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 X-Spam-Level: X-Spam-Status: No, score=-5.5 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI, NICE_REPLY_A,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED,USER_AGENT_SANE_1 autolearn=no autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 36C3EC4363A for ; Thu, 29 Oct 2020 14:15:23 +0000 (UTC) Received: from merlin.infradead.org (merlin.infradead.org [205.233.59.134]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPS id 9B44A2076B for ; Thu, 29 Oct 2020 14:15:22 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=lists.infradead.org header.i=@lists.infradead.org header.b="MQVSYruZ" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 9B44A2076B Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=arm.com Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=linux-rockchip-bounces+linux-rockchip=archiver.kernel.org@lists.infradead.org DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=lists.infradead.org; s=merlin.20170209; h=Sender:Content-Type: Content-Transfer-Encoding:Cc:List-Subscribe:List-Help:List-Post:List-Archive: List-Unsubscribe:List-Id:In-Reply-To:MIME-Version:Date:Message-ID:From: References:To:Subject:Reply-To:Content-ID:Content-Description:Resent-Date: Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID:List-Owner; bh=zUwPgy4h5pdYkyg85jVEJezgoR8V/XkY5dWucakW1+k=; b=MQVSYruZaR6O8EJA2qpByHTXy 9FeadaH0lWXja+0Kxe/ZYWLLf0qvTa2b/NLsvC2ze2nUSpXsa3hxPzSWc+HCQ//ylHYkRdaI5ImuA pB8/pviuner4jo/DHGB0pgFhHKaoNZL5LZktYrfgTW2oXDkGnF7K3UeX9fmmuYNzqMHwOnFU/sOj0 EmSCRQO+acc5VfGX0dahxgvTZRW3Boevn8O/Fy1rrZ/M/0jfWnGMHU1PugzngwQ6IZmXUXKw0Iuxl eDcqg3QUI7WoH8antpZAs47aGkhrw6PL09D30RVlZHeyoqWa/GtHigAAFgTLLKf4zt4U86gHdE9ND ysAzmWPxA==; Received: from localhost ([::1] helo=merlin.infradead.org) by merlin.infradead.org with esmtp (Exim 4.92.3 #3 (Red Hat Linux)) id 1kY8hw-0005S7-HO; Thu, 29 Oct 2020 14:15:16 +0000 Received: from foss.arm.com ([217.140.110.172]) by merlin.infradead.org with esmtp (Exim 4.92.3 #3 (Red Hat Linux)) id 1kY8hu-0005RT-D5 for linux-rockchip@lists.infradead.org; Thu, 29 Oct 2020 14:15:15 +0000 Received: from usa-sjc-imap-foss1.foss.arm.com (unknown [10.121.207.14]) by usa-sjc-mx-foss1.foss.arm.com (Postfix) with ESMTP id 62125139F; Thu, 29 Oct 2020 07:15:13 -0700 (PDT) Received: from [10.57.54.223] (unknown [10.57.54.223]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPSA id 7A0533F719; Thu, 29 Oct 2020 07:15:11 -0700 (PDT) Subject: Re: [PATCH 00/18] Add Hantro regmap and VC8000 h264 decode support To: Ezequiel Garcia , Adrian Ratiu , Philipp Zabel References: <20201012205957.889185-1-adrian.ratiu@collabora.com> From: Robin Murphy Message-ID: <0dd9fb9d-3f33-b9b0-a7a8-6d3111e92d64@arm.com> Date: Thu, 29 Oct 2020 14:15:10 +0000 User-Agent: Mozilla/5.0 (Windows NT 10.0; rv:78.0) Gecko/20100101 Thunderbird/78.4.0 MIME-Version: 1.0 In-Reply-To: Content-Language: en-GB X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20201029_101514_612653_0B21D56A X-CRM114-Status: GOOD ( 32.13 ) X-BeenThere: linux-rockchip@lists.infradead.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: Upstream kernel work for Rockchip platforms List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: Fruehberger Peter , kernel@collabora.com, linux-kernel@vger.kernel.org, linux-rockchip@lists.infradead.org, Mark Brown , kuhanh.murugasen.krishnan@intel.com, Daniel Vetter , Mauro Carvalho Chehab , linux-media@vger.kernel.org Content-Transfer-Encoding: 7bit Content-Type: text/plain; charset="us-ascii"; Format="flowed" Sender: "Linux-rockchip" Errors-To: linux-rockchip-bounces+linux-rockchip=archiver.kernel.org@lists.infradead.org On 2020-10-29 13:07, Ezequiel Garcia wrote: > Hello Adrian, > > On Mon, 2020-10-12 at 23:59 +0300, Adrian Ratiu wrote: >> Dear all, >> >> This series introduces a regmap infrastructure for the Hantro driver >> which is used to compensate