[PATCH v2] misc: i2c_eeprom: implement different probe test eeprom offset

[Eugen.Hristev at microchip.com]

On 07.05.2020 18:02, Baruch Siach wrote:
> Hi Heiko,
> 
> On Thu, May 07 2020, Heiko Schocher wrote:
>> Am 07.05.2020 um 10:53 schrieb Eugen Hristev:
>>> Because of this commit :
>>> 5ae84860b0 ("misc: i2c_eeprom: verify that the chip is functional at probe()")
>>> at probe time, each eeprom is tested for read at offset 0.
>>>
>>> The Atmel AT24MAC402 eeprom has different mapping. One i2c slave address is
>>> used for the lower 0x80 bytes and another i2c slave address is used for the
>>> upper 0x80 bytes. Because of this basically the i2c master sees 2 different
>>> slaves. We need the upper bytes because we read the unique MAC address from
>>> this EEPROM area.
>>>
>>> However this implies that our slave address will return error on reads
>>> from address 0x0 to 0x80.
>>>
>>> To solve this, implemented an offset field inside platform data that is by
>>> default 0 (as it is used now), but can be changed in the compatible table.
>>>
>>> The probe function will now read at this offset and use it, instead of blindly
>>> checking offset 0.
>>>
>>> This will fix the regression noticed on these EEPROMs since the commit
>>> abovementioned that introduces the probe failed issue.
>>>
>>> Signed-off-by: Eugen Hristev <eugen.hristev at microchip.com>
>>> ---
>>>
>>> Please disregard patch
>>> [PATCH] misc: i2c_eeprom: implement different probe test eeprom offset
>>>
>>> as that patch was mistakenly done on an older u-boot version.
>>> This v2 patch applies correctly on u-boot/master
>>>
>>> Changes in v2:
>>> - adapt to latest changes in driver. v1 was done on u-boot 2020.01 accidentaly.
>>>
>>>    drivers/misc/i2c_eeprom.c | 8 +++++++-
>>>    1 file changed, 7 insertions(+), 1 deletion(-)
>>
>> Thanks for rebasing!
>>
>> I prefer to fix the issue instead reverting commit:
>>
>> 5ae84860b0 ("misc: i2c_eeprom: verify that the chip is functional at probe()")
>>
>> Reviewed-by: Heiko Schocher <hs at denx.de>
>>
>> @Baruch, is this Ok for you?
> 
> According to the Linux driver there are more devices that need read
> offset. 24cs32 and 24cs64 are affected. This patch does not fix the
> regression for those devices.
> 
> Eugen, would it be possible for you to extend the fix to 24cs32/64 and
> test on real hardware?

Hi Baruch,

This patch fixes my issue at hand and the eeprom which I have at my 
disposal. I will look to see if I have those, but, most likely not.
I can extend the fix, but I cannot test, so, I rather not go blind with it.

Eugen
> 
> baruch
> 
>>> diff --git a/drivers/misc/i2c_eeprom.c b/drivers/misc/i2c_eeprom.c
>>> index ef5f103c98..32a1b20856 100644
>>> --- a/drivers/misc/i2c_eeprom.c
>>> +++ b/drivers/misc/i2c_eeprom.c
>>> @@ -17,6 +17,7 @@ struct i2c_eeprom_drv_data {
>>>       u32 pagesize; /* page size in bytes */
>>>       u32 addr_offset_mask; /* bits in addr used for offset overflow */
>>>       u32 offset_len; /* size in bytes of offset */
>>> +    u32 start_offset; /* valid start offset inside memory, by default 0 */
>>>    };
>>>      int i2c_eeprom_read(struct udevice *dev, int offset, uint8_t *buf, int
>>> size)
>>> @@ -147,7 +148,11 @@ static int i2c_eeprom_std_probe(struct udevice *dev)
>>>       i2c_set_chip_addr_offset_mask(dev, data->addr_offset_mask);
>>>       /* Verify that the chip is functional */
>>> -    ret = i2c_eeprom_read(dev, 0, &test_byte, 1);
>>> +    /*
>>> +     * Not all eeproms start from offset 0. Valid offset is available
>>> +     * in the platform data struct.
>>> +     */
>>> +    ret = i2c_eeprom_read(dev, data->start_offset, &test_byte, 1);
>>>       if (ret)
>>>               return -ENODEV;
>>>    @@ -215,6 +220,7 @@ static const struct i2c_eeprom_drv_data
>>> atmel24mac402_data = {
>>>       .pagesize = 16,
>>>       .addr_offset_mask = 0,
>>>       .offset_len = 1,
>>> +    .start_offset = 0x80,
>>>    };
>>>      static const struct i2c_eeprom_drv_data atmel24c32_data = {
>>>
> 
> 
> --
>                                                       ~. .~   Tk Open Systems
> =}------------------------------------------------ooO--U--Ooo------------{=
>     - baruch at tkos.co.il - tel: +972.52.368.4656, http://www.tkos.co.il -
>