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 bombadil.infradead.org (bombadil.infradead.org [198.137.202.133]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.lore.kernel.org (Postfix) with ESMTPS id 948B5C52D6F for ; Tue, 27 Aug 2024 09:30:26 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=lists.infradead.org; s=bombadil.20210309; h=Sender:List-Subscribe:List-Help :List-Post:List-Archive:List-Unsubscribe:List-Id:Content-Transfer-Encoding: Content-Type:In-Reply-To:From:References:Cc:To:Subject:MIME-Version:Date: Message-ID:Reply-To:Content-ID:Content-Description:Resent-Date:Resent-From: Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID:List-Owner; bh=2uDYEvB9ZuHs6Fp+WM/YHa3lCZTRQ2wSw7rHEBGo5k4=; b=nxHR4WXvhUGxmM/sLRgeoo2HYq cIS/ZxD1aoleZCGKEx6ohyGMML18YQXhTDLy8QzjksFTtNbO+WHTSIRYSaEkjtBrCUkTeLF4GBqS1 7vBMoqc+PO9lFEVJ54dVt+G9rdqa05z/BYpnWoSXXLWhwaw5mSEJmbeRnVNU8Dont5WjnHxOptDBJ l0jLUOg5HNLJJusO+irMo7xJPPGKDwtigLuKrvDNJwlVO+eM8esEO7l5PpQA/2+ZA0y2ygnL93AIk demtjJmkGAmoliUqntT2TEHs+5BadjFkwnOY6Huk298u2t0KmbuWFQAtsyw7fsGv8SMN8OJ9W+Tv1 GRpFL5gw==; 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charset=UTF-8 Content-Transfer-Encoding: 7bit X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20240827_022922_893424_1764B09C X-CRM114-Status: GOOD ( 16.87 ) X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.34 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+linux-arm-kernel=archiver.kernel.org@lists.infradead.org On 27/08/2024 11:22, Jan Kiszka wrote: > On 27.08.24 08:37, Krzysztof Kozlowski wrote: >> On Mon, Aug 26, 2024 at 11:50:04PM +0200, Jan Kiszka wrote: >>> From: Jan Kiszka >>> >>> Describe also the VMAP registers which are needed in order to make use >>> of the PVU with this PCI host. Furthermore, permit to specify a >>> restricted DMA pool by phandle. >> >> That's an ABI break without explanation why it is necessary. >> > > It is needed in order to support the PVU, as written above. Above say only that you want a new feature and that's not really suitable explanation for ABI break, because answer to this is: add new feature without breaking existing users. But maybe there is a bug or something does not work or never work or there are no users, don't know. > > Previous versions of this binding likely didn't consider this use case > and therefore didn't describe all registers associated with the hardware. > > BTW, if you see a way to add the required registers without breaking > more than needed, I'm all ears. At least the kernel driver will continue > to work with older DTs when you disable PVU support or do not add a DMA > pool to the DT. If there is no ABI break, because driver still handles correctly old DTB, then mention it in the commit msg. Best regards, Krzysztof