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[23.128.96.18]) by mx.google.com with ESMTP id dn28si2274480edb.195.2020.06.25.00.42.21; Thu, 25 Jun 2020 00:42:44 -0700 (PDT) Received-SPF: pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 23.128.96.18 as permitted sender) client-ip=23.128.96.18; Authentication-Results: mx.google.com; dkim=pass header.i=@gorani.run header.s=MBO0001 header.b=n08L3MBT; spf=pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 23.128.96.18 as permitted sender) smtp.mailfrom=linux-kernel-owner@vger.kernel.org; dmarc=pass (p=NONE sp=NONE dis=NONE) header.from=gorani.run Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S2390403AbgFYHlp (ORCPT + 99 others); Thu, 25 Jun 2020 03:41:45 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:40342 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S2390288AbgFYHlo (ORCPT ); Thu, 25 Jun 2020 03:41:44 -0400 X-Greylist: delayed 400 seconds by postgrey-1.37 at lindbergh.monkeyblade.net; Thu, 25 Jun 2020 00:41:44 PDT Received: from mout-p-103.mailbox.org (mout-p-103.mailbox.org [IPv6:2001:67c:2050::465:103]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 922B2C061573; Thu, 25 Jun 2020 00:41:44 -0700 (PDT) Received: from smtp1.mailbox.org (smtp1.mailbox.org [IPv6:2001:67c:2050:105:465:1:1:0]) (using TLSv1.2 with cipher ECDHE-RSA-CHACHA20-POLY1305 (256/256 bits)) (No client certificate requested) by mout-p-103.mailbox.org (Postfix) with ESMTPS id 49ssHB268wzKmgv; Thu, 25 Jun 2020 09:35:02 +0200 (CEST) X-Virus-Scanned: amavisd-new at heinlein-support.de DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gorani.run; s=MBO0001; t=1593070500; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=30dYw6jJSc3h50zr6f6o1QF9VOz2xKEDt+vOebdkixg=; b=n08L3MBTph5lqmuRJ2kmDCcR6yET3yCAq0yBhTwz5owm1W5+KKQdSKdxxEWmJI36EJxyw4 fOP03et5MpGm8V9mnexWInoZttjfy3C8isXOJZ52Tw/9vlq1CINL7jsEG/u6D5QCgn6X0I 7vNFVxvusEbX2gG+4uEG1jew7eeOT2vS15e5J1NmLZqf0Jlx8vW8d3vTgBbxxKVmlQ+D4G xKuJOeiTli4B+dhWTi6aMtsKAXXnDf9dRwD/s5VZFmCI+hALHQDXJfnc0krXbAav9lrNak VobZuvvvePGMueRiycbp2Oq0ZXrmS6FfSCBJuGu6Oy4WGTPYyCWT3xa4o5fDeQ== Received: from smtp1.mailbox.org ([80.241.60.240]) by spamfilter02.heinlein-hosting.de (spamfilter02.heinlein-hosting.de [80.241.56.116]) (amavisd-new, port 10030) with ESMTP id nWv_Bsve4R4C; Thu, 25 Jun 2020 09:34:58 +0200 (CEST) Subject: Re: [PATCH] gpio: add GPO driver for PCA9570 To: Andy Shevchenko Cc: Linus Walleij , Bartosz Golaszewski , Linux Kernel Mailing List , "open list:GPIO SUBSYSTEM" References: <20200623060526.29922-1-mans0n@gorani.run> From: Sungbo Eo Message-ID: <7965f173-2668-b122-1ba8-9fbf7d169e33@gorani.run> Date: Thu, 25 Jun 2020 16:34:52 +0900 MIME-Version: 1.0 In-Reply-To: Content-Type: text/plain; charset=utf-8; format=flowed Content-Language: en-US Content-Transfer-Encoding: 7bit X-MBO-SPAM-Probability: 0 X-Rspamd-Score: -2.19 / 15.00 / 15.00 X-Rspamd-Queue-Id: E2DD71811 X-Rspamd-UID: 6fbf59 Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 2020-06-24 22:01, Andy Shevchenko wrote: > On Tue, Jun 23, 2020 at 9:06 AM Sungbo Eo wrote: >> >> This patch adds support for the PCA9570 I2C GPO expander. > >> Tested in kernel 5.4 on an ipq40xx platform. >> >> This is my first time submitting a whole driver patch, and I'm not really familiar with this PCA expander series. >> Please let me know how I can improve this patch further. (Do I also need to document the DT compatible string?) >> >> FYI there's an unmerged patch for this chip. >> http://driverdev.linuxdriverproject.org/pipermail/driverdev-devel/2017-May/105602.html >> I don't have PCA9571 either so I didn't add support for it. > > My very first questions to such (simple) driver submissions is: Have > you conducted research of existing drivers and found that none is > suitable for this chip? > Do this and answer in a commit message, if it will be still valid. > I've done a more extensive research for i2c expanders and found out that gw-pld, max732x, pcf857x also use i2c_smbus_write_byte() without reg address. But their architectures are more complex than pca9570 and I'm not sure if I can make them compatible with pca9570. (I still don't understand what "quasi-bidirectional" in pcf857x means...)