Re: [PATCH 2/5] ARM: dts: at91: sam9x60-curiosity: Fix EEPROM type

[Eugen Hristev <eugen.hristev@collabora.com>]

On 7/6/23 11:06, Eugen Hristev wrote:
> On 7/5/23 23:16, Alexander Dahl wrote:
>> From: Alexander Dahl <ada@thorsis.com>
>>
>> The user guide says it's a Microchip 24AA025E48 serial EEPROM, which is
>> a 2-Kbit I2C Serial EEPROM with EUI-48™ Identity.  This is the chip
>> actually populated on board EV40E67A rev 4.
>>
>> Signed-off-by: Alexander Dahl <ada@thorsis.com>
>> ---
>>
>> Notes:
>>      Sadly this did not fix the problem, that I could not access that
>>      eeprom through I²C.
>>
>>   arch/arm/dts/at91-sam9x60_curiosity.dts | 2 +-
>>   1 file changed, 1 insertion(+), 1 deletion(-)
>>
>> diff --git a/arch/arm/dts/at91-sam9x60_curiosity.dts 
>> b/arch/arm/dts/at91-sam9x60_curiosity.dts
>> index d6ae3d648d..da5e19b66b 100644
>> --- a/arch/arm/dts/at91-sam9x60_curiosity.dts
>> +++ b/arch/arm/dts/at91-sam9x60_curiosity.dts
>> @@ -31,7 +31,7 @@
>>                       status = "okay";
>>                       eeprom@53 {
>> -                        compatible = "atmel,24c32";
>> +                        compatible = "atmel,24c02";
>>                           reg = <0x53>;
>>                           pagesize = <16>;
>>                       };
> 
> Hello Alexander,
> 
> Thank you for the patch.
> 
> I remember I tested this a while back and I remember that the 24c32 
> compatible is not correct for this eeprom.
> 
> I have this commit that fixed it for sam9x60ek board:
> 
> commit 5ae89b3cfe842ecbb5153a95e2e3ac404abe543c
> Author: Eugen Hristev <eugen.hristev@collabora.com>
> Date:   Thu May 26 17:04:56 2022 +0300
> 
>      ARM: dts: at91: sam9x60ek: fix eeprom compatible
> 
> 
> 
> 24c32 should be 32K and 24c02 is 2K .
> 
> I remember that with 24c32 it works, but when you read , the offset 
> changes, and then you read the same data multiple times, as if the 2K is 
> multiplied to have the 32K the driver thinks it has.
> 
> Do you have any reasoning for wanting to change the compatible to 24c32 ?
> I am trying to understand how you found that 24c32 is better.
> 
> Eugen
> 

I am sorry, I misread your patch. You are doing the exact opposite, 
which appears to be correct ! Ignore the noise.