[PATCH v5 2/2] mfd: simple-mfd-i2c: add a reboot cell for the SpacemiT P1 chip

[Yanko Kaneti]

Hello,

On Mon, 2026-03-02 at 21:08 +0100, Aurelien Jarno wrote:
> On 2026-03-01 23:16, Aurelien Jarno wrote:
> > On 2026-02-27 13:29, Yanko Kaneti wrote:
> > > On Thu, 2026-02-26 at 22:32 +0100, Aurelien Jarno wrote:
> > > > Hi,
> > > > 
> > > > On 2026-02-26 16:32, Yanko Kaneti wrote:
> > > > > Hello,
> > > > > 
> > > > > On Mon, 2025-11-03 at 00:02 +0100, Aurelien Jarno wrote:
> > > > > > Add a "spacemit-p1-reboot" cell for the SpacemiT P1 chip.
> > > > > > 
> > > > > > Signed-off-by: Aurelien Jarno <aurelien at aurel32.net>
> > > > > > ---
> > > > > > v5: no changes
> > > > > > 
> > > > > >  drivers/mfd/simple-mfd-i2c.c | 1 +
> > > > > >  1 file changed, 1 insertion(+)
> > > > > > 
> > > > > > diff --git a/drivers/mfd/simple-mfd-i2c.c b/drivers/mfd/simple-mfd-i2c.c
> > > > > > index 0a607a1e3ca1d..542d378cdcd1f 100644
> > > > > > --- a/drivers/mfd/simple-mfd-i2c.c
> > > > > > +++ b/drivers/mfd/simple-mfd-i2c.c
> > > > > > @@ -99,6 +99,7 @@ static const struct regmap_config spacemit_p1_regmap_config = {
> > > > > >  };
> > > > > >  
> > > > > >  static const struct mfd_cell spacemit_p1_cells[] = {
> > > > > > +	{ .name = "spacemit-p1-reboot", },
> > > > > >  	{ .name = "spacemit-p1-regulator", },
> > > > > >  	{ .name = "spacemit-p1-rtc", },
> > > > > >  };
> > > > > 
> > > > > Perhaps its safe to merge this one now that everything P1 and I2C is
> > > > > already in linus tip ?
> > > > 
> > > > Unfortunately, this patchset is still missing:
> > > > https://lore.kernel.org/all/20260207-b4-k3-i2c-pio-v7-0-626942d94d91@linux.spacemit.com/
> > > > 
> > > > This means the reboots work most of the time, but are not 100% reliable, 
> > > > and that's the reason why this patch got blocked from merging.
> > > 
> > > I see. Thanks. Sounds to me like sometimes working compared to never
> > > working is better , but anyway..
> > 
> > I agree with that, but the decision was to hold on this patch until the 
> > I2C PIO part got merged.
> > 
> > > FWIW  with this patch and the pio patcheset I get this rcu splat on
> > > reboot (which is still working). Similar splat is there without the pio
> > > patcheset.
> > 
> > I haven't been able to reproduce the issue here after 10+ reboots on a 
> > BPI-F3 board, but I tried the patch on top of 6.19. I'll try to build a 
> > 7.0.0-rc2 kernel and report back.
> 
> I have tried that, and I am still unable to reproduce the issue with a 
> 7.0.0-rc2 kernel and a BPI-F3 board.

I can still see it on every reboot (with the patches that allow reboot
to work). Do you have CONFIG_PREEMPT_RCU in your config ? its default on
when anything PREEMPT is selected. In Fedora its CONFIG_PREEMPT_DYNAMIC
that flips it.

Regards
Yanko