linux-kernel - Re: [PATCH v5 3/9] reset: mpfs: add non-auxiliary bus probing

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Message-ID: <20251024-void-esteemed-832b3bf5b965@spud>
Date: Fri, 24 Oct 2025 11:07:03 +0100
From: Conor Dooley <conor@...nel.org>
To: Claudiu Beznea <claudiu.beznea@...on.dev>
Cc: Conor Dooley <conor.dooley@...rochip.com>,
	Daire McNamara <daire.mcnamara@...rochip.com>,
	pierre-henry.moussay@...rochip.com,
	valentina.fernandezalanis@...rochip.com,
	Michael Turquette <mturquette@...libre.com>,
	Stephen Boyd <sboyd@...nel.org>, Rob Herring <robh@...nel.org>,
	Krzysztof Kozlowski <krzk+dt@...nel.org>,
	Philipp Zabel <p.zabel@...gutronix.de>,
	linux-riscv@...ts.infradead.org, linux-clk@...r.kernel.org,
	devicetree@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH v5 3/9] reset: mpfs: add non-auxiliary bus probing

On Thu, Oct 23, 2025 at 07:06:48AM +0300, Claudiu Beznea wrote:
> Hi, Conor,
> 
> On 10/13/25 20:45, Conor Dooley wrote:
> > From: Conor Dooley <conor.dooley@...rochip.com>
> > 
> > While the auxiliary bus was a nice bandaid, and meant that re-writing
> > the representation of the clock regions in devicetree was not required,
> > it has run its course. The "mss_top_sysreg" region that contains the
> > clock and reset regions, also contains pinctrl and an interrupt
> > controller, so the time has come rewrite the devicetree and probe the
> > reset controller from an mfd devicetree node, rather than implement
> > those drivers using the auxiliary bus. Wanting to avoid propagating this
> > naive/incorrect description of the hardware to the new pic64gx SoC is a
> > major motivating factor here.
> > 
> > Signed-off-by: Conor Dooley <conor.dooley@...rochip.com>
> > ---
> > v4:
> > - Only use driver specific lock for non-regmap writes
> > 
> > v2:
> > - Implement the request to use regmap_update_bits(). I found that I then
> >   hated the read/write helpers since they were just bloat, so I ripped
> >   them out. I replaced the regular spin_lock_irqsave() stuff with a
> >   guard(spinlock_irqsave), since that's a simpler way of handling the two
> >   different paths through such a trivial pair of functions.
> > ---
> >  drivers/reset/reset-mpfs.c | 83 ++++++++++++++++++++++++++++++--------
> >  1 file changed, 66 insertions(+), 17 deletions(-)
> > 
> > diff --git a/drivers/reset/reset-mpfs.c b/drivers/reset/reset-mpfs.c
> > index f6fa10e03ea8..8e5ed4deecf3 100644
> > --- a/drivers/reset/reset-mpfs.c
> > +++ b/drivers/reset/reset-mpfs.c
> > @@ -7,13 +7,16 @@
> >   *
> >   */
> >  #include <linux/auxiliary_bus.h>
> > +#include <linux/cleanup.h>
> >  #include <linux/delay.h>
> >  #include <linux/io.h>
> > +#include <linux/mfd/syscon.h>
> 
> Should you add a depends on MFD_SYSCON ?

Perhaps, but it's a NOP. This driver depends on the clock driver, which
does have a depends on MFD_SYSCON. I'll add it, but makes no difference
to either the build or functionality.

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