[PATCH 0/4] Fix common issue in MAX* extcon drivers

From: Marek Szyprowski <m.szyprowski@samsung.com>
To: linux-kernel@vger.kernel.org, linux-samsung-soc@vger.kernel.org
Cc: Marek Szyprowski <m.szyprowski@samsung.com>,
	MyungJoo Ham <myungjoo.ham@samsung.com>,
	Chanwoo Choi <cw00.choi@samsung.com>,
	Krzysztof Kozlowski <krzk@kernel.org>,
	Bartlomiej Zolnierkiewicz <b.zolnierkie@samsung.com>
Subject: [PATCH 0/4] Fix common issue in MAX* extcon drivers
Date: Thu, 08 Nov 2018 14:45:44 +0100	[thread overview]
Message-ID: <20181108134548.31140-1-m.szyprowski@samsung.com> (raw)
In-Reply-To: CGME20181108134553eucas1p1a513f538b74fab263c3f143914d30720@eucas1p1.samsung.com

Hi All

Most MAX* MUIC drivers unconditionally force UART path during probe.
This approach causes some issues, especially when board is booted with
non-UART cable connected to micro-USB port. For example, when USB cable is
connected, UART TX/RX lines are unconditionally short-circuited to USB
D+/D- lines. This is in turn recognized by a series of serial BREAK
signals and some random characters when USB host tries to perform
enumeration procedure.

To solve the above issue and keep UART console operational as early as
possible, set UART path only when USB ID reports UART capable cable.

This patchset fixes following MAX* extcon drivers: 8997, 14577, 77693
and 77843.

Tested on following Samsung boards: Trats (8997), Rinato (14577), Trats2
(77693) and TM2/TM2e (77843).

Best regards
Marek Szyprowski
Samsung R&D Institute Poland

Patch summary:

Marek Szyprowski (4):
  extcon: max77843: Avoid forcing UART path on drive probe
  extcon: max77693: Avoid forcing UART path on drive probe
  extcon: max14577: Avoid forcing UART path on drive probe
  extcon: max8997: Avoid forcing UART path on drive probe

 drivers/extcon/extcon-max14577.c | 15 +++++++++++++--
 drivers/extcon/extcon-max77693.c | 16 ++++++++++++++--
 drivers/extcon/extcon-max77843.c | 18 +++++++++++++++---
 drivers/extcon/extcon-max8997.c  | 15 +++++++++++++--
 4 files changed, 55 insertions(+), 9 deletions(-)

-- 
2.17.1