From 31641e34e8a3da5735d3cc901fb986bf6df28b6f Mon Sep 17 00:00:00 2001 From: Jean Delvare Date: Mon, 6 May 2019 15:16:56 +0200 Subject: [PATCH] eeprom: ee1004: Deal with nack on page selection Some EE1004 implementations will not properly ack page selection commands. They still set the page correctly, so there is no actual error. Deal with this case gracefully by checking the currently selected page after we receive a nack. If the page is set right then we can continue. Signed-off-by: Jean Delvare Tested-by: Jarkko Nikula Cc: Arnd Bergmann Cc: Greg Kroah-Hartman Signed-off-by: Greg Kroah-Hartman --- drivers/misc/eeprom/ee1004.c | 12 +++++++++++- 1 file changed, 11 insertions(+), 1 deletion(-) diff --git a/drivers/misc/eeprom/ee1004.c b/drivers/misc/eeprom/ee1004.c index 6c6348f..89abfa7 100644 --- a/drivers/misc/eeprom/ee1004.c +++ b/drivers/misc/eeprom/ee1004.c @@ -1,7 +1,7 @@ /* * ee1004 - driver for DDR4 SPD EEPROMs * - * Copyright (C) 2017 Jean Delvare + * Copyright (C) 2017-2019 Jean Delvare * * Based on the at24 driver: * Copyright (C) 2005-2007 David Brownell @@ -124,6 +124,16 @@ static ssize_t ee1004_read(struct file *filp, struct kobject *kobj, /* Data is ignored */ status = i2c_smbus_write_byte(ee1004_set_page[page], 0x00); + if (status == -ENXIO) { + /* + * Don't give up just yet. Some memory + * modules will select the page but not + * ack the command. Check which page is + * selected now. + */ + if (ee1004_get_current_page() == page) + status = 0; + } if (status < 0) { dev_err(dev, "Failed to select page %d (%d)\n", page, status); -- 2.7.4