From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1756302Ab2FNX6X (ORCPT ); Thu, 14 Jun 2012 19:58:23 -0400 Received: from mail-pb0-f46.google.com ([209.85.160.46]:56620 "EHLO mail-pb0-f46.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1755640Ab2FNX6S (ORCPT ); Thu, 14 Jun 2012 19:58:18 -0400 Message-Id: <20120614235645.255779542@linuxfoundation.org> User-Agent: quilt/0.60-20.1 Date: Thu, 14 Jun 2012 16:56:55 -0700 From: Greg KH To: linux-kernel@vger.kernel.org, stable@vger.kernel.org Cc: torvalds@linux-foundation.org, akpm@linux-foundation.org, alan@lxorguk.ukuu.org.uk, Andre Przywara , Andreas Herrmann , Guenter Roeck , Jean Delvare , Tim Gardner Subject: [ 11/20] hwmon: (fam15h_power) Increase output resolution In-Reply-To: <20120614235648.GA6552@kroah.com> Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 3.0-stable review patch. If anyone has any objections, please let me know. ------------------ From: Andre Przywara commit 941a956b0e387b21f385f486c34ef67576775cfc upstream. On high CPU load the accumulating values in the running_avg_cap register are very low (below 10), so averaging them too early leads to unnecessary poor output resolution. Since we pretend to output micro-Watt we better keep all the bits we have as long as possible. Signed-off-by: Andre Przywara Signed-off-by: Andreas Herrmann Acked-by: Guenter Roeck Signed-off-by: Jean Delvare Signed-off-by: Tim Gardner Signed-off-by: Greg Kroah-Hartman --- drivers/hwmon/fam15h_power.c | 8 ++++---- 1 file changed, 4 insertions(+), 4 deletions(-) --- a/drivers/hwmon/fam15h_power.c +++ b/drivers/hwmon/fam15h_power.c @@ -61,14 +61,14 @@ static ssize_t show_power(struct device REG_TDP_RUNNING_AVERAGE, &val); running_avg_capture = (val >> 4) & 0x3fffff; running_avg_capture = sign_extend32(running_avg_capture, 21); - running_avg_range = val & 0xf; + running_avg_range = (val & 0xf) + 1; pci_bus_read_config_dword(f4->bus, PCI_DEVFN(PCI_SLOT(f4->devfn), 5), REG_TDP_LIMIT3, &val); tdp_limit = val >> 16; - curr_pwr_watts = tdp_limit + data->base_tdp - - (s32)(running_avg_capture >> (running_avg_range + 1)); + curr_pwr_watts = (tdp_limit + data->base_tdp) << running_avg_range; + curr_pwr_watts -= running_avg_capture; curr_pwr_watts *= data->tdp_to_watts; /* @@ -78,7 +78,7 @@ static ssize_t show_power(struct device * scaling factor 1/(2^16). For conversion we use * (10^6)/(2^16) = 15625/(2^10) */ - curr_pwr_watts = (curr_pwr_watts * 15625) >> 10; + curr_pwr_watts = (curr_pwr_watts * 15625) >> (10 + running_avg_range); return sprintf(buf, "%u\n", (unsigned int) curr_pwr_watts); } static DEVICE_ATTR(power1_input, S_IRUGO, show_power, NULL);