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: 790003 Received: from e3i51.smtp2go.com (e3i51.smtp2go.com [158.120.84.51]) (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 E5CCB147C68 for ; Wed, 17 Apr 2024 15:31:19 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=158.120.84.51 ARC-Seal: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1713367881; cv=none; b=ITQRWaWavL9cyW2s6NkIctcGyiyUlJLiaEeUxlrT3Scu0ianQqSYpR5vjQ6Q1FBl+4hEcXKk2dKNcRAlvdebyqSK+XRnrlud/wxyQgX1Bsw7FGxgJxEL2zaZixdXUWTKD0umRPgk6hNqk+7W5qUK11JE3Z8cHFaQFaYJRdjW2d0= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1713367881; c=relaxed/simple; bh=dgCz2SWncqiO+Q6bWQmQ5trn7DREaGzNKuFcjXqMQKk=; h=From:To:Cc:Subject:Date:Message-Id:MIME-Version; b=tXFysn8Iv7rpBTp8V4zwMN+S3cx1RWwr4/3iDXa7NBnBrE1Md21goXiBaVHCYBIwa3ERtPgKkY8qFKIrzdWNxp1yGwM1vIie7fXVIu4Gbr72Jqkz09fQoSliBGR0zBxrXGdPznaJAuXThSukXvcWjHHvAjv/PkmXaKge6oE36Co= ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=asem.it; spf=pass smtp.mailfrom=em1174574.asem.it; dkim=pass (2048-bit key) header.d=smtpcorp.com header.i=@smtpcorp.com header.b=LeQsxAV4; dkim=pass (2048-bit key) header.d=asem.it header.i=@asem.it header.b=SaZWuFhR; arc=none smtp.client-ip=158.120.84.51 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=asem.it Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=em1174574.asem.it Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=smtpcorp.com header.i=@smtpcorp.com header.b="LeQsxAV4"; dkim=pass (2048-bit key) header.d=asem.it header.i=@asem.it header.b="SaZWuFhR" Received: from [10.86.249.198] (helo=asas054.asem.intra) by smtpcorp.com with esmtpa (Exim 4.96.1-S2G) (envelope-from ) id 1rx7Fg-Dv6PUh-0c; 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 Precedence: bulk X-Mailing-List: linux-fbdev@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 X-OriginalArrivalTime: 17 Apr 2024 15:31:10.0467 (UTC) FILETIME=[4621B530:01DA90DC] X-smtpcorp-track: 1rx7FgDv6elh0c.HztUDgdIOQXm6 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=smtpcorp.com; i=@smtpcorp.com; q=dns/txt; s=a1-4; t=1713367875; h=feedback-id : x-smtpcorp-track : date : message-id : to : subject : from : reply-to : sender : list-unsubscribe; bh=krcOgqXsGe7x+1M7PzgJWjOituJS8hooQQYOs5GAeeo=; b=LeQsxAV4FEJVXr0/X90DLNVSjjT9O+KK74/V2X7YihR6rcWUBQKuTuiCI35UidbhTEhUf ntp3VBWtabCByCvr01w2KTya+R7jxd2hzve+NWvbPMFL980ZlClqQoEYWEtL6My5KVRlqqs qXglu2n5Fhq8HEqVw/vBU8IFLHiETHi9EBPeuzpq8Kzrkwyn3gJcYL5MjIlLXBtebTZOdSc vpvuZpETlxV+u7ZZpI4kfFuYFYLe17F04mNmtDkiV2LdTqYTQi0sBW/FZw9d0RG48BDIRXj BHrO4fELPXgjIrUe3nXm9dY366xoRbPH3MMeiBt7ZRjo8QRDobrYOzrp2YrQ== DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=asem.it; i=@asem.it; q=dns/txt; s=s1174574; t=1713367875; h=from : subject : to : message-id : date; bh=krcOgqXsGe7x+1M7PzgJWjOituJS8hooQQYOs5GAeeo=; b=SaZWuFhRRDRQH7WyFm9OKqiEnaeAHC7T8yIk2sTX5X5rLjPFt2gwhcnNCmo/ug8bCj8/0 rJVd1Ah1r5DqSqo2NG0GeFfiuKRijIFfAdBZKaXSKMIGb/oF1eY/TeZAi4IMRCKKrdtA+43 WMmjI+Km5vHM8UbtJ2D1tGTbRATiPXJaSX34qNbCGFvWV8KaRfs0AtvL5NweKYO5u+kaGj0 oDUQvozeMXF7TJn2nxDo7sFuD3VnCSFrVVEPfDXmxOVLJ5OK7XVn4ZHVlnu16yV7X2WLLP2 ZeejHFetuezYk5vFfPh4Q97OTSD8S1CR3Dvf+bbsi3wI591unWzGqXbQBfAQ== 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(-)