[RFC PATCH] board: ti: common: board_detect: Fix EEPROM read quirk for 2-byte

[Neha Malcom Francis]

Hi Tom

On 29/11/22 19:01, Tom Rini wrote:
> On Tue, Nov 29, 2022 at 03:10:12PM +0300, Matwey V. Kornilov wrote:
>> вт, 29 нояб. 2022 г. в 09:50, Neha Malcom Francis <n-francis at ti.com>:
>>>
>>> EEPROM detection logic in ti_i2c_eeprom_get() involves figuring out
>>> whether addressing is 1-byte or 2-byte. There are currently different
>>> behaviours seen across boards as documented in commit bf6376642fe8
>>> ("board: ti: common: board_detect: Fix EEPROM read quirk"). Adding to
>>> the list, we see that there are 2-byte EEPROMs that read properly
>>> with 1-byte addressing with no offset.
>>>
>>> For ti_i2c_eeprom_am6_get where eeprom parse operation is dynamic, the
>>> earlier commit d2ab2a2bafd5 ("board: ti: common: board_detect: Fix
>>> EEPROM read quirk for AM6 style data") tried to resolve this by running
>>> ti_i2c_eeprom_get() twice. However this commit along with its former
>>> commit fails on J7 platforms where EEPROM successfully return back the
>>> header on 1-byte addressing and continues to do so until an offset is
>>> introduced. So the second read incorrectly determines the EEPROM as
>>> 1-byte addressing.
>>>
>>> A more generic solution is introduced here to solve
>>> this issue: 1-byte read without offset and 1-byte read with offset. If
>>> both passes, it follows 1-byte addressing else we proceed with 2-byte
>>> addressing check.
>>>
>>> Tested on J721E, J7200, DRA7xx, AM64x
>>
>> I'll try to test this on the AM335x boards I have as soon as possible.
> 
> I wonder if we should re-factor this code a bit and not have a single
> ti_i2c_eeprom_get but instead build for whichever sets of quirks a given
> family of boards has with their EEPROMs. I really worry that we're going
> to find that this change here breaks yet another different EEPROM than
> before.
> 

Yes that does make sense... considering a new behavior of EEPROM keeps 
showing up. I will try refactoring the logic that way.

-- 
Thanking You
Neha Malcom Francis