From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 7C94BC54EAA for ; Mon, 23 Jan 2023 09:26:25 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S231799AbjAWJ0Y convert rfc822-to-8bit (ORCPT ); Mon, 23 Jan 2023 04:26:24 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:60700 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229514AbjAWJ0X (ORCPT ); Mon, 23 Jan 2023 04:26:23 -0500 Received: from eu-smtp-delivery-151.mimecast.com (eu-smtp-delivery-151.mimecast.com [185.58.85.151]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id A9D511554E for ; Mon, 23 Jan 2023 01:26:21 -0800 (PST) Received: from AcuMS.aculab.com (156.67.243.121 [156.67.243.121]) by relay.mimecast.com with ESMTP with STARTTLS (version=TLSv1.2, cipher=TLS_ECDHE_RSA_WITH_AES_256_CBC_SHA384) id uk-mta-170-pWK5ZHwsNsOHzMuVCmnqRQ-1; Mon, 23 Jan 2023 09:26:18 +0000 X-MC-Unique: pWK5ZHwsNsOHzMuVCmnqRQ-1 Received: from AcuMS.Aculab.com (10.202.163.4) by AcuMS.aculab.com (10.202.163.4) with Microsoft SMTP Server (TLS) id 15.0.1497.45; Mon, 23 Jan 2023 09:26:18 +0000 Received: from AcuMS.Aculab.com ([::1]) by AcuMS.aculab.com ([::1]) with mapi id 15.00.1497.045; Mon, 23 Jan 2023 09:26:18 +0000 From: David Laight To: 'Javier Martinez Canillas' , "linux-kernel@vger.kernel.org" CC: Thomas Zimmermann , Daniel Vetter , David Airlie , "dri-devel@lists.freedesktop.org" Subject: RE: [PATCH] drm/ssd130x: Silence a `dubious: x & !y` warning Thread-Topic: [PATCH] drm/ssd130x: Silence a `dubious: x & !y` warning Thread-Index: AQHZLcwEpBlghOuKm0WPZwn3mEYKGa6rvUhg Date: Mon, 23 Jan 2023 09:26:17 +0000 Message-ID: References: <20230121190930.2804224-1-javierm@redhat.com> In-Reply-To: <20230121190930.2804224-1-javierm@redhat.com> Accept-Language: en-GB, en-US X-MS-Has-Attach: X-MS-TNEF-Correlator: x-ms-exchange-transport-fromentityheader: Hosted x-originating-ip: [10.202.205.107] MIME-Version: 1.0 X-Mimecast-Spam-Score: 0 X-Mimecast-Originator: aculab.com Content-Language: en-US Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8BIT Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: Javier Martinez Canillas > Sent: 21 January 2023 19:10 > > The sparse tool complains with the following warning: > > $ make M=drivers/gpu/drm/solomon/ C=2 > CC [M] drivers/gpu/drm/solomon/ssd130x.o > CHECK drivers/gpu/drm/solomon/ssd130x.c > drivers/gpu/drm/solomon/ssd130x.c:363:21: warning: dubious: x & !y > > This seems to be a false positive in my opinion but still we can silence > the tool while making the code easier to read. Let's also add a comment, > to explain why the "com_seq" logical not is used rather than its value. > > Reported-by: Thomas Zimmermann > Signed-off-by: Javier Martinez Canillas > Reviewed-by: Thomas Zimmermann > --- > > drivers/gpu/drm/solomon/ssd130x.c | 11 +++++++++-- > 1 file changed, 9 insertions(+), 2 deletions(-) > > diff --git a/drivers/gpu/drm/solomon/ssd130x.c b/drivers/gpu/drm/solomon/ssd130x.c > index c3bf3a18302e..b16330a8b624 100644 > --- a/drivers/gpu/drm/solomon/ssd130x.c > +++ b/drivers/gpu/drm/solomon/ssd130x.c > @@ -81,7 +81,7 @@ > #define SSD130X_SET_PRECHARGE_PERIOD2_MASK GENMASK(7, 4) > #define SSD130X_SET_PRECHARGE_PERIOD2_SET(val) FIELD_PREP(SSD130X_SET_PRECHARGE_PERIOD2_MASK, (val)) > #define SSD130X_SET_COM_PINS_CONFIG1_MASK GENMASK(4, 4) > -#define SSD130X_SET_COM_PINS_CONFIG1_SET(val) FIELD_PREP(SSD130X_SET_COM_PINS_CONFIG1_MASK, !(val)) > +#define SSD130X_SET_COM_PINS_CONFIG1_SET(val) FIELD_PREP(SSD130X_SET_COM_PINS_CONFIG1_MASK, (val)) How about just changing !(val) to (val) ? 0 : 1 It should shut the compiler up and is probably more descriptive. David - Registered Address Lakeside, Bramley Road, Mount Farm, Milton Keynes, MK1 1PT, UK Registration No: 1397386 (Wales)