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=-3.8 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS 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 BC26AC11F68 for ; Fri, 2 Jul 2021 16:50:23 +0000 (UTC) Received: from gabe.freedesktop.org (gabe.freedesktop.org [131.252.210.177]) (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 7D33661208 for ; Fri, 2 Jul 2021 16:50:23 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 7D33661208 Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=collabora.com Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=dri-devel-bounces@lists.freedesktop.org Received: from gabe.freedesktop.org (localhost [127.0.0.1]) by gabe.freedesktop.org (Postfix) with ESMTP id CA8A66E158; Fri, 2 Jul 2021 16:50:22 +0000 (UTC) Received: from bhuna.collabora.co.uk (bhuna.collabora.co.uk [46.235.227.227]) by gabe.freedesktop.org (Postfix) with ESMTPS id 0476F6E158 for ; Fri, 2 Jul 2021 16:50:21 +0000 (UTC) Received: from maud (unknown [IPv6:2600:8800:8c04:8c00::912b]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) (Authenticated sender: alyssa) by bhuna.collabora.co.uk (Postfix) with ESMTPSA id 59F6D1F44FD2; Fri, 2 Jul 2021 17:50:07 +0100 (BST) Date: Fri, 2 Jul 2021 12:49:55 -0400 From: Alyssa Rosenzweig To: Boris Brezillon Subject: Re: [PATCH v3 5/7] drm/panfrost: Add a new ioctl to submit batches Message-ID: References: <20210702143225.3347980-1-boris.brezillon@collabora.com> <20210702143225.3347980-6-boris.brezillon@collabora.com> <20210702173843.44b3e322@collabora.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20210702173843.44b3e322@collabora.com> X-BeenThere: dri-devel@lists.freedesktop.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: Direct Rendering Infrastructure - Development List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: Jason Ekstrand , Tomeu Vizoso , dri-devel@lists.freedesktop.org, Steven Price , Rob Herring , Alyssa Rosenzweig , Robin Murphy Errors-To: dri-devel-bounces@lists.freedesktop.org Sender: "dri-devel" > > What is handle? What is point? > > Handle is a syncobj handle, point is the point in a syncobj timeline. > I'll document those fields. OK. > > Why is there padding instead of putting point first? > > We can move the point field first, but we need to keep the explicit > padding: the struct has to be 64bit aligned because of the __u64 field > (which the compiler takes care of) but if we don't have an explicit > padding, the unused 32bits are undefined, which might cause trouble if > we extend the struct at some point, since we sort of expect that old > userspace keep this unused 32bit slot to 0, while new users set > non-zero values if they have to. Makes sense. Reordering still probably makes sense. > > ``` > > > #define PANFROST_BO_REF_EXCLUSIVE 0x1 > > > +#define PANFROST_BO_REF_NO_IMPLICIT_DEP 0x2 > > ``` > > > > This seems logically backwards. NO_IMPLICIT_DEP makes sense if we're > > trying to keep backwards compatibility, but here you're crafting a new > > interface totally from scratch. If anything, isn't BO_REF_IMPLICIT_DEP > > the flag you'd want? > > AFAICT, all other drivers make the no-implicit-dep an opt-in, and I > didn't want to do things differently in panfrost. But if that's really > an issue, I can make it an opt-out. I don't have strong feelings either way. I was just under the impressions other drivers did this for b/w compat reasons which don't apply here. > > Hmm. I'm not /opposed/ and I know kbase uses strides but it seems like > > somewhat unwarranted complexity, and there is a combinatoric explosion > > here (if jobs, bo refs, and syncobj refs use 3 different versions, as > > this encoding permits... as opposed to just specifying a UABI version or > > something like that) > > Sounds like a good idea. I'll add a version field and map that > to a tuple. Cc Steven, does this make sense? > > > + /** > > > + * If the submission fails, this encodes the index of the job > > > + * failed. > > > + */ > > > + __u32 fail_idx; > > ``` > > > > What if multiple jobs fail? > > We stop at the first failure. Note that it's not an execution failure, > but a submission failure (AKA, userspace passed wrong params, like > invalid BO or synobj handles). I see, ok.