linux-kernel - Re: (subset) [PATCH v5 0/2] driver: reset: spacemit-p1: add driver for poweroff/reboot

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Message-ID: <751C70A7BC663B0E+aQvz-ASa-z4fvGiO@kernel.org>
Date: Thu, 6 Nov 2025 09:03:52 +0800
From: Troy Mitchell <troy.mitchell@...ux.spacemit.com>
To: Troy Mitchell <troy.mitchell@...ux.spacemit.com>,
	Lee Jones <lee@...nel.org>,
	Sebastian Reichel <sebastian.reichel@...labora.com>,
	linux-kernel@...r.kernel.org, Sebastian Reichel <sre@...nel.org>,
	Yixun Lan <dlan@...too.org>, Paul Walmsley <pjw@...nel.org>,
	Palmer Dabbelt <palmer@...belt.com>,
	Albert Ou <aou@...s.berkeley.edu>, Alexandre Ghiti <alex@...ti.fr>,
	linux-riscv@...ts.infradead.org, spacemit@...ts.linux.dev,
	linux-pm@...r.kernel.org
Subject: Re: (subset) [PATCH v5 0/2] driver: reset: spacemit-p1: add driver
 for poweroff/reboot

On Wed, Nov 05, 2025 at 11:49:37PM +0100, Aurelien Jarno wrote:
> On 2025-11-05 17:42, Troy Mitchell wrote:
> > On Wed, Nov 05, 2025 at 09:34:21AM +0000, Lee Jones wrote:
> > > On Tue, 04 Nov 2025, Troy Mitchell wrote:
> > > 
> > > > On Mon, Nov 03, 2025 at 01:48:33AM +0100, Sebastian Reichel wrote:
> > > > > 
> > > > > On Mon, 03 Nov 2025 00:01:58 +0100, Aurelien Jarno wrote:
> > > > > > This adds poweroff/reboot support for the SpacemiT P1 PMIC chip, which is
> > > > > > commonly paired with the SpacemiT K1 SoC.
> > > > > > 
> > > > > > Note: For reliable operation, this driver depends on a this patch that adds
> > > > > > atomic transfer support to the SpacemiT I2C controller driver:
> > > > > >   https://lore.kernel.org/spacemit/20251009-k1-i2c-atomic-v4-1-a89367870286@linux.spacemit.com/
> > ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
> > dependency is here.
> 
> Oh indeed, I have forgotten about this part.
> 
> > > > > > 
> > > > > > [...]
> > > > > 
> > > > > Applied, thanks!
> > > > > 
> > > > > [1/2] driver: reset: spacemit-p1: add driver for poweroff/reboot
> > > > >       commit: 28124cc0fb8c7dc01a6834d227351e25d9a92c58
> > > > Should we apply it now? The dependency patch hasn’t been merged yet...
> > > 
> > > What is the dependency?
> > I point it out above.
> > Without this patch, reboot and shutdown would end up calling the non-atomic i2c_transfer.
> 
> Note however this is not a strong dependency, it is needed to make the 
> reset or power off reliable. Calling non-atomic i2c_transfer lead to a 
> successful reset or power off a bit more than half of the time.
Oh really? I never had success with the non-atomic transfer.

But however, as Lee pointed out, this patch doesn’t need to do
anything special now.
We only needs to ensure that the MFD part won’t be probed.

                          - Troy
> 
> Regards
> Aurelien
> 
> -- 
> Aurelien Jarno                          GPG: 4096R/1DDD8C9B
> aurelien@...el32.net                     http://aurel32.net
>