From: Romain Izard <romain.izard.pro@gmail.com>
To: Alexandre Belloni <alexandre.belloni@bootlin.com>
Cc: Nicolas Ferre <nicolas.ferre@microchip.com>,
Tudor Ambarus <Tudor.Ambarus@microchip.com>,
Rob Herring <robh+dt@kernel.org>,
mark.rutland@arm.com,
linux-arm-kernel <linux-arm-kernel@lists.infradead.org>,
devicetree@vger.kernel.org, LKML <linux-kernel@vger.kernel.org>
Subject: Re: [PATCH] ARM: dts: at91: sama5d2: use the divided clock for SMC
Date: Tue, 20 Nov 2018 19:01:32 +0100 [thread overview]
Message-ID: <CAGkQfmPHRKqMvm6bNDf8S5qM7uE5T-izij=jm2nob0zrOgOM-w@mail.gmail.com> (raw)
In-Reply-To: <20181120171612.GF8367@piout.net>
Le mar. 20 nov. 2018 à 18:16, Alexandre Belloni
<alexandre.belloni@bootlin.com> a écrit :
>
> Hello Romain,
>
> On 20/11/2018 17:57:37+0100, Romain Izard wrote:
> > The SAMA5D2 is different from SAMA5D3 and SAMA5D4, as there are two
> > different clocks for the peripherals in the SoC. The Static Memory
> > controller is connected to the divided master clock.
> >
> > Unfortunately, the device tree does not correctly show this and uses the
> > master clock directly. This clock is then used by the code for the NAND
> > controller to calculate the timings for the controller, and we end up with
> > slow NAND Flash access.
> >
> > Fix the device tree, and the performance of Flash access is improved.
> >
> > Signed-off-by: Romain Izard <romain.izard.pro@gmail.com>
> > ---
> > arch/arm/boot/dts/sama5d2.dtsi | 2 +-
> > 1 file changed, 1 insertion(+), 1 deletion(-)
> >
> > diff --git a/arch/arm/boot/dts/sama5d2.dtsi b/arch/arm/boot/dts/sama5d2.dtsi
> > index 61f68e5c48e9..b405992eb601 100644
> > --- a/arch/arm/boot/dts/sama5d2.dtsi
> > +++ b/arch/arm/boot/dts/sama5d2.dtsi
> > @@ -308,7 +308,7 @@
> > 0x1 0x0 0x60000000 0x10000000
> > 0x2 0x0 0x70000000 0x10000000
> > 0x3 0x0 0x80000000 0x10000000>;
> > - clocks = <&mck>;
> > + clocks = <&h32ck>;
>
> You will have to rebase on top of at91-dt. And if I'm not mistaken, this
> line should be:
>
> + clocks = <&pmc PMC_TYPE_CORE PMC_MCK2>;
>
> > status = "disabled";
> >
> > nand_controller: nand-controller {
I guess you're right but this will only reach mainline in 4.21. I get slow
flash access with 4.19 as well...
After a second look, it looks like the SAMA5D4 is affected too.
Best regards,
--
Romain Izard
next prev parent reply other threads:[~2018-11-20 18:01 UTC|newest]
Thread overview: 5+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-11-20 16:57 [PATCH] ARM: dts: at91: sama5d2: use the divided clock for SMC Romain Izard
2018-11-20 17:16 ` Alexandre Belloni
2018-11-20 18:01 ` Romain Izard [this message]
2018-11-20 20:40 ` Alexandre Belloni
2018-11-21 11:00 ` Alexandre Belloni
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