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 X-Spam-Level: X-Spam-Status: No, score=-3.8 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS autolearn=no autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id D85A7C2D0CD for ; Tue, 17 Dec 2019 12:39:04 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id B85582146E for ; Tue, 17 Dec 2019 12:39:04 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727700AbfLQMjE convert rfc822-to-8bit (ORCPT ); Tue, 17 Dec 2019 07:39:04 -0500 Received: from mail-ot1-f68.google.com ([209.85.210.68]:33206 "EHLO mail-ot1-f68.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1727406AbfLQMjE (ORCPT ); Tue, 17 Dec 2019 07:39:04 -0500 Received: by mail-ot1-f68.google.com with SMTP id b18so5006836otp.0; Tue, 17 Dec 2019 04:39:03 -0800 (PST) X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:mime-version:references:in-reply-to:from:date :message-id:subject:to:cc:content-transfer-encoding; bh=LUh0j8xU1Qr9fXtE+2mw/twXvOy9bjYwMRuWrzxT6eQ=; b=EGqp9Wfg8QRJSwpL/3FHCCFImWhwvqbzihUigYc8FCp6e0Ul+zDPnsk/W/Km22NW3N ndKJcKQM/mqtjOjfU92mMem81l4XSdm5Iaugd3joN38a2uDsqPheTm3juR//j94klKmU R3iNS/6eMHwXWM/tsqsxtUoCgfcMy7Y+ApBFW2Md3luVH8JHywKKg6Stn43FLm7tmEJE KJNUjLnL0Zy2LUkJPYVrHqOzwmcVh0xRimHxtYjbWA8ddSsTTdL32A3jAlCamUu12DYK 3shmuhU4gTARrjbRzpJvr5yr9NOnu9/zaDso/54rtV2TWmKMP3Hgjx7Kwiq92gnsMaaC hSpQ== X-Gm-Message-State: APjAAAV8ABUSVTzamD6DIuMixL/VFXngkyC9EBHvcy6/X9uM6o84qryR 5yXKPaI/T6EN7VV6fkC630UCn0nwMK+yXWFSDA8= X-Google-Smtp-Source: APXvYqymQtdXQIA9dI50I0zDHkQvsxWBvf/GOqxNthXzUoE+3dKDkD4aXvjDConIraGDEKG0eShllvgWTqpNdNsUfFU= X-Received: by 2002:a9d:6c81:: with SMTP id c1mr38348507otr.39.1576586342848; Tue, 17 Dec 2019 04:39:02 -0800 (PST) MIME-Version: 1.0 References: <1573660292-10629-1-git-send-email-fabrizio.castro@bp.renesas.com> <1573660292-10629-7-git-send-email-fabrizio.castro@bp.renesas.com> <20191213171038.GH4860@pendragon.ideasonboard.com> In-Reply-To: From: Geert Uytterhoeven Date: Tue, 17 Dec 2019 13:38:51 +0100 Message-ID: Subject: Re: [PATCH v4 06/13] drm/bridge: lvds-codec: Add "lvds-decoder" support To: Fabrizio Castro Cc: Laurent Pinchart , Neil Armstrong , David Airlie , Daniel Vetter , Rob Herring , Mark Rutland , Andrzej Hajda , "devicetree@vger.kernel.org" , Chris Paterson , Geert Uytterhoeven , Kieran Bingham , Magnus Damm , "dri-devel@lists.freedesktop.org" , Biju Das , "linux-renesas-soc@vger.kernel.org" , Simon Horman , Jacopo Mondi , Peter Rosin Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: 8BIT Sender: devicetree-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: devicetree@vger.kernel.org Hi Fabrizio, On Tue, Dec 17, 2019 at 1:31 PM Fabrizio Castro wrote: > > From: linux-renesas-soc-owner@vger.kernel.org On Behalf Of Geert Uytterhoeven > > Sent: 17 December 2019 12:21 > > Subject: Re: [PATCH v4 06/13] drm/bridge: lvds-codec: Add "lvds-decoder" support > > > > On Tue, Dec 17, 2019 at 12:03 PM Fabrizio Castro > > wrote: > > > > From: Laurent Pinchart > > > > Sent: 13 December 2019 17:11 > > > > Subject: Re: [PATCH v4 06/13] drm/bridge: lvds-codec: Add "lvds-decoder" support > > > > > > > > On Wed, Nov 13, 2019 at 03:51:25PM +0000, Fabrizio Castro wrote: > > > > > Add support for transparent LVDS decoders by adding a new > > > > > compatible string ("lvds-decoder") to the driver. > > > > > This patch also adds member connector_type to struct lvds_codec, > > > > > and that's because LVDS decoders have a different connector type > > > > > from LVDS encoders. We fill this new member up with the data > > > > > matching the compatible string. > > > > > > > > > > Signed-off-by: Fabrizio Castro > > > > > --- a/drivers/gpu/drm/bridge/lvds-codec.c > > > > > +++ b/drivers/gpu/drm/bridge/lvds-codec.c > > > > > @@ -65,6 +67,7 @@ static int lvds_codec_probe(struct platform_device *pdev) > > > > > if (!lvds_codec) > > > > > return -ENOMEM; > > > > > > > > > > + lvds_codec->connector_type = (u32)of_device_get_match_data(&pdev->dev); > > > > > > > > I'm now getting a compilation failure here: > > > > > > > > drivers/gpu/drm/bridge/lvds-codec.c: In function ‘lvds_codec_probe’: > > > > drivers/gpu/drm/bridge/lvds-codec.c:68:31: error: cast from pointer to integer of different size [-Werror=pointer-to-int-cast] > > > > lvds_codec->connector_type = (u32)of_device_get_match_data(&pdev->dev); > > > > ^ > > > > > > > > The fix should be simple: > > > > > > > > lvds_codec->connector_type = (uintptr_t)of_device_get_match_data(dev); > > > > > > > > I'm bothered by the fact that I've compiled this before without any > > > > issue, so this really puzzles me. Do you get the same warning ? > > > > > > The warning appears when compiling for arm64, understandably so. > > > We must have compiled this for arm only the first time around. > > > > > > I think the right way to solve this is to either cast to (u32)(uintptr_t) or (u32)(unsigned long). > > > > Just casting to uintptr_t should be sufficient. > > It should be sufficient for the compiler, but I have seen examples where people > preferred to be explicit, like in: > drivers/mailbox/mtk-cmdq-mailbox.c > drivers/leds/leds-pm8058.c > > Since the kernel is increasing its tightness with respect to warnings, I personally prefer > (u32)(uintptr_t), even though not strictly necessary, but I am fine with (uintptr_t) if you > don't like (u32)(uintptr_t). It depends. I try to have as few casts as possible ("casts are evil"). While adding the extra (u32) cast makes it clearer that the intended result is a u32 (for now), it will cause silent truncation on 64-bit if connector_type is ever enlarged to unsigned long, and larger values are used. In this particular case this is unlikely, though, as unsigned long would still be 32-bit on 32-bit platforms, so the larger values cannot be used. Gr{oetje,eeting}s, Geert -- Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- geert@linux-m68k.org In personal conversations with technical people, I call myself a hacker. But when I'm talking to journalists I just say "programmer" or something like that. -- Linus Torvalds