From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752530Ab1CBFcd (ORCPT ); Wed, 2 Mar 2011 00:32:33 -0500 Received: from imr3.ericy.com ([198.24.6.13]:40343 "EHLO imr3.ericy.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751384Ab1CBFcb (ORCPT ); Wed, 2 Mar 2011 00:32:31 -0500 From: Guenter Roeck To: Jean Delvare CC: Jonathan Cameron , Randy Dunlap , Greg Schnorr , , , , Guenter Roeck Subject: [PATCH] hwmon: (pmbus) More stringent checking of VOUT_MODE register Date: Tue, 1 Mar 2011 21:32:20 -0800 Message-ID: <1299043940-22798-1-git-send-email-guenter.roeck@ericsson.com> X-Mailer: git-send-email 1.7.3.1 MIME-Version: 1.0 Content-Type: text/plain Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Some PMBus chips do not support the VOUT_MODE register. To make matters worse, such chips may not return an error when reading the register either, but instead return 0xff. Check if the register exists using pmbus_check_byte_register() before reading its value. In addition, validate the returned value and ignore it if it is 0xff (which is invalid). Reported-by: Greg Schnorr Signed-off-by: Guenter Roeck --- drivers/hwmon/pmbus_core.c | 7 ++++--- 1 files changed, 4 insertions(+), 3 deletions(-) diff --git a/drivers/hwmon/pmbus_core.c b/drivers/hwmon/pmbus_core.c index 0edab1c..b7c64ba 100644 --- a/drivers/hwmon/pmbus_core.c +++ b/drivers/hwmon/pmbus_core.c @@ -1426,10 +1426,11 @@ static void pmbus_find_attributes(struct i2c_client *client, static int pmbus_identify_common(struct i2c_client *client, struct pmbus_data *data) { - int vout_mode, exponent; + int vout_mode = -1, exponent; - vout_mode = pmbus_read_byte_data(client, 0, PMBUS_VOUT_MODE); - if (vout_mode >= 0) { + if (pmbus_check_byte_register(client, 0, PMBUS_VOUT_MODE)) + vout_mode = pmbus_read_byte_data(client, 0, PMBUS_VOUT_MODE); + if (vout_mode >= 0 && vout_mode != 0xff) { /* * Not all chips support the VOUT_MODE command, * so a failure to read it is not an error. -- 1.7.3.1