From: Geert Uytterhoeven <geert@linux-m68k.org> To: Fabrizio Castro <fabrizio.castro@bp.renesas.com> Cc: Laurent Pinchart <laurent.pinchart@ideasonboard.com>, Neil Armstrong <narmstrong@baylibre.com>, David Airlie <airlied@linux.ie>, Daniel Vetter <daniel@ffwll.ch>, Rob Herring <robh+dt@kernel.org>, Mark Rutland <mark.rutland@arm.com>, Andrzej Hajda <a.hajda@samsung.com>, "devicetree@vger.kernel.org" <devicetree@vger.kernel.org>, Chris Paterson <Chris.Paterson2@renesas.com>, Geert Uytterhoeven <geert+renesas@glider.be>, Kieran Bingham <kieran.bingham+renesas@ideasonboard.com>, Magnus Damm <magnus.damm@gmail.com>, "dri-devel@lists.freedesktop.org" <dri-devel@lists.freedesktop.org>, Biju Das <biju.das@bp.renesas.com>, "linux-renesas-soc@vger.kernel.org" <linux-renesas-soc@vger.kernel.org>, Simon Horman <horms@verge.net.au>, Jacopo Mondi <jacopo+renesas@jmondi.org>, Peter Rosin <peda@axentia.se> Subject: Re: [PATCH v4 06/13] drm/bridge: lvds-codec: Add "lvds-decoder" support Date: Tue, 17 Dec 2019 13:38:51 +0100 [thread overview] Message-ID: <CAMuHMdVqHekyeOaHwpFyG5buNZp-XmvGizqZ=Gbg40_=NL+s2A@mail.gmail.com> (raw) In-Reply-To: <TY1PR01MB17705FC08F72875484DF2208C0500@TY1PR01MB1770.jpnprd01.prod.outlook.com> Hi Fabrizio, On Tue, Dec 17, 2019 at 1:31 PM Fabrizio Castro <fabrizio.castro@bp.renesas.com> wrote: > > From: linux-renesas-soc-owner@vger.kernel.org <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 > > <fabrizio.castro@bp.renesas.com> wrote: > > > > From: Laurent Pinchart <laurent.pinchart@ideasonboard.com> > > > > 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 <fabrizio.castro@bp.renesas.com> > > > > > --- 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
WARNING: multiple messages have this Message-ID (diff)
From: Geert Uytterhoeven <geert@linux-m68k.org> To: Fabrizio Castro <fabrizio.castro@bp.renesas.com> Cc: Mark Rutland <mark.rutland@arm.com>, "devicetree@vger.kernel.org" <devicetree@vger.kernel.org>, Chris Paterson <Chris.Paterson2@renesas.com>, Geert Uytterhoeven <geert+renesas@glider.be>, Neil Armstrong <narmstrong@baylibre.com>, David Airlie <airlied@linux.ie>, Simon Horman <horms@verge.net.au>, Kieran Bingham <kieran.bingham+renesas@ideasonboard.com>, Magnus Damm <magnus.damm@gmail.com>, "dri-devel@lists.freedesktop.org" <dri-devel@lists.freedesktop.org>, Biju Das <biju.das@bp.renesas.com>, "linux-renesas-soc@vger.kernel.org" <linux-renesas-soc@vger.kernel.org>, Rob Herring <robh+dt@kernel.org>, Jacopo Mondi <jacopo+renesas@jmondi.org>, Laurent Pinchart <laurent.pinchart@ideasonboard.com>, Peter Rosin <peda@axentia.se> Subject: Re: [PATCH v4 06/13] drm/bridge: lvds-codec: Add "lvds-decoder" support Date: Tue, 17 Dec 2019 13:38:51 +0100 [thread overview] Message-ID: <CAMuHMdVqHekyeOaHwpFyG5buNZp-XmvGizqZ=Gbg40_=NL+s2A@mail.gmail.com> (raw) In-Reply-To: <TY1PR01MB17705FC08F72875484DF2208C0500@TY1PR01MB1770.jpnprd01.prod.outlook.com> Hi Fabrizio, On Tue, Dec 17, 2019 at 1:31 PM Fabrizio Castro <fabrizio.castro@bp.renesas.com> wrote: > > From: linux-renesas-soc-owner@vger.kernel.org <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 > > <fabrizio.castro@bp.renesas.com> wrote: > > > > From: Laurent Pinchart <laurent.pinchart@ideasonboard.com> > > > > 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 <fabrizio.castro@bp.renesas.com> > > > > > --- 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 _______________________________________________ dri-devel mailing list dri-devel@lists.freedesktop.org https://lists.freedesktop.org/mailman/listinfo/dri-devel
