From patchwork Fri Dec 16 20:06:11 2016 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: "Russell King (Oracle)" X-Patchwork-Id: 9478475 Return-Path: Received: from mail.wl.linuxfoundation.org (pdx-wl-mail.web.codeaurora.org [172.30.200.125]) by pdx-korg-patchwork.web.codeaurora.org (Postfix) with ESMTP id A2EA1601C2 for ; Fri, 16 Dec 2016 20:08:48 +0000 (UTC) Received: from mail.wl.linuxfoundation.org (localhost [127.0.0.1]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id 95B6128766 for ; Fri, 16 Dec 2016 20:08:48 +0000 (UTC) Received: by mail.wl.linuxfoundation.org (Postfix, from userid 486) id 88E1E28782; Fri, 16 Dec 2016 20:08:48 +0000 (UTC) X-Spam-Checker-Version: SpamAssassin 3.3.1 (2010-03-16) on pdx-wl-mail.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-4.1 required=2.0 tests=BAYES_00,DKIM_SIGNED, RCVD_IN_DNSWL_MED,T_DKIM_INVALID autolearn=ham version=3.3.1 Received: from bombadil.infradead.org (bombadil.infradead.org [198.137.202.9]) (using TLSv1.2 with cipher AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by mail.wl.linuxfoundation.org (Postfix) with ESMTPS id 7908F28766 for ; Fri, 16 Dec 2016 20:08:46 +0000 (UTC) Received: from localhost ([127.0.0.1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.85_2 #1 (Red Hat Linux)) id 1cHymK-0006ha-C1; Fri, 16 Dec 2016 20:06:52 +0000 Received: from pandora.armlinux.org.uk ([2001:4d48:ad52:3201:214:fdff:fe10:1be6]) by bombadil.infradead.org with esmtps (Exim 4.85_2 #1 (Red Hat Linux)) id 1cHymD-0006cY-9m for linux-arm-kernel@lists.infradead.org; Fri, 16 Dec 2016 20:06:46 +0000 DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=armlinux.org.uk; s=pandora-2014; h=Date:Sender:Message-Id:Content-Type:Content-Transfer-Encoding:MIME-Version:Subject:Cc:To:From; bh=+vRmx1FbSDjEa8MRr0oEQt6gYcVmzE47iWUlhDWA2mc=; b=JrWKnk0dXGtkE2WKGTkiVr7PXolgSrnPcnCXkGsJBvroCSILze1YSfoyOY/MLawv12dkSrzLs1Cg2TBNWVwPod+XkwbFQQTWWYSlOHR7lxQlWTqz/rp7sYv2CC0MFYC9Sg1+ospUF6dzoVyhbNoaQi/LVst/ZDUr6TD/mruZ6U8=; Received: from e0022681537dd.dyn.armlinux.org.uk ([2001:4d48:ad52:3201:222:68ff:fe15:37dd]:47252 helo=rmk-PC.armlinux.org.uk) by pandora.armlinux.org.uk with esmtpsa (TLSv1:AES128-SHA:128) (Exim 4.82_1-5b7a7c0-XX) (envelope-from ) id 1cHylg-0001yc-KW; Fri, 16 Dec 2016 20:06:12 +0000 Received: from rmk by rmk-PC.armlinux.org.uk with local (Exim 4.82_1-5b7a7c0-XX) (envelope-from ) id 1cHylf-00071o-KZ; Fri, 16 Dec 2016 20:06:11 +0000 From: Russell King To: Peter Rosin Subject: [PATCH] i2c: mux: pca954x: fix i2c mux selection caching MIME-Version: 1.0 Content-Disposition: inline Message-Id: Date: Fri, 16 Dec 2016 20:06:11 +0000 X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20161216_120645_812215_1E462C28 X-CRM114-Status: GOOD ( 11.71 ) X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.20 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: linux-i2c@vger.kernel.org, linux-arm-kernel@lists.infradead.org, Wolfram Sang Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+patchwork-linux-arm=patchwork.kernel.org@lists.infradead.org X-Virus-Scanned: ClamAV using ClamSMTP smbus functions return -ve on error, 0 on success. However, __i2c_transfer() have a different return signature - -ve on error, or number of buffers transferred (which may be zero or greater.) The upshot of this is that the sense of the test is reversed when using the mux on a bus supporting the master_xfer method: we cache the value and never retry if we fail to transfer any buffers, but if we succeed, we clear the cached value. Fix this. Fixes: 463e8f845cbf ("i2c: mux: pca954x: retry updating the mux selection on failure") Signed-off-by: Russell King --- drivers/i2c/muxes/i2c-mux-pca954x.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/drivers/i2c/muxes/i2c-mux-pca954x.c b/drivers/i2c/muxes/i2c-mux-pca954x.c index 8bc3d36d2837..b6d62ecbd5b6 100644 --- a/drivers/i2c/muxes/i2c-mux-pca954x.c +++ b/drivers/i2c/muxes/i2c-mux-pca954x.c @@ -179,7 +179,7 @@ static int pca954x_select_chan(struct i2c_mux_core *muxc, u32 chan) /* Only select the channel if its different from the last channel */ if (data->last_chan != regval) { ret = pca954x_reg_write(muxc->parent, client, regval); - data->last_chan = ret ? 0 : regval; + data->last_chan = ret >= 0 ? regval : 0; } return ret;