linux-kernel - Re: [PATCH] ARM: dts: at91: sama5d2 Xplained: add QSPI0 + SPI NOR memory nodes

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Message-ID: <6e2aa831-dc12-8431-d089-10f35cec4cd6@microchip.com>
Date:   Tue, 11 Dec 2018 14:49:44 +0000
From:   <Tudor.Ambarus@...rochip.com>
To:     <boris.brezillon@...tlin.com>
CC:     <Nicolas.Ferre@...rochip.com>, <alexandre.belloni@...tlin.com>,
        <Ludovic.Desroches@...rochip.com>, <robh+dt@...nel.org>,
        <mark.rutland@....com>, <Cyrille.Pitchen@...rochip.com>,
        <linux-arm-kernel@...ts.infradead.org>,
        <devicetree@...r.kernel.org>, <linux-kernel@...r.kernel.org>,
        <linux-mtd@...ts.infradead.org>, <broonie@...nel.org>,
        <linux-spi@...r.kernel.org>
Subject: Re: [PATCH] ARM: dts: at91: sama5d2 Xplained: add QSPI0 + SPI NOR
 memory nodes

Hi, Boris,

On 12/11/2018 04:40 PM, Boris Brezillon wrote:
> On Mon, 10 Dec 2018 17:15:29 +0000
> <Tudor.Ambarus@...rochip.com> wrote:
> 
>> From: Cyrille Pitchen <cyrille.pitchen@...rochip.com>
>>
>> This patch configures the QSPI0 controller pin muxing and declares
>> a jedec,spi-nor memory.
>>
>> sama5d2 Xplained RevB and RevC use the Macronix MX25L25673G flash
>> memory which advertises a maximum frequency of 80MHz for Quad IO
>> Fast Read. Set the spi-max-frequency to 80MHz knowing that actually
>> the QSPI drver will set the SPI bus clock to 166MHz / 3 = 55.3MHz.

s/drver/driver

>>
>> Signed-off-by: Cyrille Pitchen <cyrille.pitchen@...rochip.com>
>> [tudor.ambarus@...rochip.com:
>> - drop partitions,
>> - add spi-rx/tx-bus-width
>> - change spi-max-frequency to match the 80MHz limit advertised by
>>   MX25L25673G for Quad IO Fast Read,
>> - reword commit message and subject.]
>> Signed-off-by: Tudor Ambarus <tudor.ambarus@...rochip.com>
>> ---
>>  arch/arm/boot/dts/at91-sama5d2_xplained.dts | 31 +++++++++++++++++++++++++++++
>>  1 file changed, 31 insertions(+)
>>
>> diff --git a/arch/arm/boot/dts/at91-sama5d2_xplained.dts b/arch/arm/boot/dts/at91-sama5d2_xplained.dts
>> index 518e2b095ccf..171bc82cfbbf 100644
>> --- a/arch/arm/boot/dts/at91-sama5d2_xplained.dts
>> +++ b/arch/arm/boot/dts/at91-sama5d2_xplained.dts
>> @@ -108,6 +108,21 @@
>>  		};
>>  
>>  		apb {
>> +			qspi0: spi@...20000 {
>> +				pinctrl-names = "default";
>> +				pinctrl-0 = <&pinctrl_qspi0_default>;
>> +				/* status = "okay"; */ /* conflict with sdmmc1 */
>> +
>> +				flash@0 {
>> +					compatible = "jedec,spi-nor";
>> +					reg = <0>;
>> +					spi-max-frequency = <80000000>;
>> +					spi-tx-bus-width = <4>;
>> +					spi-rx-bus-width = <4>;
>> +					m25p,fast-read;
>> +				};
> 
> I'm a bit lost. What's the point of defining this if the QSPI
> controller is not enabled?

You can enable qspi if you disable sdmmc1. I thought of having all described
together and choose one or another depending on needs.

ta