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

From: <Tudor.Ambarus@microchip.com>
To: <boris.brezillon@bootlin.com>
Cc: <Nicolas.Ferre@microchip.com>, <alexandre.belloni@bootlin.com>,
	<Ludovic.Desroches@microchip.com>, <robh+dt@kernel.org>,
	<mark.rutland@arm.com>, <Cyrille.Pitchen@microchip.com>,
	<linux-arm-kernel@lists.infradead.org>,
	<devicetree@vger.kernel.org>, <linux-kernel@vger.kernel.org>,
	<linux-mtd@lists.infradead.org>, <broonie@kernel.org>,
	<linux-spi@vger.kernel.org>
Subject: Re: [PATCH] ARM: dts: at91: sama5d2 Xplained: add QSPI0 + SPI NOR memory nodes
Date: Tue, 11 Dec 2018 14:49:44 +0000	[thread overview]
Message-ID: <6e2aa831-dc12-8431-d089-10f35cec4cd6@microchip.com> (raw)
In-Reply-To: <20181211154033.076506aa@bbrezillon>

Hi, Boris,

On 12/11/2018 04:40 PM, Boris Brezillon wrote:
> On Mon, 10 Dec 2018 17:15:29 +0000
> <Tudor.Ambarus@microchip.com> wrote:
> 
>> From: Cyrille Pitchen <cyrille.pitchen@microchip.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@microchip.com>
>> [tudor.ambarus@microchip.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@microchip.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@f0020000 {
>> +				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