Return-path: Received: from arrakis.dune.hu ([78.24.191.176]:55335 "EHLO arrakis.dune.hu" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754656Ab3HPWeD (ORCPT ); Fri, 16 Aug 2013 18:34:03 -0400 From: Gabor Juhos To: "John W. Linville" Cc: linux-wireless@vger.kernel.org, users@rt2x00.serialmonkey.com, Gabor Juhos Subject: [PATCH 2/5] rt2x00: rt2800lib: optimize frequency offset adjustment Date: Fri, 16 Aug 2013 22:38:15 +0200 Message-Id: <1376685498-5167-3-git-send-email-juhosg@openwrt.org> (sfid-20130817_003415_735726_4AE60911) In-Reply-To: <1376685498-5167-1-git-send-email-juhosg@openwrt.org> References: <1376685498-5167-1-git-send-email-juhosg@openwrt.org> Sender: linux-wireless-owner@vger.kernel.org List-ID: Don't write the new value into the register if it is the same as the old value to avoid unncessary USB bus traffic with USB devices. The change also saves a few cycle on MMIO based devices. Based on the DPO_RT5572_LinuxSTA_2.6.0.1_20120629 driver. Reference: RTMPAdjustFrequencyOffset function in common/rt_rf.c Signed-off-by: Gabor Juhos --- drivers/net/wireless/rt2x00/rt2800lib.c | 6 +++++- 1 file changed, 5 insertions(+), 1 deletion(-) diff --git a/drivers/net/wireless/rt2x00/rt2800lib.c b/drivers/net/wireless/rt2x00/rt2800lib.c index d4e6dea..c990a27 100644 --- a/drivers/net/wireless/rt2x00/rt2800lib.c +++ b/drivers/net/wireless/rt2x00/rt2800lib.c @@ -2495,13 +2495,17 @@ static void rt2800_config_channel_rf3053(struct rt2x00_dev *rt2x00dev, static void rt2800_adjust_freq_offset(struct rt2x00_dev *rt2x00dev) { u8 freq_offset; - u8 rfcsr; + u8 rfcsr, prev_rfcsr; freq_offset = rt2x00_get_field8(rt2x00dev->freq_offset, RFCSR17_CODE); freq_offset = min_t(u8, freq_offset, FREQ_OFFSET_BOUND); rt2800_rfcsr_read(rt2x00dev, 17, &rfcsr); + prev_rfcsr = rfcsr; rt2x00_set_field8(&rfcsr, RFCSR17_CODE, freq_offset); + if (rfcsr == prev_rfcsr) + return; + rt2800_rfcsr_write(rt2x00dev, 17, rfcsr); } -- 1.7.10