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 vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id A2C16EB64D7 for ; Fri, 30 Jun 2023 13:20:21 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S232525AbjF3NUU (ORCPT ); Fri, 30 Jun 2023 09:20:20 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:45962 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S232480AbjF3NUT (ORCPT ); Fri, 30 Jun 2023 09:20:19 -0400 Received: from esa.microchip.iphmx.com (esa.microchip.iphmx.com [68.232.153.233]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 20BEA3A81; Fri, 30 Jun 2023 06:20:18 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=microchip.com; i=@microchip.com; q=dns/txt; s=mchp; t=1688131218; x=1719667218; h=date:from:to:cc:subject:message-id:references: mime-version:in-reply-to; bh=EaJ77L8/k3Hf0KmA9VK9enDoW0KMpkjzS7BilECDl2A=; b=zNSTiHPPjPJnIj1KJ98izycMouV3yTak2XgvVfFNuQVlPdS3pyVLRVD3 VQw5eUu+Al+WkJdlc2ICzdhXPP8ADplTCogp33X9TGZwb9WEjKC3XBMbf OJlQgBHmoWX1H0eDEgkPJSAbUutgSTmOoTK4YEZnom2qDmMQxUHlBy1xL YEI4TWGwz7hpHg3XWtwgvjUDB050Q/5R4smaipRfk4jCgz2PHGRkIYZhd wAsDQrMut1PiCXw5d48s6ghJOuCv9uv1md2EKYwrlL50tFoy9O7y7T90t yN1HiVmViVMBj5BTj7BdO2IxPQdjOumvDDtiQM5OmhDMo5WZzBAHV+pS4 w==; X-IronPort-AV: E=Sophos;i="6.01,170,1684825200"; d="asc'?scan'208";a="221422464" X-Amp-Result: UNKNOWN X-Amp-Original-Verdict: FILE UNKNOWN Received: from unknown (HELO email.microchip.com) ([170.129.1.10]) by esa5.microchip.iphmx.com with ESMTP/TLS/AES256-SHA256; 30 Jun 2023 06:20:18 -0700 Received: from chn-vm-ex01.mchp-main.com (10.10.85.143) by chn-vm-ex03.mchp-main.com (10.10.85.151) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256) id 15.1.2507.21; Fri, 30 Jun 2023 06:20:17 -0700 Received: from wendy (10.10.115.15) by chn-vm-ex01.mchp-main.com (10.10.85.143) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256) id 15.1.2507.21 via Frontend Transport; Fri, 30 Jun 2023 06:20:15 -0700 Date: Fri, 30 Jun 2023 14:19:46 +0100 From: Conor Dooley To: Andrew Jones CC: Conor Dooley , Palmer Dabbelt , , , Paul Walmsley , , , Evan Green , , , , Subject: Re: [PATCH v2 10/10] RISC-V: provide a Kconfig option to disable parsing "riscv,isa" Message-ID: <20230630-urgency-emission-882cd52a7a27@wendy> References: <20230629-landed-popsicle-ab46ab3b46d9@spud> <20230629-angled-gallantly-8fe7451a25fa@spud> <20230630-7d0f6fe66c9415315d491f15@orel> MIME-Version: 1.0 Content-Type: multipart/signed; micalg=pgp-sha256; protocol="application/pgp-signature"; boundary="o4a1LRPZt0ieGy5D" Content-Disposition: inline In-Reply-To: <20230630-7d0f6fe66c9415315d491f15@orel> Precedence: bulk List-ID: X-Mailing-List: devicetree@vger.kernel.org --o4a1LRPZt0ieGy5D Content-Type: text/plain; charset=us-ascii Content-Disposition: inline Content-Transfer-Encoding: quoted-printable On Fri, Jun 30, 2023 at 09:46:48AM +0200, Andrew Jones wrote: > On Thu, Jun 29, 2023 at 10:44:18PM +0100, Conor Dooley wrote: > > On Thu, Jun 29, 2023 at 02:16:49PM -0700, Palmer Dabbelt wrote: > > > On Thu, 29 Jun 2023 13:20:55 PDT (-0700), Conor Dooley wrote: > ... > > > > +bool __initdata riscv_isa_fallback_cmdline =3D false; > > > > +static int __init riscv_isa_fallback_setup(char *__unused) > > >=20 > > > Maybe it's better to support =3Dtrue and =3Dfalse here? Not sure it = matters, > > > we're already down a rabbit hole ;) > >=20 > > Dunno, not implemented a cmdline param before. Seemed "cleaner" to check > > for presence, don't really care so I'll adapt to w/e. > > >=20 > I don't have a strong preference here, but to throw in more food for > thought, I see this DT-v1 vs. DT-v2 choice to be a bit analogous to the > DT vs. ACPI choice. The 'acpi' command line parameter, for RISC-V, can > be 'off', 'on', and 'force', where >=20 > off -- disable ACPI if default was on > on -- enable ACPI but allow fallback to DT > force -- enable ACPI if default was off >=20 > So, if the default of the isa fallback command line option will depend on > Kconfig, then we may also want a 'force'. I'm not sure that I understand what "force" would give us. There's 4 cases: - CONFIG_RISCV_ISA_FALLBACK is enabled, cmdline option is present: cmdline option is ignored, fallback is taken if needed. crash if neither are present. - CONFIG_RISCV_ISA_FALLBACK is enabled, cmdline option is not present: cmdline option is ignored, fallback is taken if needed. crash if neither are present. - CONFIG_RISCV_ISA_FALLBACK is disabled, cmdline option is present: cmdline option takes priority, fallback is taken if needed. crash if neither are present. - CONFIG_RISCV_ISA_FALLBACK is disabled, cmdline option is not present: fallback is never taken crash if new properties aren't present. I don't really see the value in having an equivalent to acpi=3Doff, because the order of precedence is, to use your naming, "DT-v2" falling back to "DT-v1" & the default value concerns the use of the fallback. For ACPI, it is the other way around & the option controls the use of "DT-v2"'s analogue. Trying to slot in that logic: - CONFIG_RISCV_ISA_FALLBACK is enabled, cmdline option "=3Don": cmdline option is ignored, fallback is taken if needed. crash if neither are present. - CONFIG_RISCV_ISA_FALLBACK is enabled, cmdline option "=3Doff": cmdline option is prioritised, fallback is taken if needed. crash if new properties aren't present. - CONFIG_RISCV_ISA_FALLBACK is disabled, cmdline option "=3Don": cmdline option is prioritised, fallback is taken if needed. crash if neither are present. - CONFIG_RISCV_ISA_FALLBACK is disabled, cmdline option "=3Doff": fallback is never taken crash if new properties aren't present. I think I prefer the behaviour of what I currently have & I don't really get where the "force" option is supposed to fit in either? Cheers, Conor. --o4a1LRPZt0ieGy5D Content-Type: application/pgp-signature; name="signature.asc" -----BEGIN PGP SIGNATURE----- iHUEABYIAB0WIQRh246EGq/8RLhDjO14tDGHoIJi0gUCZJ7WZwAKCRB4tDGHoIJi 0gMcAQChwEuzvhSORcS7/4Mm0GXlyvRmOlOfWOHtGmwWRFmLMgD+JzMMaxJwKmej f/W/6SoUrX44MMben0skWQdfEYtTNQo= =N0ZM -----END PGP SIGNATURE----- --o4a1LRPZt0ieGy5D--