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 08BC632721F; Wed, 26 Nov 2025 12:33:42 +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=1764160423; cv=none; b=fVdYb6yJcesxXQztdrFHdCHwlm+iD/AxPMklhjjUdSnuH7kpznNqFIiXDw2eKTISTTCutFCsCG98cBgohe9+MntkQm41dBbtnWb7NVqSXcCTWMqf8t9gyx3BZfnbOfCAgy2teqxy8kSUzekHcvnXlciA6t26mJnRmL6pVfnpzsM= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1764160423; c=relaxed/simple; bh=WlUVaShN9mH14jqFXquyf1gKUl8dks8bpJbxLKEl6qk=; h=Date:From:To:Cc:Subject:Message-ID:References:MIME-Version: Content-Type:Content-Disposition:In-Reply-To; b=WFCH3gMYb2stkIE7JM8U9eWzjRun+h7XRJ8YwIHH7P872kRFK+4S0d0uHXUqNFui/2HipKsSNChnHRY0M8yB9gRw5c8nNAcDy7C+nKURxsHaSBw1aIgWEuGjBw/r5iS7rkD1262LQSIc91lHF6aTcRELWzCS02W1fdLas3MeQx4= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=s2r7N7ky; 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="s2r7N7ky" Received: by smtp.kernel.org (Postfix) with ESMTPSA id EF495C113D0; Wed, 26 Nov 2025 12:33:40 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1764160422; bh=WlUVaShN9mH14jqFXquyf1gKUl8dks8bpJbxLKEl6qk=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=s2r7N7kyyi4co3v569XomNC7tcLFiWTQdGkehyrtCqFmicHOw0ojaoMcAHVK/sd1s 5Oyd0Uquzy4MoCNJkS4O8kNhdTSehll91vqyB9mmQVBdTFHsbeYu7BZaWpQVVAJbqf uYATE4Uug2cXlv3wWzMuWWfPmzMwg8bPKS986x2tRYh71EW0kbSWHl9GUU/9UKo8zI CqJYXb/o4ToCrPTGZ8ZaWjDZKlQnrlYq0LHlcfyklJHSufAv5987qW90EsR9QZZKFL 52yulW8Ocv0nNrhjkJ9HTj5ku1V5isCBR2c6XT5JflD/8vXwK42c1zTqA6EJWhXp49 Mf2xT7MeHUHtg== Date: Wed, 26 Nov 2025 12:33:38 +0000 From: Daniel Thompson To: petri.karhula@novatron.fi Cc: Thomas Richard , Lee Jones , Jingoo Han , Helge Deller , linux-kernel@vger.kernel.org, dri-devel@lists.freedesktop.org, linux-fbdev@vger.kernel.org Subject: Re: [PATCH v3 1/2] backlight: Add Congatec Board Controller (CGBC) backlight support Message-ID: References: <20251125-cgbc-backlight-v3-0-18ae42689411@novatron.fi> <20251125-cgbc-backlight-v3-1-18ae42689411@novatron.fi> Precedence: bulk X-Mailing-List: linux-fbdev@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20251125-cgbc-backlight-v3-1-18ae42689411@novatron.fi> On Tue, Nov 25, 2025 at 03:29:39PM +0000, Petri Karhula via B4 Relay wrote: > From: Petri Karhula > > This driver provides backlight brightness control through the Linux > backlight subsystem. It communicates with the board controller to > adjust LCD backlight using PWM signals. Communication is done > through Congatec Board Controller core driver. > > Signed-off-by: Petri Karhula > --- > drivers/video/backlight/Kconfig | 11 +++ > drivers/video/backlight/Makefile | 1 + > drivers/video/backlight/cgbc_bl.c | 177 ++++++++++++++++++++++++++++++++++++++ > 3 files changed, 189 insertions(+) > +static int cgbc_bl_probe(struct platform_device *pdev) > +{ > + struct cgbc_device_data *cgbc = dev_get_drvdata(pdev->dev.parent); > + struct backlight_properties props = { }; > + u8 cmd_buf[4] = { CGBC_CMD_BLT0_PWM }; > + struct backlight_device *bl_dev; > + struct cgbc_bl_data *bl_data; > + u8 reply_buf[3]; > + int ret; > + > + bl_data = devm_kzalloc(&pdev->dev, sizeof(*bl_data), GFP_KERNEL); > + if (!bl_data) > + return -ENOMEM; > + > + bl_data->dev = &pdev->dev; > + bl_data->cgbc = cgbc; > + > + ret = cgbc_command(bl_data->cgbc, cmd_buf, sizeof(cmd_buf), reply_buf, > + sizeof(reply_buf), NULL); > + if (ret < 0) > + return dev_err_probe(&pdev->dev, ret, > + "Failed to read initial brightness\n"); > + > + /* > + * Get only PWM duty factor percentage, > + * ignore polarity inversion bit (bit 7) > + */ > + bl_data->current_brightness = FIELD_GET(BLT_PWM_DUTY_MASK, reply_buf[0]); It would good to common this up with cgbc_bl_get_brightness() by providing a helper that takes struct cgbc_bl_data * and calling it from both places. > + > + props.type = BACKLIGHT_PLATFORM; > + props.max_brightness = CGBC_BL_MAX_BRIGHTNESS; > + props.brightness = bl_data->current_brightness; New drivers should always set props.scale . > + > + bl_dev = devm_backlight_device_register(&pdev->dev, "cgbc-backlight", > + &pdev->dev, bl_data, > + &cgbc_bl_ops, &props); > + if (IS_ERR(bl_dev)) > + return dev_err_probe(&pdev->dev, PTR_ERR(bl_dev), > + "Failed to register backlight device\n"); > + > + platform_set_drvdata(pdev, bl_data); > + > + return 0; > +} > + > +static struct platform_driver cgbc_bl_driver = { > + .driver = { > + .name = "cgbc-backlight", > + }, > + .probe = cgbc_bl_probe, > +}; Daniel.