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 8CD15CCA47C for ; Wed, 13 Jul 2022 20:42:25 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S237129AbiGMUmX (ORCPT ); Wed, 13 Jul 2022 16:42:23 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:35984 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S230026AbiGMUmU (ORCPT ); Wed, 13 Jul 2022 16:42:20 -0400 Received: from mail-qk1-x72c.google.com (mail-qk1-x72c.google.com [IPv6:2607:f8b0:4864:20::72c]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id AE29D3121C; Wed, 13 Jul 2022 13:42:19 -0700 (PDT) Received: by mail-qk1-x72c.google.com with SMTP id f14so9576126qkm.0; Wed, 13 Jul 2022 13:42:19 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20210112; h=date:from:to:cc:subject:message-id:references:mime-version :content-disposition:in-reply-to; bh=EgA3xZH3t9Zi9zRLOrZeaQRW5jyanhvvZI8yTDXgSs4=; b=e3pT9sVk4ebu5rxOkVvi3A5vzXF3/bx9rOT9OycSA2cJYBt0jTTnMtcmx66L1h8f3K HgERgnUfpUdtrTCrL5qNcQm2LccwN85lIvfgA0H8jmjV9qPJlelJn995PeGUUNhZLHbV yAZ5NMYOrjY73ZZwlPTBbuw/49518KwjQx1mwAVnBgVR5uZi6w8RRD3RKnXlSjSJoxbZ PdYzpYTrxHm3q7zwOiSFisCq4AIuWwktIaZFDkXHaZO/YvcLaBjFiqtcEBxanSMt4h9s UK9CvmS6OOZNcnJPNFpXhtKERK1US62God8WWgp294lvESo3sP+0hEpqkdnLot/0KZtp g8jQ== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; h=x-gm-message-state:date:from:to:cc:subject:message-id:references :mime-version:content-disposition:in-reply-to; bh=EgA3xZH3t9Zi9zRLOrZeaQRW5jyanhvvZI8yTDXgSs4=; b=GgAVxYJKH7pnTeu1Ugd4jtCVORCGzxhBN1ME9l45VyzvTMdGRGZRbq/pRe5Cs9U1ds 7+Kdfqx00QVvl7eQFs3PXiOTlg68oiBekpc2ThAwqHpw6zEiEEW7/z1gL+5i4Ra/aGwl zy+VepSvAM75iA8p7H9afZMxqF+id2socF9mQzFSHhUAFd6lWT7T/iSWTkYOJnjGFaXK jVLYhd1GBTb4PqWyLCCtfNfCZe8szfqW/fkkwg7+2S13gF/ubO3zAFC9rFk8ImT4tx8W wPFFF8xOOWbCqDdWv5waxrvCUkrclCfcQhmkOSe/HoD++w+WhQ7quWSvbukiNHNCUleh 6tvw== X-Gm-Message-State: AJIora9lBstuyyvkuXEbOjZkNL8Xq0MGCwe2aTglgHnQqAN8488O3nJk 37VtzqmPVQPEsHb3aXMpeRw= X-Google-Smtp-Source: AGRyM1v52gaCFcbVPmIqwbN58q5YtVm3AqVJBDc6aU4aFpenuHjRPorXmWi30FmHMGI23odMN4w6eQ== X-Received: by 2002:a37:806:0:b0:6b5:c19d:bbfc with SMTP id 6-20020a370806000000b006b5c19dbbfcmr90053qki.155.1657744938660; Wed, 13 Jul 2022 13:42:18 -0700 (PDT) Received: from localhost ([2601:4c1:c100:1230:7360:5d5d:6684:e04b]) by smtp.gmail.com with ESMTPSA id m6-20020ac807c6000000b00315a5fa4bf6sm10194336qth.7.2022.07.13.13.42.18 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Wed, 13 Jul 2022 13:42:18 -0700 (PDT) Date: Wed, 13 Jul 2022 13:42:17 -0700 From: Yury Norov To: Andy Shevchenko Cc: Sebastian Fricke , Linux Media Mailing List , Jernej Skrabec , knaerzche@gmail.com, Collabora Kernel ML , bob.beckett@collabora.com, Ezequiel Garcia , Mauro Carvalho Chehab , Greg Kroah-Hartman , Linux Kernel Mailing List , "open list:ARM/Rockchip SoC..." , linux-staging@lists.linux.dev, nicolas.dufresne@collabora.com, Andy Shevchenko , Rasmus Villemoes Subject: Re: [PATCH 3/6] bitops: bitmap helper to set variable length values Message-ID: References: <20220713163201.136202-1-sebastian.fricke@collabora.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Wed, Jul 13, 2022 at 10:14:24PM +0200, Andy Shevchenko wrote: > On Wed, Jul 13, 2022 at 9:44 PM Yury Norov wrote: > > On Wed, Jul 13, 2022 at 09:10:33PM +0200, Andy Shevchenko wrote: > > > On Wed, Jul 13, 2022 at 8:56 PM Yury Norov wrote: > > > > On Wed, Jul 13, 2022 at 06:31:59PM +0200, Sebastian Fricke wrote: > > > > > > ... > > > > > > > I'd suggest you to try implementing > > > > bitmap_copy_from(dst, src, dst_off, len) > > > > or even > > > > bitmap_copy_from(dst, dst_off, src, src_off, len) > > > > if you expect that you'll need more flexibility in the future. > > > > > > Do you think it would be useful? > > > > > > We have bitmap_replace() & bitmap_remap(). Wouldn't that be enough? > > > > bitmap_replace and bitmap_remap have no an 'offset' parameter. > > True. > > But then it's a bit too generic to have this src_off, no? That's why I said: > > > > if you expect that you'll need more flexibility in the future. My preferred option is bitmap_copy_from(dst, src, dst_off, len). > I would rather expect for asymmetrical bitmaps that the other side > will be either one of the fixed width types (it makes sense to have > for 32- or 64-bit arguments. Look at patch #6 - it copies 1,4,5,9,10,32,37... - pretty much a random number number of bits. > When you have a source bitmap of x bits and you would like to copy it > into a y-bit one, I would think that either you have a small amount of > bits in x anyway, or x is a full-sized bitmap (same order as y). It sounds like a speculation to me. Why shouldn't we let people to copy with an offset any number of bits? > Also > keep in mind that granularity is long, so less than long it makes no > sense. > > bitmap_copy_from_T(unsigned long *map, start, len, T src), > > where T is type, start is the offset in map, len is the amount of bits > from src starting from 0. That's what is required in most of the cases > I believe. But not in Sebastian's case, according to patch #6. Thanks, Yury