next prev parent reply other threads:[~2019-12-17 12:39 UTC|newest] Thread overview: 118+ messages / expand[flat|nested] mbox.gz Atom feed top 2019-11-13 15:51 [PATCH v4 00/13] Add LCD panel support to iwg20d Fabrizio Castro 2019-11-13 15:51 ` Fabrizio Castro 2019-11-13 15:51 ` [PATCH v4 01/13] dt-bindings: display: bridge: Convert lvds-transmitter binding to json-schema Fabrizio Castro 2019-11-13 15:51 ` Fabrizio Castro 2019-11-18 21:35 ` Rob Herring 2019-11-18 21:35 ` Rob Herring 2019-11-18 21:35 ` Rob Herring 2019-11-18 23:51 ` Laurent Pinchart 2019-11-18 23:51 ` Laurent Pinchart 2019-11-13 15:51 ` [PATCH v4 02/13] dt-bindings: display: bridge: lvds-transmitter: Document powerdown-gpios Fabrizio Castro 2019-11-13 15:51 ` Fabrizio Castro 2019-11-18 21:36 ` Rob Herring 2019-11-18 21:36 ` Rob Herring 2019-11-18 21:36 ` Rob Herring 2019-11-18 23:55 ` Laurent Pinchart 2019-11-18 23:55 ` Laurent Pinchart 2019-11-13 15:51 ` [PATCH v4 03/13] dt-bindings: display: bridge: lvds-transmitter: Absorb ti,ds90c185.txt Fabrizio Castro 2019-11-13 15:51 ` [PATCH v4 03/13] dt-bindings: display: bridge: lvds-transmitter: Absorb ti, ds90c185.txt Fabrizio Castro 2019-11-18 21:38 ` [PATCH v4 03/13] dt-bindings: display: bridge: lvds-transmitter: Absorb ti,ds90c185.txt Rob Herring 2019-11-18 21:38 ` Rob Herring 2019-11-18 21:38 ` Rob Herring 2019-11-18 23:56 ` Laurent Pinchart 2019-11-18 23:56 ` Laurent Pinchart 2019-11-13 15:51 ` [PATCH v4 04/13] dt-bindings: display: bridge: lvds-transmitter: Document "ti,sn75lvds83" Fabrizio Castro 2019-11-13 15:51 ` [PATCH v4 04/13] dt-bindings: display: bridge: lvds-transmitter: Document "ti, sn75lvds83" Fabrizio Castro 2019-11-18 21:38 ` [PATCH v4 04/13] dt-bindings: display: bridge: lvds-transmitter: Document "ti,sn75lvds83" Rob Herring 2019-11-18 21:38 ` Rob Herring 2019-11-18 21:38 ` Rob Herring 2019-11-18 23:57 ` Laurent Pinchart 2019-11-18 23:57 ` Laurent Pinchart 2019-11-13 15:51 ` [PATCH v4 05/13] drm/bridge: Repurpose lvds-encoder.c Fabrizio Castro 2019-11-13 15:51 ` Fabrizio Castro 2019-11-19 0:00 ` Laurent Pinchart 2019-11-19 0:00 ` Laurent Pinchart 2019-11-13 15:51 ` [PATCH v4 06/13] drm/bridge: lvds-codec: Add "lvds-decoder" support Fabrizio Castro 2019-11-13 15:51 ` Fabrizio Castro 2019-11-19 0:02 ` Laurent Pinchart 2019-11-19 0:02 ` Laurent Pinchart 2019-12-13 17:10 ` Laurent Pinchart 2019-12-13 17:10 ` Laurent Pinchart 2019-12-16 21:22 ` Laurent Pinchart 2019-12-16 21:22 ` Laurent Pinchart 2019-12-17 11:02 ` Fabrizio Castro 2019-12-17 11:02 ` Fabrizio Castro 2019-12-17 12:21 ` Geert Uytterhoeven 2019-12-17 12:21 ` Geert Uytterhoeven 2019-12-17 12:31 ` Fabrizio Castro 2019-12-17 12:31 ` Fabrizio Castro 2019-12-17 12:38 ` Geert Uytterhoeven [this message] 2019-12-17 12:38 ` Geert Uytterhoeven 2019-12-17 13:54 ` Laurent Pinchart 2019-12-17 13:54 ` Laurent Pinchart 2019-12-17 22:06 ` Fabrizio Castro 2019-12-17 22:06 ` Fabrizio Castro 2019-12-17 23:08 ` Laurent Pinchart 2019-12-17 23:08 ` Laurent Pinchart 2019-12-18 12:00 ` Fabrizio Castro 2019-12-18 12:00 ` Fabrizio Castro 2019-12-17 23:07 ` [PATCH v4.1 " Laurent Pinchart 2019-12-17 23:07 ` Laurent Pinchart 2019-11-13 15:51 ` [PATCH v4 07/13] drm/bridge: lvds-codec: Simplify panel DT node localisation Fabrizio Castro 2019-11-13 15:51 ` Fabrizio Castro 2019-11-19 0:03 ` Laurent Pinchart 2019-11-19 0:03 ` Laurent Pinchart 2019-11-13 15:51 ` [PATCH v4 08/13] dt-bindings: display: bridge: Repurpose lvds-encoder Fabrizio Castro 2019-11-13 15:51 ` Fabrizio Castro 2019-11-18 21:40 ` Rob Herring 2019-11-18 21:40 ` Rob Herring 2019-11-18 21:40 ` Rob Herring 2019-11-19 0:07 ` Laurent Pinchart 2019-11-19 0:07 ` Laurent Pinchart 2019-11-19 10:35 ` Fabrizio Castro 2019-11-19 10:35 ` Fabrizio Castro 2019-11-13 15:51 ` [PATCH v4 09/13] dt-bindings: display: bridge: lvds-codec: Document ti,ds90cf384a Fabrizio Castro 2019-11-13 15:51 ` [PATCH v4 09/13] dt-bindings: display: bridge: lvds-codec: Document ti, ds90cf384a Fabrizio Castro 2019-11-18 21:41 ` [PATCH v4 09/13] dt-bindings: display: bridge: lvds-codec: Document ti,ds90cf384a Rob Herring 2019-11-18 21:41 ` Rob Herring 2019-11-18 21:41 ` Rob Herring 2019-11-19 0:09 ` Laurent Pinchart 2019-11-19 0:09 ` Laurent Pinchart 2019-11-13 15:51 ` [PATCH v4 10/13] ARM: dts: iwg20d-q7-common: Add LCD support Fabrizio Castro 2019-11-13 15:51 ` Fabrizio Castro 2019-11-19 0:10 ` Laurent Pinchart 2019-11-19 0:10 ` Laurent Pinchart 2019-11-25 10:30 ` Geert Uytterhoeven 2019-11-25 10:30 ` Geert Uytterhoeven 2019-11-13 15:51 ` [PATCH v4 11/13] ARM: shmobile_defconfig: Enable support for panels from EDT Fabrizio Castro 2019-11-13 15:51 ` Fabrizio Castro 2019-11-19 0:12 ` Laurent Pinchart 2019-11-19 0:12 ` Laurent Pinchart 2019-11-25 10:30 ` Geert Uytterhoeven 2019-11-25 10:30 ` Geert Uytterhoeven 2019-11-13 15:51 ` [PATCH v4 12/13] [HACK] drm/bridge: lvds-codec: Enforce device specific compatible strings Fabrizio Castro 2019-11-13 15:51 ` Fabrizio Castro 2019-11-19 0:16 ` Laurent Pinchart 2019-11-19 0:16 ` Laurent Pinchart 2019-11-19 11:17 ` Fabrizio Castro 2019-11-19 11:17 ` Fabrizio Castro 2019-11-19 21:51 ` Laurent Pinchart 2019-11-19 21:51 ` Laurent Pinchart 2019-11-21 16:00 ` Fabrizio Castro 2019-11-21 16:00 ` Fabrizio Castro 2019-11-22 8:16 ` Geert Uytterhoeven 2019-11-22 8:16 ` Geert Uytterhoeven 2019-11-25 11:17 ` Fabrizio Castro 2019-11-25 11:17 ` Fabrizio Castro 2019-12-02 9:42 ` Laurent Pinchart 2019-12-02 9:42 ` Laurent Pinchart 2019-11-13 15:51 ` [PATCH v4 13/13] [HACK] dt-bindings: display: bridge: lvds-codec: Absorb thine,thc63lvdm83d.txt Fabrizio Castro 2019-11-13 15:51 ` [PATCH v4 13/13] [HACK] dt-bindings: display: bridge: lvds-codec: Absorb thine, thc63lvdm83d.txt Fabrizio Castro 2019-11-18 21:51 ` [PATCH v4 13/13] [HACK] dt-bindings: display: bridge: lvds-codec: Absorb thine,thc63lvdm83d.txt Rob Herring 2019-11-18 21:51 ` Rob Herring 2019-11-19 0:19 ` Laurent Pinchart 2019-11-19 0:19 ` Laurent Pinchart 2019-12-18 11:52 ` [PATCH v4 00/13] Add LCD panel support to iwg20d Neil Armstrong 2019-12-18 11:52 ` Neil Armstrong 2019-12-18 14:05 ` Fabrizio Castro 2019-12-18 14:05 ` Fabrizio Castro
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