From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 16D0838DF1; Mon, 19 Feb 2024 15:13:36 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=10.30.226.201 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1708355617; cv=none; b=rJB/Hw6B73LhWY3DqKWdm9yfFBxCxfTaAjcvvJ1LmoIU3/rC/ZUgn/YxMJ30QRPXmScglQoL4uGN2VM3AUOywZh0ULMvq2qT6tQvsQz0ZKdPeQjflSBpGpXYJqHxxO6EyNMNnaXJs4Suj0OV11aUEZv7i1BYrBV99nKJyQsXALc= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1708355617; c=relaxed/simple; bh=219zpRrF+2txenauOR7oz9BE36nHaUCy6d2FitoCx2g=; h=Date:From:To:Cc:Subject:Message-ID:References:MIME-Version: Content-Type:Content-Disposition:In-Reply-To; b=Un33/SIfdJgxYca46ex/BQk/l8xVkL3dEaQ4Cm25+7l0pf8X3yYBNjeD02xdc3jSmSDxv/TH2q0qbjdnhm75sw1NplPR5b86ujeHQFsloIbJhQSLnoZ3SCbQdnrKrBNsd9ZxvaD7acngQBdS45lYygE+OsbRKG85yrPyJcou4OQ= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=tDAZdOuO; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="tDAZdOuO" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 736E5C433F1; Mon, 19 Feb 2024 15:13:35 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1708355616; bh=219zpRrF+2txenauOR7oz9BE36nHaUCy6d2FitoCx2g=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=tDAZdOuOzQIXrMYvVzMiSwZnj/SSGXgZlyHXJanaGcX21G/YeZcUyGlI7YMlPRBtl NQjnemVKek/RrRiTZJKpp//I5w31ZtqYpzk56LJ55uYxZWUrQz/1SzVkPvhC6ve9Eo 9dyH6cP1uqO1g3P7NsLI2302ABSS7ZEnK3rNMtAz5KPaiKMCXc/Lnd/pyLPse+6mFq JGcMNTDVNvuAoGRYlUrSQz1AMnzRn1X7axI/8cyxsJBQ7I0NBuL7wYrDkHvR4a5wil sOOrvhQHIJwdjXA5iuCRqt5gnP5GZtbXI3EYP/y3/rgpM6qKjRRTF+1Hbl8IDSTPgc Nh1nlMtQee6fg== Date: Mon, 19 Feb 2024 15:13:32 +0000 From: Lee Jones To: Chris Packham Cc: Pavel Machek , "linux-leds@vger.kernel.org" , "linux-kernel@vger.kernel.org" Subject: Re: Linux support for a 7 segment LED display Message-ID: <20240219151332.GC10170@google.com> References: <1f598a72-dd9f-4c6c-af7f-29751f84bd23@alliedtelesis.co.nz> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: <1f598a72-dd9f-4c6c-af7f-29751f84bd23@alliedtelesis.co.nz> On Sun, 11 Feb 2024, Chris Packham wrote: > Hi Blinkenlight enthusiasts, > > I'm looking for something that I figured must exists but maybe it's so > niche that no-one has bothered to upstream a driver for it. > > I have a requirement to support a 7-segment LED display[1] (one that can > display a single digit from 0-9). Hardware wise it's just a bunch of > individual GPIOs connected to each segment (plus an extra one for a > dot). I can't see anything obvious in drivers/leds but maybe I'm looking > in the wrong place. Or maybe it's the kind of thing on PC hardware that > is just driven by the BIOS without the operating system knowing about it. > > Is there an existing in-kernel driver for such a thing? Why would LEDs connected to a bunch of GPIOs in a specific fashion require a hardware driver? Doesn't drivers/leds/leds-gpio.c already provide all the support you need? -- Lee Jones [李琼斯]