> suspend/resume. Re- initializing the MSTOP bits for such a device leads to synchronous aborts when its
> registers are accessed for the first time after resume.
> >>
> >> In a suspend mode that is not controlled by firmware, power to the
> >> SoC is not lost, so the MSTOP and critical reset state is retained
> >> and does not need re-initialization in the first place. Skip it when
> >> pm_suspend_via_firmware() reports such a mode.
> >>
> >> Fixes: 5cd33db56956 ("clk: renesas: rzg2l: Add support for MSTOP in
> >> clock enable/disable API")
> >> Cc: stable@xxxxxxxxxxxxxxx
> >> Signed-off-by: Claudiu Beznea <claudiu.beznea.uj@xxxxxxxxxxxxxx>
> >> ---
> >>   drivers/clk/renesas/rzg2l-cpg.c | 4 ++++
> >>   1 file changed, 4 insertions(+)
> >>
> >> diff --git a/drivers/clk/renesas/rzg2l-cpg.c
> >> b/drivers/clk/renesas/rzg2l-cpg.c index
> >> f6293c968bcf..3d2281456036 100644
> >> --- a/drivers/clk/renesas/rzg2l-cpg.c
> >> +++ b/drivers/clk/renesas/rzg2l-cpg.c
> >> @@ -31,6 +31,7 @@
> >>   #include <linux/reset-controller.h>
> >>   #include <linux/slab.h>
> >>   #include <linux/string_choices.h>
> >> +#include <linux/suspend.h>
> >>   #include <linux/units.h>
> >>
> >>   #include <dt-bindings/clock/renesas-cpg-mssr.h>
> >> @@ -2697,6 +2698,9 @@ static int rzg2l_cpg_resume(struct device *dev)
> >>   	struct rzg2l_cpg_priv *priv = dev_get_drvdata(dev);
> >>   	int ret;
> >>
> >> +	if (!pm_suspend_via_firmware())
> >> +		return 0;
> >> +
> >
> > Please move this after deassert, otherwise it will lead to SCIF not
> > getting console prompt during s2idle as reset is asserted during suspend?
> How did you reproduce this?
> 
> Who asserts the SCIF reset in s2idle?

For getting SCIF interrupts, DMA needs to be deasseted. That is the reason
DMA is defined as critical reset. During suspend [1] get asserted,
but assert will be skipped by [2]. So your code looks ok.

[1]
https://git.kernel.org/pub/scm/linux/kernel/git/next/linux-next.git/tree/drivers/dma/sh/rz-dmac.c?h=next-20261016#n1591

[2]
 https://git.kernel.org/pub/scm/linux/kernel/git/next/linux-next.git/tree/drivers/clk/renesas/rzg2l-cpg.c?h=next-20261016#n2380

Cheers,
Biju