Re: [PATCH v4 7/8] soc: starfive: Add socinfo driver for JHB100 SoC

From: Conor Dooley <conor@kernel.org>
To: Changhuang Liang <changhuang.liang@starfivetech.com>
Cc: Michael Turquette <mturquette@baylibre.com>,
	Rob Herring <robh@kernel.org>,
	Krzysztof Kozlowski <krzk+dt@kernel.org>,
	Conor Dooley <conor+dt@kernel.org>,
	Stephen Boyd <sboyd@kernel.org>,
	Brian Masney <bmasney@redhat.com>, Paul Walmsley <pjw@kernel.org>,
	Palmer Dabbelt <palmer@dabbelt.com>,
	Albert Ou <aou@eecs.berkeley.edu>,
	Alexandre Ghiti <alex@ghiti.fr>,
	Philipp Zabel <p.zabel@pengutronix.de>,
	Emil Renner Berthing <kernel@esmil.dk>,
	Chen Wang <unicorn_wang@outlook.com>,
	Inochi Amaoto <inochiama@gmail.com>,
	Alexey Charkov <alchark@gmail.com>,
	Thomas Bogendoerfer <tsbogend@alpha.franken.de>,
	Keguang Zhang <keguang.zhang@gmail.com>,
	"linux-clk@vger.kernel.org" <linux-clk@vger.kernel.org>,
	"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
	"devicetree@vger.kernel.org" <devicetree@vger.kernel.org>,
	"linux-riscv@lists.infradead.org"
	<linux-riscv@lists.infradead.org>
Subject: Re: [PATCH v4 7/8] soc: starfive: Add socinfo driver for JHB100 SoC
Date: Thu, 13 Aug 2026 17:46:31 +0100	[thread overview]
Message-ID: <20260813-presoak-scarily-b6cdecfcb7cc@spud> (raw)
In-Reply-To: <ZQ4PR01MB1202F016AD1F1E699429DDC0F2DB2@ZQ4PR01MB1202.CHNPR01.prod.partner.outlook.cn>

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On Thu, Aug 13, 2026 at 08:10:12AM +0000, Changhuang Liang wrote:
> Hi ,Conor
> 
> Thanks for the review.
> 
> > On Wed, Aug 12, 2026 at 10:37:16AM +0000, Changhuang Liang wrote:
> > > Hi, Conor
> > >
> > > Thanks for the review.
> > >
> > > > On Tue, Aug 11, 2026 at 05:36:19AM +0000, Changhuang Liang wrote:
> > > >
> > > > > > On Sat, Aug 08, 2026 at 06:50:53PM -0700, Changhuang Liang wrote:
> > > >
> > > > > > > +static int __init starfive_socinfo_init(void) {
> > > > > > > +	struct soc_device_attribute *attrs;
> > > > > > > +	struct soc_device *soc_dev;
> > > > > > > +	const char *machine = NULL;
> > > > > > > +	struct device_node *np;
> > > > > > > +	struct regmap *regmap;
> > > > > > > +	char rev_char;
> > > > > > > +	u32 rev_id;
> > > > > > > +	int ret;
> > > > > > > +
> > > > > > > +	np = of_find_compatible_node(NULL, NULL,
> > > > > > > +"starfive,jhb100-sys0-syscon");
> > > > > >
> > > > > > Remind me again why this is not just probed as an mfd cell from
> > > > > > the syscon driver?
> > > > > >
> > > > > > (Hint: please put this info in the commit message).
> > > > >
> > > > > The discussion result with Krzysztof at that time is recorded here:
> > > > > https://lore.kernel.org/all/20260405-strong-watchful-marmot-fdfad6
> > > > > @quo
> > > > > ll/
> > > > >
> > > > > One register should not be treated as a separate device node.
> > > >
> > > > That's a different question. In the case of an mfd cell probed from
> > > > the syscon driver there would be no devicetree modifications
> > > > required compared to what you have now. e.g. sg2044-topsys.c
> > >
> > > This seems feasible, and I can introduce this modification in the next
> > version.
> > 
> > 
> > In fact, you don't even need the mfd cell, because your driver is going to be in
> > drivers/soc/starfive anyway? You can just bind directly to the
> > sys0 syscon I think.
> 
> I suddenly realized that I missed one issue: starfive,jhb100-sys0-syscon is already 
> bound to the PLL driver by default, I can't use it to bind another device anymore. 
> 
> which is why I used 
> 
> np = of_find_compatible_node(NULL, NULL, "starfive,jhb100-sys0-syscon"); 
> 
> in jhb100-socinfo.c.
> 
> So it seems the MFD cell approach isn't really feasible either?

You could, in that case, probe the clock driver using the mfd_cell like
sg2044-topsys. What else other than the pll controls and the soc info
register is in this register region?

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