linux-kernel - Re: [PATCH] arm64: dts: rockchip: Increase maximum frequency of SPI flash for ROCK Pi 4A/B/C

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Date: Sun, 17 Dec 2023 11:10:08 +0100
From: Stefan Nagy <stefan.nagy@...psilon.net>
To: Dragan Simic <dsimic@...jaro.org>
Cc: Heiko Stuebner <heiko@...ech.de>, linux-rockchip@...ts.infradead.org, 
	linux-arm-kernel@...ts.infradead.org, devicetree@...r.kernel.org, 
	linux-kernel@...r.kernel.org
Subject: Re: [PATCH] arm64: dts: rockchip: Increase maximum frequency of SPI
 flash for ROCK Pi 4A/B/C

Am Freitag, dem 15.12.2023 um 19:20 +0100 schrieb Dragan Simic:
> On 2023-12-15 19:15, Dragan Simic wrote:
> > On 2023-12-15 13:28, Stefan Nagy wrote:
> > > The ROCK Pi 4A/B/C boards come with a 32 Mbit SPI NOR flash chip
> > > (XTX Technology Limited XT25F32) which has a maximum clock
> > > frequency of 108 MHz. However, the Rockchip SPI controller driver
> > > limits the maximum SPI clock frequency to 50 MHz. Use this limit
> > > for spi-max-freq.
> > > 
> > > This patch has been tested on ROCK Pi 4A.
> > > 
> > > Signed-off-by: Stefan Nagy <stefan.nagy@...psilon.net>
> > > ---
> > >  arch/arm64/boot/dts/rockchip/rk3399-rock-pi-4a.dts | 2 +-
> > >  arch/arm64/boot/dts/rockchip/rk3399-rock-pi-4b.dts | 2 +-
> > >  arch/arm64/boot/dts/rockchip/rk3399-rock-pi-4c.dts | 2 +-
> > >  3 files changed, 3 insertions(+), 3 deletions(-)
> > > 
> > > diff --git a/arch/arm64/boot/dts/rockchip/rk3399-rock-pi-4a.dts
> > > b/arch/arm64/boot/dts/rockchip/rk3399-rock-pi-4a.dts
> > > index d5df8939a..30e63e62a 100644
> > > --- a/arch/arm64/boot/dts/rockchip/rk3399-rock-pi-4a.dts
> > > +++ b/arch/arm64/boot/dts/rockchip/rk3399-rock-pi-4a.dts
> > > @@ -19,6 +19,6 @@ &spi1 {
> > >         flash@0 {
> > >                 compatible = "jedec,spi-nor";
> > >                 reg = <0>;
> > > -               spi-max-frequency = <10000000>;
> > > +               spi-max-frequency = <50000000>;
> > >         };
> > >  };
> > > diff --git a/arch/arm64/boot/dts/rockchip/rk3399-rock-pi-4b.dts
> > > b/arch/arm64/boot/dts/rockchip/rk3399-rock-pi-4b.dts
> > > index bee6d7588..7122bf6c0 100644
> > > --- a/arch/arm64/boot/dts/rockchip/rk3399-rock-pi-4b.dts
> > > +++ b/arch/arm64/boot/dts/rockchip/rk3399-rock-pi-4b.dts
> > > @@ -37,7 +37,7 @@ &spi1 {
> > >         flash@0 {
> > >                 compatible = "jedec,spi-nor";
> > >                 reg = <0>;
> > > -               spi-max-frequency = <10000000>;
> > > +               spi-max-frequency = <50000000>;
> > >         };
> > >  };
> > > 
> > > diff --git a/arch/arm64/boot/dts/rockchip/rk3399-rock-pi-4c.dts
> > > b/arch/arm64/boot/dts/rockchip/rk3399-rock-pi-4c.dts
> > > index de2ebe4cb..8af75bc7c 100644
> > > --- a/arch/arm64/boot/dts/rockchip/rk3399-rock-pi-4c.dts
> > > +++ b/arch/arm64/boot/dts/rockchip/rk3399-rock-pi-4c.dts
> > > @@ -49,7 +49,7 @@ &spi1 {
> > >         flash@0 {
> > >                 compatible = "jedec,spi-nor";
> > >                 reg = <0>;
> > > -               spi-max-frequency = <10000000>;
> > > +               spi-max-frequency = <50000000>;
> > >         };
> > >  };
> > 
> > It would be better to upstream these changes to the Linux kernel
> > first, and then sync them back to U-Boot.
> 
> Oops, my bad, sorry, I got confused with your other patch on the U-
> Boot mailing list.
> 
> Regarding the new spi-max-frequency value, it should be better to
> have it set to what the SPI chip actually supports, and let the SPI
> driver do its thing.

OK, I agree. I'll send a v2 of this patch with a new spi-max-frequency
of 108 MHz.