From patchwork Wed Apr 17 15:31:04 2024 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Flavio Suligoi X-Patchwork-Id: 13633545 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from gabe.freedesktop.org (gabe.freedesktop.org [131.252.210.177]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.lore.kernel.org (Postfix) with ESMTPS id DE2A3C001CC for ; Wed, 17 Apr 2024 15:46:23 +0000 (UTC) Received: from gabe.freedesktop.org (localhost [127.0.0.1]) by gabe.freedesktop.org (Postfix) with ESMTP id 16DB111363D; Wed, 17 Apr 2024 15:46:23 +0000 (UTC) Authentication-Results: gabe.freedesktop.org; dkim=fail reason="signature verification failed" (2048-bit key; unprotected) header.d=smtpcorp.com header.i=@smtpcorp.com header.b="eSeXQ/2W"; dkim=pass (2048-bit key; unprotected) header.d=asem.it header.i=@asem.it header.b="dKnn8c04"; dkim-atps=neutral X-Greylist: delayed 902 seconds by postgrey-1.36 at gabe; Wed, 17 Apr 2024 15:46:19 UTC Received: from e3i51.smtp2go.com (e3i51.smtp2go.com [158.120.84.51]) by gabe.freedesktop.org (Postfix) with ESMTPS id BFBCF11363D for ; Wed, 17 Apr 2024 15:46:19 +0000 (UTC) Received: from [10.86.249.198] (helo=asas054.asem.intra) by smtpcorp.com with esmtpa (Exim 4.96.1-S2G) (envelope-from ) id 1rx7Fg-g2w585-0j for dri-devel@lists.freedesktop.org; Wed, 17 Apr 2024 15:31:12 +0000 Received: from flavio-x.asem.intra ([172.16.18.47]) by asas054.asem.intra with Microsoft SMTPSVC(10.0.14393.4169); Wed, 17 Apr 2024 17:31:10 +0200 From: Flavio Suligoi To: Lee Jones , Daniel Thompson , Jingoo Han , Helge Deller , Dan Carpenter Cc: dri-devel@lists.freedesktop.org, linux-fbdev@vger.kernel.org, linux-kernel@vger.kernel.org, Flavio Suligoi Subject: [PATCH v1 0/1] backlight: mp3309c: fix leds flickering in pwm mode Date: Wed, 17 Apr 2024 17:31:04 +0200 Message-Id: <20240417153105.1794134-1-f.suligoi@asem.it> X-Mailer: git-send-email 2.34.1 MIME-Version: 1.0 X-OriginalArrivalTime: 17 Apr 2024 15:31:10.0467 (UTC) FILETIME=[4621B530:01DA90DC] X-smtpcorp-track: 1rx7Fgg2w5850M.HztUDgdIVRjKa DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=smtpcorp.com; i=@smtpcorp.com; q=dns/txt; s=a1-4; t=1713367874; h=feedback-id : x-smtpcorp-track : date : message-id : to : subject : from : reply-to : sender : list-unsubscribe; bh=krcOgqXsGe7x+1M7PzgJWjOituJS8hooQQYOs5GAeeo=; b=eSeXQ/2Wmck1NpS88BM4fOtUsGzHEaegOZfk1LK14X4z05BUxtoaaIovukQPjwAZF8HAn 146JN5Asxr0b6j7l5XvHhx+g7vjm24ThYnsAey+dogkNs/VEuB9doV2wgGBwlusALF6jwMc bPGUv3dYDn8/l293dZrzDsyT9nZYF6K5ovkrrDdzOp21VQei2mIHawfbTQcEwveYZUKMpje h/beFnI9/hSkil0WFL17jsB66VgmPFfiKDTIqBFvjJtJlM++U4zCGScSDdfE/NVvrAvSSup YllSusF6gCE2Pi6oUnSSwjHq7RW/iV5rnN9kmRuwdnGkWB6fu+Qb62KTB9ug== DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=asem.it; i=@asem.it; q=dns/txt; s=s1174574; t=1713367874; h=from : subject : to : message-id : date; bh=krcOgqXsGe7x+1M7PzgJWjOituJS8hooQQYOs5GAeeo=; b=dKnn8c04Pb0OQdeecLKZQxnnthStE8ighfdrx+VQ6GaNf1BEY4eIbgfXEH0vtKcwVtRSI 1EKUIcTSZCyitv2ds1QeOhhKEmGgxtRAxCe7MZy8EPD3tInMtKpu34AArfoqk3W0ZzRv4PG EYn75vewSDpNRyZ6uMo5ZFBx0v9qalaO1ks9ZZr+WdJYN5tZqIjC9vxJ5gbJ50c45Nn736h cRvEhjDdwa9H7CR1p7gLc2TzUZJvjH2ou3AIlcF3+qdEytDO2U0afGjfP9dQ7HIPEQXx9bk HlFmKAVAhXBnBdsdSYQIZLNdrsoB7cnR92cc+nEQ17+sqvtxjp8an3mEzGpg== 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" The mp3309 has two configuration registers, named according to their address (0x00 and 0x01). In the second register (0x01), the bit DIMS (Dimming Mode Select) must be always 0 (zero), in both analog (via i2c commands) and pwm dimming mode. In the initial driver version, the DIMS bit was set in pwm mode and reset in analog mode. But if the DIMS bit is set in pwm dimming mode and other devices are connected on the same i2c bus, every i2c commands on the bus generates a flickering on the LEDs powered by the mp3309c. This change concerns the chip initialization and does not impact any existing device-tree configuration. I created this device driver for one of our boards, where both dimming modes (pwm and analog by i2c commands) can be used. This board uses the same i2c bus for the mp3309c and for an at24cs32 eeprom. During further tests, I realized that, when the mp3309c is used in pwm mode, every read operation on the eeprom caused a backlight flickering. This is why I made this device driver modification. Flavio Suligoi (1): backlight: mp3309c: fix leds flickering in pwm mode drivers/video/backlight/mp3309c.c | 5 ----- 1 file changed, 5 deletions(-)