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[82.37.195.13]) by smtp.gmail.com with ESMTPSA id 5b1f17b1804b1-499bebfa94esm70641885e9.1.2026.08.24.02.33.18 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Mon, 24 Aug 2026 02:33:18 -0700 (PDT) Date: Mon, 24 Aug 2026 10:33:16 +0100 From: Daniel Thompson To: "A. Sverdlin" Cc: dri-devel@lists.freedesktop.org, linux-fbdev@vger.kernel.org, Andrew Davis , Lee Jones , Pavel Machek , Daniel Thompson , Jingoo Han , Helge Deller , linux-kernel@vger.kernel.org, linux-leds@vger.kernel.org Subject: Re: [PATCH 2/2] leds: lp8864: Register a backlight device Message-ID: References: <20260817170817.1933046-1-alexander.sverdlin@siemens.com> <20260817170817.1933046-3-alexander.sverdlin@siemens.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20260817170817.1933046-3-alexander.sverdlin@siemens.com> X-BeenThere: dri-devel@lists.freedesktop.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: Direct Rendering Infrastructure - Development List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: dri-devel-bounces@lists.freedesktop.org Sender: "dri-devel" On Mon, Aug 17, 2026 at 07:08:15PM +0200, A. Sverdlin wrote: > From: Alexander Sverdlin > > The LP8864/LP8866 is a display-cluster LED backlight driver. Expose a > standard backlight class interface in addition to the LED class device, > so it can be used by display/panel stacks that expect a backlight. > > Use the new devm_led_backlight_register() helper, which spawns a > led-backlight device driven by our LED and tied to the I2C device > lifetime. This keeps the driver a plain LED driver, requires no > device-tree changes and remains backwards compatible with existing DTs. > It is a no-op when the led-backlight support is not enabled. ... but when led-backlight support is enabled it will prohibit the use of the LED sysfs interface. Having zero DT changes is a nice property but it seems rather fragile to change the ABI the userspace must use to manipulate the LED based on CONFIG_LED_BL. Is there no way to explictly configure which ABI should be used? Daniel.