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 CCEAAC2BD09 for ; Fri, 12 Jul 2024 10:34:37 +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:In-Reply-To:Content-Type: MIME-Version:References:Message-ID:Subject:Cc:To:From:Date:Reply-To: Content-Transfer-Encoding:Content-ID:Content-Description:Resent-Date: Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID:List-Owner; bh=iDGa5szO/n1ciEOY7GV1euyfLLxSdlfsVkwRYrwR9yg=; b=SUMlO7f75S+4YiH9OIYyPFHZoF apBjzVd9ZKFE1wngePx8tAyoNWodmzbDuSOaH+KVWmtdHbM+5oc9dXCtxXirVbikK5phRqkCXoqqV 8zw+vBZBqORQQEzf3pKqFuus+f1q8zsGZ2qyWBz0IHvqBui3A8ItKdeewB8NcmT8QZ+LYv92sjW+r Oz5T/rXperrkU0P3HJJAsYOlarRNbtHs/Jz8G4LKb3LlSEQbhBHkbxhjLy84d1Lrt0OKxCvLBnrp2 LluPWYKRppP61Z2jZXpsxdZp1Sch8jfrC+jOL/ol/oghAaFQifrYZ5FO6zabtbp9/g7X9qMdthZXn tSOEU+xg==; Received: from localhost ([::1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.97.1 #2 (Red Hat Linux)) id 1sSDbf-0000000HKQr-2RvT; Fri, 12 Jul 2024 10:34:27 +0000 Received: from dfw.source.kernel.org ([2604:1380:4641:c500::1]) by bombadil.infradead.org with esmtps (Exim 4.97.1 #2 (Red Hat Linux)) id 1sSDbN-0000000HKLJ-2c5N for linux-arm-kernel@lists.infradead.org; Fri, 12 Jul 2024 10:34:10 +0000 Received: from smtp.kernel.org (transwarp.subspace.kernel.org [100.75.92.58]) by dfw.source.kernel.org (Postfix) with ESMTP id F01B561E62; Fri, 12 Jul 2024 10:34:08 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 14B89C32782; Fri, 12 Jul 2024 10:34:04 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1720780448; bh=tq4rb/Jo7ZVGqX1PpVuZm2HtEQ+odwrnEVHLJeesCkY=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=MQUQDzEqJFDg6VE7+0eam/OnRwDGVW8EAE41L2coocaKPQ5ATP0tbuL179yoxWYc4 X/XAY3K8xQdsPDGmuZbvNK2UPGs7y+/8I0wb9ASkfdLUfBJXMw4BBac8Xhu8qJjcMa +7En0bRkb9xnk302rcp5OWKUssdx1keqSAu8mwVJxEl2IkeNJwLuUgMcrmx9Gv5iRU KnWRvsXJgoIg6wNo2ZqUN3DqwoD8dXxe+eq1P14ropnaEl/2R5xfsdufwiatEa8GS6 +Wu7t4+JhfW7/Mk6P3YReJ0+ikRL687DST6tdNStph8mPjgwYzP0FABf7xLaeR8ED7 579x8rdhOCTWA== Date: Fri, 12 Jul 2024 12:34:01 +0200 From: Niklas Cassel To: Francesco Dolcini Cc: Rob Herring , Krzysztof Kozlowski , Nishanth Menon , Vignesh Raghavendra , Tero Kristo , Conor Dooley , Siddharth Vadapalli , Lorenzo Pieralisi , Krzysztof =?utf-8?Q?Wilczy=C5=84ski?= , Bjorn Helgaas , Francesco Dolcini , linux-arm-kernel@lists.infradead.org, devicetree@vger.kernel.org, linux-kernel@vger.kernel.org, linux-omap@vger.kernel.org, linux-pci@vger.kernel.org Subject: Re: [PATCH v1 0/2] PCI: ti: k3: Fix TI J721E PERST# polarity Message-ID: References: <20240703100036.17896-1-francesco@dolcini.it> <20240711152531.GA35875@francesco-nb> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20240711152531.GA35875@francesco-nb> X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20240712_033409_724489_03075596 X-CRM114-Status: GOOD ( 19.78 ) 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 Thu, Jul 11, 2024 at 05:25:31PM +0200, Francesco Dolcini wrote: > Hello Niklas, > > On Thu, Jul 11, 2024 at 04:21:34PM +0200, Niklas Cassel wrote: > > On Wed, Jul 03, 2024 at 12:00:34PM +0200, Francesco Dolcini wrote: > > > From: Francesco Dolcini > > > > > > Fix PCIe PERST# signal polarity in TI J721E used on TI K3 machines. > > > > > > PCIe PERST# needs to be de-asserted for PCIe to work, however, the driver is > > > doing the opposite and the device tree files are defining the signal with the > > > wrong polarity to cope with that. Fix both the driver and the affected DT > > > files. > > > > While I understand why you want to fix this, > > I'm not sure if you can actually do so without breaking device tree backwards > > compatibility. > > I understand this, and at the same time I know that this was done in the > past for exactly the same reason, see for example commit 87620512681a > ("PCI: apple: Fix PERST# polarity"). If you knew about it, I think that you should have stated that your are breaking DT compatibility in the commit message, while also explaining it is acceptable in your specific case. I didn't know that there were other examples of drivers doing this. Looking at your example, it seems that both: 1e33888fbe44 ("PCI: apple: Add initial hardware bring-up") and 87620512681a ("PCI: apple: Fix PERST# polarity") were first included in v5.16, so there was never a kernel release with only one of the commits. Anyway, I will eagerly await the DT maintainers feedback on this series. Kind regards, Niklas