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 24FD6C77B7A for ; Sat, 10 Jun 2023 18:15:05 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S230450AbjFJSPE (ORCPT ); Sat, 10 Jun 2023 14:15:04 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:48370 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229464AbjFJSPC (ORCPT ); Sat, 10 Jun 2023 14:15:02 -0400 Received: from dfw.source.kernel.org (dfw.source.kernel.org [139.178.84.217]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id A3C241FFE; Sat, 10 Jun 2023 11:15:01 -0700 (PDT) Received: from smtp.kernel.org (relay.kernel.org [52.25.139.140]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by dfw.source.kernel.org (Postfix) with ESMTPS id 30F6960DE1; Sat, 10 Jun 2023 18:15:01 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 640AFC433EF; Sat, 10 Jun 2023 18:14:58 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1686420900; bh=GKPQxfUo7uZW5Gd24x7KvPKVI05y3+NdpM2kKSoZnSE=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=XJE5DuwsZcTBlN19+6/DEwAd9aFw3/uwDKB1+Me4H8zquGcujmwnBVUXlna8UmG7o VdZugEjKVvh0AItKK8yDmgOlw56DHbMvCzerk6+vaqot5CjqwWFvr2geuOxlyqAR6I 6r1MNabOvEgXbNMax2dHuiuBbKkarVelFLl3P+McWD1uygZKak+dTiCYF/2lbidhwp DAXbztcXHmm2A46MHSdYtKyRuZJyV0OpKXM/5U4G/hCYi0eUCmZ5kF9A+4rS1THnY1 lHCvDHTqy2+eKgCXBpZW3hWdLIRFvR+mrjFTQPp2wD9F1nxKnjQYCdHm3hXl1dVc3R Q/QwKR9c2/UXg== Date: Sat, 10 Jun 2023 19:14:55 +0100 From: Conor Dooley To: Javier Martinez Canillas Cc: devicetree@vger.kernel.org, Conor Dooley , Thomas Zimmermann , Krzysztof Kozlowski , linux-kernel@vger.kernel.org, Maxime Ripard , Rob Herring , Geert Uytterhoeven , dri-devel@lists.freedesktop.org Subject: Re: [PATCH v2 2/5] dt-bindings: display: ssd1307fb: Remove default width and height values Message-ID: <20230610-unused-engaged-c1f4119cff08@spud> References: <20230609170941.1150941-1-javierm@redhat.com> <20230609170941.1150941-3-javierm@redhat.com> <20230610-opposite-quality-81d4a1561c88@spud> <87r0qj19zs.fsf@minerva.mail-host-address-is-not-set> MIME-Version: 1.0 Content-Type: multipart/signed; micalg=pgp-sha256; protocol="application/pgp-signature"; boundary="HYo4J/ldqvkCxGP1" Content-Disposition: inline In-Reply-To: <87r0qj19zs.fsf@minerva.mail-host-address-is-not-set> Precedence: bulk List-ID: X-Mailing-List: devicetree@vger.kernel.org --HYo4J/ldqvkCxGP1 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline Content-Transfer-Encoding: quoted-printable On Sat, Jun 10, 2023 at 07:51:35PM +0200, Javier Martinez Canillas wrote: > Conor Dooley writes: >=20 > > On Fri, Jun 09, 2023 at 07:09:37PM +0200, Javier Martinez Canillas wrot= e: > >> A default resolution in the ssd130x driver isn't set to an arbitrary 9= 6x16 > >> anymore. Instead is set to a width and height that's controller depend= ent. > > > > Did that change to the driver not break backwards compatibility with > > existing devicetrees that relied on the default values to get 96x16? > > >=20 > It would but I don't think it is an issue in pratice. Most users of these > panels use one of the multiple libraries on top of the spidev interface. >=20 > For the small userbase that don't, I believe that they will use the rpif > kernel and ssd1306-overlay.dtbo DTB overlay, which defaults to width=3D128 > and height=3D64 [1]. So those users will have to explicitly set a width a= nd > height for a 96x16 panel anyways. >=20 > The intersection of users that have a 96x16 panel, assumed that default > and consider the DTB a stable ABI, and only update their kernel but not > the DTB should be very small IMO. It's the adding of new defaults that makes it a bit messier, since you can't even revert without potentially breaking a newer user. I'd be more inclined to require the properties, rather change their defaults in the binding, lest there are people relying on them. If you and the other knowledgeable folk in the area really do know such users do not exist then I suppose it is fine to do. --HYo4J/ldqvkCxGP1 Content-Type: application/pgp-signature; name="signature.asc" -----BEGIN PGP SIGNATURE----- iHUEABYIAB0WIQRh246EGq/8RLhDjO14tDGHoIJi0gUCZIS9nwAKCRB4tDGHoIJi 0pU2AQDHz7mE6EbWFDwiRPNS1B2cx98/2aHLPV+NCbNKIozcTQD/Z67czcjETZHa LtdkpASNCb1wsRO4PqBs3OegWGbZIAM= =daWN -----END PGP SIGNATURE----- --HYo4J/ldqvkCxGP1--