linux-kernel - Re: [PATCH v2 3/3] riscv: dts: thead: add basic spi node

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Message-ID: <Zobhkf5qr13rKcWH@x1>
Date: Thu, 4 Jul 2024 10:53:21 -0700
From: Drew Fustini <drew@...7.com>
To: Drew Fustini <pdp7pdp7@...il.com>
Cc: Conor Dooley <conor@...nel.org>,
	Kanak Shilledar <kanakshilledar@...il.com>,
	Serge Semin <fancer.lancer@...il.com>,
	Mark Brown <broonie@...nel.org>, Rob Herring <robh@...nel.org>,
	Krzysztof Kozlowski <krzk+dt@...nel.org>,
	Conor Dooley <conor+dt@...nel.org>,
	Jisheng Zhang <jszhang@...nel.org>, Guo Ren <guoren@...nel.org>,
	Fu Wei <wefu@...hat.com>, Paul Walmsley <paul.walmsley@...ive.com>,
	Palmer Dabbelt <palmer@...belt.com>,
	Albert Ou <aou@...s.berkeley.edu>, linux-spi@...r.kernel.org,
	devicetree@...r.kernel.org, linux-kernel@...r.kernel.org,
	linux-riscv@...ts.infradead.org
Subject: Re: [PATCH v2 3/3] riscv: dts: thead: add basic spi node

On Thu, Jul 04, 2024 at 09:59:20AM -0700, Drew Fustini wrote:
> On Wed, Jul 03, 2024 at 03:45:37PM +0100, Conor Dooley wrote:
> > Kanak, Drew,
> > 
> > On Mon, Jul 01, 2024 at 05:43:54PM +0530, Kanak Shilledar wrote:
> > > created spi0 node with fixed clock. the spi0 node
> > > uses synopsis designware driver and has the following
> > > compatible "snps,dw-apb-ssi". the spi0 node is connected
> > > to a SPI NOR flash pad which is left unpopulated on the back
> > > side of the board.
> > > 
> > > Signed-off-by: Kanak Shilledar <kanakshilledar@...il.com>
> > > ---
> > > Changes in v2:
> > > - Separated from a single patch file
> > > ---
> > >  .../boot/dts/thead/th1520-beaglev-ahead.dts      |  9 +++++++++
> > >  .../boot/dts/thead/th1520-lichee-module-4a.dtsi  |  4 ++++
> > >  .../riscv/boot/dts/thead/th1520-lichee-pi-4a.dts |  5 +++++
> > 
> > Didn't you say there was a flash on one of these two boards?
> > 
> > >  arch/riscv/boot/dts/thead/th1520.dtsi            | 16 ++++++++++++++++
> > >  4 files changed, 34 insertions(+)
> > > 
> > > diff --git a/arch/riscv/boot/dts/thead/th1520-beaglev-ahead.dts b/arch/riscv/boot/dts/thead/th1520-beaglev-ahead.dts
> > > index d9b4de9e4757..3103b74e0288 100644
> > > --- a/arch/riscv/boot/dts/thead/th1520-beaglev-ahead.dts
> > > +++ b/arch/riscv/boot/dts/thead/th1520-beaglev-ahead.dts
> > > @@ -17,6 +17,7 @@ aliases {
> > >  		gpio1 = &gpio1;
> > >  		gpio2 = &gpio2;
> > >  		gpio3 = &gpio3;
> > > +		spi0 = &spi0;
> > 
> > "spi" would sort after "serial".
> > 
> > >  		serial0 = &uart0;
> > >  		serial1 = &uart1;
> > >  		serial2 = &uart2;
> > > @@ -52,6 +53,10 @@ &sdhci_clk {
> > >  	clock-frequency = <198000000>;
> > >  };
> > >  
> > > +&spi_clk {
> > > +	clock-frequency = <396000000>;
> > > +};
> > 
> > I'm pretty sceptical about adding more of these fixed clocks, rather
> > than waiting for the clock driver. Drew, what do you think? Should we
> > just add one more to your fixup list or would you rather delay? Guess it
> > depends on how long more you think that clock driver is likely to take.
> 
> I think the clk driver [1] is in good shape but it has not been reviewed
> by the clk maintainer yet. Thus it is hard to predict any timeline for
> it getting merged.
> 
> SPI support doesn't require any driver changes so I'd be inclined to
> allow the fixed clock in this case. It will be simple to change it over
> to a real clock once the clk driver is upstream.
> 
> Acked-by: Drew Fustini <drew@...7.com>
> 
> Thanks,
> Drew

Sorry, I meant to include the link to the most recent clk series:
https://lore.kernel.org/linux-riscv/20240623-th1520-clk-v2-0-ad8d6432d9fb@tenstorrent.com/

-Drew