The situation is similar to commit bf6376642fe8 ("board: ti: common: board_detect: Fix EEPROM read quirk"). This is seen on a variant of eeproms seen on some BeagleBone-AI64 which now has a mix of both 1 byte addressing and 2 byte addressing eeproms.
Unlike the am335x (ti_i2c_eeprom_am_get) and dra7 (ti_i2c_eeprom_dra7_get) which use constant data structure which allows us to do a complete read of the data, the am6(ti_i2c_eeprom_am6_get) eeprom parse operation is dynamic.
This removes the option of being able to read the complete eeprom data in one single shot.
Fortunately, on the I2C bus, we do see the following behavior: In 1 byte mode, if we attempt to read the first header data yet again, the misbehaving 2 byte addressing device acts in constant addressing mode which results in the header not matching up and follow on attempt at 2 byte addressing scheme grabs the correct data.
This costs us an extra ~3 milliseconds, which is a minor penalty compared to the consistent image support we need to have.
Reported-by: Jason Kridner jkridner@beagleboard.org Fixes: a58147c2dbbf ("board: ti: common: board_detect: Do 1byte address checks first.") Signed-off-by: Nishanth Menon nm@ti.com ---
BeagleBone-AI64 logs with this patch: With 1 byte addressing eeproms : https://www.irccloud.com/pastebin/XRjFVW82/ With quirky 2 byte addressing eeproms: https://www.irccloud.com/pastebin/eCQugpP6/
Wave capture of the quirky 2 byte addressing with this patch: https://pasteboard.co/bcNQyj3MVOpG.png
board/ti/common/board_detect.c | 9 +++++++++ 1 file changed, 9 insertions(+)
diff --git a/board/ti/common/board_detect.c b/board/ti/common/board_detect.c index 9fa7b7beb63f..b959041cd22f 100644 --- a/board/ti/common/board_detect.c +++ b/board/ti/common/board_detect.c @@ -444,6 +444,16 @@ int __maybe_unused ti_i2c_eeprom_am6_get(int bus_addr, int dev_addr, if (rc) return rc;
+ /* + * Handle case of bad 2 byte eeproms that responds to 1 byte addressing + * but gets stuck in const addressing when read requests are performed + * on offsets. We re-read the board ID to ensure we have sane data back + */ + rc = ti_i2c_eeprom_get(bus_addr, dev_addr, TI_EEPROM_HEADER_MAGIC, + sizeof(board_id), (uint8_t *)&board_id); + if (rc) + return rc; + if (board_id.header.id != TI_AM6_EEPROM_RECORD_BOARD_ID) { pr_err("%s: Invalid board ID record!\n", __func__); return -EINVAL;