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From:   <Tudor.Ambarus@microchip.com>
To:     <Nicolas.Ferre@microchip.com>, <alexandre.belloni@bootlin.com>,
        <Ludovic.Desroches@microchip.com>
CC:     <robh+dt@kernel.org>, <devicetree@vger.kernel.org>,
        <linux-arm-kernel@lists.infradead.org>,
        <linux-kernel@vger.kernel.org>
Subject: Re: [PATCH] ARM: dts: at91: sama5d4_xplained: Mark optional
 AT25DF321A as disabled
Thread-Topic: [PATCH] ARM: dts: at91: sama5d4_xplained: Mark optional
 AT25DF321A as disabled
Thread-Index: AQHXaQy7ADHbvMwdrUWX0CVnQw3iqw==
Date:   Thu, 24 Jun 2021 15:22:24 +0000
Message-ID: <f8fcace3-fc18-ff3a-8d85-0fc10f672d5e@microchip.com>
References: <20210622134222.107806-1-tudor.ambarus@microchip.com>
 <4d631b4c-7d0c-3a04-5ab6-00d09c792438@microchip.com>
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On 6/22/21 4:53 PM, Nicolas Ferre wrote:
> Hi Tudor,
>=20
> On 22/06/2021 at 15:42, Tudor Ambarus wrote:
>> sama5d4_xplained has an optional on-board serial DataFlash (AT25DF321A),
>> which does not come populated on board by default. Mark it as disabled
>> to avoid the following probe error:
>> spi-nor spi0.0: unrecognized JEDEC id bytes: 00 00 00 00 00 00
>>
>> Signed-off-by: Tudor Ambarus <tudor.ambarus@microchip.com>
>> ---
>> =A0 arch/arm/boot/dts/at91-sama5d4_xplained.dts | 2 +-
>> =A0 1 file changed, 1 insertion(+), 1 deletion(-)
>>
>> diff --git a/arch/arm/boot/dts/at91-sama5d4_xplained.dts b/arch/arm/boot=
/dts/at91-sama5d4_xplained.dts
>> index 0b3ad1b580b8..f397e2a68e5c 100644
>> --- a/arch/arm/boot/dts/at91-sama5d4_xplained.dts
>> +++ b/arch/arm/boot/dts/at91-sama5d4_xplained.dts
>> @@ -40,7 +40,7 @@ uart0: serial@f8004000 {
>> =A0 =A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0 spi0: spi@f8010000 {
>> =A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0 cs-gpios =3D <&pioC =
3 0>, <0>, <0>, <0>;
>> -=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0 status =3D "okay";
>> +=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0 status =3D "disabled";
>> =A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0 m25p80@0 {
>> =A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0 compatib=
le =3D "atmel,at25df321a";
>> =A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0 spi-max-=
frequency =3D <50000000>;
>=20
> What about keeping SPI enabled and just having the status of m25p80 as di=
sabled: honestly, I don't know if it works and if it's desirable, but might=
 be closer to reality.
>=20
> Tell me what you think.

I think it will work, because child status is checked with __of_device_is_a=
vailable,
and the child will be skipped when marked as disabled.

But I feel that spi0 was enabled just because at25df321a was assumed to be =
populated.
Wouldn't it be strange to have spi0 marked as okay, but the only child as d=
isabled?
How about removing spi0 node entirely from sama5d4_xplained dts?

Cheers,
ta