From patchwork Thu Nov 9 22:20:53 2017 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Wolfram Sang X-Patchwork-Id: 836532 Return-Path: X-Original-To: incoming@patchwork.ozlabs.org Delivered-To: patchwork-incoming@bilbo.ozlabs.org Authentication-Results: ozlabs.org; spf=none (mailfrom) smtp.mailfrom=vger.kernel.org (client-ip=209.132.180.67; helo=vger.kernel.org; envelope-from=linux-i2c-owner@vger.kernel.org; receiver=) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by ozlabs.org (Postfix) with ESMTP id 3yXyL62sWfz9sPt for ; Fri, 10 Nov 2017 09:21:02 +1100 (AEDT) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754596AbdKIWVA (ORCPT ); Thu, 9 Nov 2017 17:21:00 -0500 Received: from sauhun.de ([88.99.104.3]:39654 "EHLO pokefinder.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753917AbdKIWVA (ORCPT ); Thu, 9 Nov 2017 17:21:00 -0500 Received: from localhost (p54B33A46.dip0.t-ipconnect.de [84.179.58.70]) by pokefinder.org (Postfix) with ESMTPSA id B19662C3468; Thu, 9 Nov 2017 23:20:57 +0100 (CET) From: Wolfram Sang To: linux-i2c@vger.kernel.org Cc: linux-renesas-soc@vger.kernel.org, Jacopo Mondi , Yoshihiro Shimoda , Wolfram Sang Subject: [RFT] i2c: sh_mobile: avoid unnecessary register read Date: Thu, 9 Nov 2017 23:20:53 +0100 Message-Id: <20171109222053.27093-1-wsa+renesas@sang-engineering.com> X-Mailer: git-send-email 2.11.0 Sender: linux-i2c-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-i2c@vger.kernel.org There is no data when the first WAIT interrupt arrives. No need to read something then. Signed-off-by: Wolfram Sang Tested-by: Jacopo Mondi --- I am not super happy with (real pos >= 0) done twice, but I didn't find a better solution yet. The compiler will make this cheap anyhow, I guess. Jacopo: can you please test this on top of all other patches? drivers/i2c/busses/i2c-sh_mobile.c | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-) diff --git a/drivers/i2c/busses/i2c-sh_mobile.c b/drivers/i2c/busses/i2c-sh_mobile.c index 80561ffbcf7b46..40a66d466c3c49 100644 --- a/drivers/i2c/busses/i2c-sh_mobile.c +++ b/drivers/i2c/busses/i2c-sh_mobile.c @@ -433,8 +433,9 @@ static int sh_mobile_i2c_isr_rx(struct sh_mobile_i2c_data *pd) break; } data = i2c_op(pd, OP_RX_STOP_DATA, 0); - } else + } else if (real_pos >= 0) { data = i2c_op(pd, OP_RX, 0); + } if (real_pos >= 0) pd->msg->buf[real_pos] = data;