From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-alma10-1.taild15c8.ts.net [100.103.45.18]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 582B22EEE9E; Mon, 28 Sep 2026 22:24:44 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=100.103.45.18 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1790634285; cv=none; b=Dr/iaOXaVKHPYkhJyqB772PlkUMrmsBGglk3Cdj6agZOdtPC94EH7O0mAZWaQhL2EulbtqwX7CEQSKTfhOSOyN3F0uDgojWNZVbpoe9YsImcT8V8rL0LrhwR5csQ8l3EvakEa2cemLDQH6Mg57aGjUHRuAg91wjtN44WT3v5SNc= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1790634285; c=relaxed/simple; bh=CQ1sHx0JdzzR5DVXNUibmZyTLdxwADEgfkQSPEiTcW0=; h=Date:From:To:Cc:Subject:Message-ID:MIME-Version:Content-Type: Content-Disposition:In-Reply-To; b=DSVr9U9LZCTqflYl0DOw/r3iMRHKE/jaCGmy32KNimtC7uB2XD01EU6cfy2+k24cWDyfo6pnSpLyzZ+I1T6V/+ii18kae1l5zN/xukhPfQ4rk6RDyx66X6zD0UdSRXXmpfZ+daUNBL6Eq80TyJtipYr5C/xlUXKj9RKKLNZm5kk= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=F/m4TO+b; arc=none smtp.client-ip=100.103.45.18 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="F/m4TO+b" Received: by smtp.kernel.org (Postfix) with ESMTPSA id A16091F000FF; Mon, 28 Sep 2026 22:24:43 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel.org; s=k20260515; t=1790634283; bh=QXHVC5yMZceL5J1JsKV4vQfSwG3c2NxZWnu6Pfi0xFw=; h=Date:From:To:Cc:Subject:In-Reply-To; b=F/m4TO+b8y+Bwyx9DgGsfW0txIaTWEuEM6ClnjSJfebYcblSdTTjbzP1Fcioz33Pd z3mvkX5AA3HiF+s2GgpeYaqXzJNxX2cIb9F2uS6yG//b3i7eeqkqU+fusQmhy7ni6i zmSxlnBxTofWY65Q/tGeTVyQhIL9s/EEtOJ/6+9vtVPgEcN4QjaxRS0OBAxwGBuDsM vl4NblMQBj/oOcOrChd2PZJMbltqau8oJvI50Kx+BEqLH8uOINJAuCsGRWERYM8WMW kHViKsa++YJSl9B8dh2Q39BC/C2THqEfjkKB/ofLWXMqMUqQtxKe9SP4IWb349mMBh QjlNROFCx2nEg== Date: Mon, 28 Sep 2026 17:24:42 -0500 From: Bjorn Helgaas To: Marek Vasut Cc: linux-pci@vger.kernel.org, Krzysztof =?utf-8?Q?Wilczy=C5=84ski?= , Bjorn Helgaas , Conor Dooley , Geert Uytterhoeven , Krzysztof Kozlowski , Lorenzo Pieralisi , Manivannan Sadhasivam , Rob Herring , Yoshihiro Shimoda , devicetree@vger.kernel.org, linux-kernel@vger.kernel.org, linux-renesas-soc@vger.kernel.org Subject: Re: [PATCH v5 6/6] PCI: dwc: rcar-gen4: Add support for R-Car X5H PCIe4 Message-ID: <20260928222442.GA2266778@bhelgaas> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <3bb47958-09e2-4726-85e3-8e5d3873840e@mailbox.org> On Mon, Sep 28, 2026 at 11:32:37PM +0200, Marek Vasut wrote: > On 9/28/26 11:01 PM, Bjorn Helgaas wrote: > > On Mon, Sep 21, 2026 at 10:27:48PM +0200, Marek Vasut wrote: > > > Add support for R8A78000 (R-Car X5H) PCIe4. > > > > > > This driver previously supported R-Car Gen4 S4/V4H/V4M. PCIe features > > > of R-Car X5H PCIe4 are almost all the same. > > > > > > The controller initialization sequence is slightly different and is > > > factored out into controller specific callbacks, in a manner similar > > > to previous R-Car Gen4 handling. > > > > > > The controller does have a PHY attached to it, but the PHY is operated > > > by a separate PHY driver, the PHY driver instance binding is handled > > > in rcar_gen4_pcie_get_resources() and controlled in the aforementioned > > > controller specific callbacks. > > > > > > The controller driver is deliberately using "renesas,rcar-gen5-pcie4" > > > DT compatible string to discern R-Car X5H PCIe4 controller supported > > > by this driver, from R-Car X5H PCIe6 controller which will most likely > > > use a separate driver. > > > > The gen5/pcie4 usage is confusing. > > > > I often push back on things like "PCIe Gen4" because it's ambiguous > > (does it mean "compliant with base spec r4.0" or "supports 16 GT/s" or > > something else), but it's so widely used to mean transfer rate that > > it's hard to resist, and the best I can hope for is clarification. > > > > But in "renesas,rcar-gen5-pcie4", I don't know what the 5 and the 4 > > mean. Maybe "gen5" refers to some internal R-Car thing, and "pcie4" > > is something like "PCIe Gen4, i.e., 16 GT/s"? > > Gen5 refers to R-Car Gen5 (5th R-Car SoC generation). > > PCIe4 refers to the PCIe Gen4 core in the R-Car Gen5 SoC. There is also PCIe > Gen6 core in the same SoC, but that will require a different driver and > different compatible string. > > Since none of this shipped in any kernel version yet, would you prefer some > sort of rename ? I can send patches. Huh. TIL that pcie-rcar-gen4.c refers to the 4th generation R-Car SoCs (and, I guess the point of this series is to add support for 5th generation SoCs), not to PCIe Gen4 link speeds. I see that "renesas,rcar-genX" is all over the place in 'compatible' strings, so I guess we should follow that precedent. If the "renesas,rcar-gen5" SoC includes both PCIe Gen4 and PCIe Gen6 cores, I suppose everybody refers to them as pcie-gen4 and pcie-gen6, so the "renesas,rcar-gen5-pcie4" you used is probably the obvious choice. But maybe we can make commit logs less confusing by saying things like: - R-Car Gen4 SoCs S4/V4H/V4M - R-Car Gen5 SoC X5H - the R-Car Gen5 SoC PCIe Gen4 core - the R-Car R8A78000 X5H PCIe Gen4 core, which supports a x8 link at 16 GT/s