[PATCH v2] board: ti: common: board_detect: Fix EEPROM offset read for 1-byte

[Nishanth Menon]

On 17:54-20231026, Prasanth Babu Mantena wrote:
> EEPROM detection logic in ti_i2c_eeprom_get() involves reading the total
> size followed by reading 1-byte size with an offset 1. This commit fixes
> the header matching issue in commit 9f393a2d7af8 ("board: ti: common:
> board_detect: Fix EEPROM read quirk for 2-byte").
> 
> In the previous commit, the value with one offset is being read into
> offset_test, but the pointer used to match was still ep. ep is the
> pointer where previously read data is stored, resulting in an invalid
> comparision of the values. The intent is to identify bad 2-byte
> addressing eerpoms, which respond to the initial 1-byte addressing
> request and gets stuck on the succesive reads. After successive read
> with an offset 1, the 1-byte data is compared with the second byte of
> the header to ensure it as a valid 1byte addressing eeprom.
> This is taken care by comparing proper first byte value from, header
> with an offset 1 byte, to offset_test having the 1-byte data read from eeprom.

Rephrase (I at times go to grammarly.com to make sure I use the right
verbage): So, keep it simple (we can read code - no need to give us the
detail readup). Stuff like "in the previous commit" leaves us wondering
which commit.

EEPROM detection logic in ti_i2c_eeprom_get() involves reading the total
size followed by reading 1-byte size with an offset 1.
The commit 9f393a2d7af8 ("board: ti: common: board_detect: Fix EEPROM
read quirk for 2-byte") that attempts to fix this uses the wrong pointer to
to compare.

> 
> Fixes: 9f393a2d7af8 (board: ti: common: board_detect: Fix EEPROM read quirk for 2-byte)
> Signed-off-by: Prasanth Babu Mantena <p-mantena at ti.com>
> ---
> v2 <--> v1:
> Fix inplace for the else condition of CONFIG_IS_ENABLED(DM_I2C).
> Improved commit message.
> 
>  board/ti/common/board_detect.c | 4 ++--
>  1 file changed, 2 insertions(+), 2 deletions(-)
> 
> diff --git a/board/ti/common/board_detect.c b/board/ti/common/board_detect.c
> index 9a53884c98..869f7a47f8 100644
> --- a/board/ti/common/board_detect.c
> +++ b/board/ti/common/board_detect.c
> @@ -128,7 +128,7 @@ static int __maybe_unused ti_i2c_eeprom_get(int bus_addr, int dev_addr,
>  
>  	rc = dm_i2c_read(dev, 0x1, &offset_test, sizeof(offset_test));
>  
> -	if (*((u32 *)ep) != (header & 0xFF))
> +	if (offset_test != ((header >> 8) & 0xFF))
>  		one_byte_addressing = false;
>  
>  	/* Corrupted data??? */
> @@ -180,7 +180,7 @@ static int __maybe_unused ti_i2c_eeprom_get(int bus_addr, int dev_addr,
>  
>  	rc = i2c_read(dev_addr, 0x1, byte, &offset_test, sizeof(offset_test));
>  
> -	if (*((u32 *)ep) != (header & 0xFF))
> +	if (offset_test != ((header >> 8) & 0xFF))
>  		one_byte_addressing = false;
>  
>  	/* Corrupted data??? */
> -- 
> 2.39.0
> 

-- 
Regards,
Nishanth Menon
Key (0xDDB5849D1736249D) / Fingerprint: F8A2 8693 54EB 8232 17A3  1A34 DDB5 849D 1736 249D