From: "Luca Ceresoli" <luca.ceresoli@bootlin.com>
To: "Sean Chang" <seanwascoding@gmail.com>,
"Andrzej Hajda" <andrzej.hajda@intel.com>,
"Neil Armstrong" <neil.armstrong@linaro.org>,
"Robert Foss" <rfoss@kernel.org>,
"Maarten Lankhorst" <maarten.lankhorst@linux.intel.com>,
"Maxime Ripard" <mripard@kernel.org>,
"Thomas Zimmermann" <tzimmermann@suse.de>,
"David Airlie" <airlied@gmail.com>,
"Simona Vetter" <simona@ffwll.ch>
Cc: "Laurent Pinchart" <Laurent.pinchart@ideasonboard.com>,
"Jonas Karlman" <jonas@kwiboo.se>,
"Jernej Skrabec" <jernej.skrabec@gmail.com>,
"Luca Ceresoli" <luca.ceresoli@bootlin.com>,
"Liu Ying" <victor.liu@nxp.com>,
"Jani Nikula" <jani.nikula@intel.com>,
"Shengjiu Wang" <shengjiu.wang@nxp.com>,
"Javier Martinez Canillas" <javierm@redhat.com>,
<dri-devel@lists.freedesktop.org>, <linux-kernel@vger.kernel.org>
Subject: Re: [PATCH v1] drm: bridge: dw_hdmi: Fix constant truncation warning on phy_mask
Date: Tue, 25 Aug 2026 12:29:29 +0200 [thread overview]
Message-ID: <DKXYDGIP3KRX.3AJ5KBX7VI2M7@bootlin.com> (raw)
In-Reply-To: <20260819151216.56833-1-seanwascoding@gmail.com>
On Wed Aug 19, 2026 at 5:12 PM CEST, Sean Chang wrote:
> In dw_hdmi_probe(), casting the bitwise complement of (HDMI_PHY_HPD |
> HDMI_PHY_RX_SENSE) directly to u8 triggers a compiler warning
> (-Wconstant-conversion).
>
> Due to C integer promotion rules, the bitwise OR and bitwise NOT are
> evaluated as 32-bit signed integers, producing 0xFFFFFF0D before being
> cast down to u8.
>
> Fix this by explicitly masking the inverted 32-bit result with 0xFF
> to keep only the lower byte and prevent implicit upper-bit truncation.
>
> Signed-off-by: Sean Chang <seanwascoding@gmail.com>
Reviewed-by: Luca Ceresoli <luca.ceresoli@bootlin.com>
--
Luca Ceresoli, Bootlin
Embedded Linux and Kernel engineering
https://bootlin.com
prev parent reply other threads:[~2026-08-25 10:29 UTC|newest]
Thread overview: 2+ messages / expand[flat|nested] mbox.gz Atom feed top
2026-08-19 15:12 [PATCH v1] drm: bridge: dw_hdmi: Fix constant truncation warning on phy_mask Sean Chang
2026-08-25 10:29 ` Luca Ceresoli [this message]
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