for different HW-revision register layouts. >> To justify it h264 decoding capability is added for newer VC8000 chips. >> >> This is a gradual conversion to the new infra - a complete conversion >> would have been very big and I do not have all the HW yet to test (I'm >> expecting a RK3399 shipment next week though ;). I think converting the >> h264 decoder provides a nice blueprint for how the other codecs can be >> converted and enabled for different HW revisions. >> >> The end goal of this is to make the driver more generic and eliminate >> entirely custom boilerplate like `struct hantro_reg` or headers with >> core-specific bit manipulations like `hantro_g1_regs.h` and instead rely >> on the well-tested albeit more verbose regmap subsytem. >> >> To give just two examples of bugs which are easily discovered by using >> more verbose regmap fields (very easy to compare with the datasheets) >> instead of relying on bit-magic tricks: G1_REG_DEC_CTRL3_INIT_QP(x) was >> off-by-1 and the wrong .clk_gate bit was set in hantro_postproc.c. >> >> Anyway, this series also extends the MMIO regmap API to allow relaxed >> writes for the theoretical reason that avoiding unnecessary membarriers >> leads to less CPU usage and small improvements to battery life. However, >> in practice I could not measure differences between relaxed/non-relaxed >> IO, so I'm on the fence whether to keep or remove the relaxed calls. >> >> What I could masure is the performance impact of adding more sub-reg >> field acesses: a constant ~ 20 microsecond bump per G1 h264 frame. This >> is acceptable considering the total time to decode a frame takes three >> orders of magnitude longer, i.e. miliseconds ranges, depending on the >> frame size and bitstream params, so it is an acceptable trade-off to >> have a more generic driver. >> > > Before going forward with using regmap, I would like to have a sense > of the footprint it adds, and see if we can avoid that 20 us penalty. > > I'd also like to try another approach, something that has less > memory footprint and less runtime penalty. > > How about something like this: > > #define G1_PIC_WIDTH 4, 0xff8, 23 > #define ... > > struct hantro_swreg { > u32 value[399 /*whatever size goes here*/]; > }; > > void hantro_reg_write(struct hantro_swreg *r, > unsigned int swreg, u32 mask, u32 offset, u32 new_val) > { > r->value[swreg] = (r->value[swreg] & ~(mask)) | > ((new_val << offset) & mask); > } > > Which you can then use in a very similar way as the current proposal: > > hantro_reg_write(&swreg, G1_PIC_WIDTH, width); > > The first advantage here is that we no longer have any > footprint for the fields. > > The ugly macros for "4, 0xff8, 23" can be auto-generated from > existing vendor headers, when possible, so that shouldn't > bother us. > > The register set is "flushed" using _relaxed, but it > could be still costly. > > If that is indeed costly, perhaps we can avoid writing > the entire set by having a dirty bit somewhere. > > In any case, it's worth exploring our options first, I think. Or maybe the regmap API itself deserves extending with a "deferred" operating mode where updates to the cached state can be separated from committing that state to the underlying hardware. ...which, after a brief code search out of curiosity, apparently already exists in the form of regcache_cache_only()/regcache_sync(), so there's probably no need to reinvent it :) Robin. > > PS: Another option is to just fork RK3399 to its > own driver and call the day, given how different it is :) > > Thanks! > Ezequiel > > > > _______________________________________________ > Linux-rockchip mailing list > Linux-rockchip@lists.infradead.org > http://lists.infradead.org/mailman/listinfo/linux-rockchip > _______________________________________________ Linux-rockchip mailing list Linux-rockchip@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-rockchip