Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1168097AbcKAJXF (ORCPT ); Tue, 1 Nov 2016 05:23:05 -0400 Received: from mail-lf0-f53.google.com ([209.85.215.53]:36350 "EHLO mail-lf0-f53.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1161766AbcKAJXD (ORCPT ); Tue, 1 Nov 2016 05:23:03 -0400 From: Linus Walleij To: lee.jones@linaro.org, linux-kernel@vger.kernel.org Cc: Linus Walleij , stable@vger.kernel.org, Patrice Chotard , Amelie Delaunay Subject: [PATCH] mfd: stmpe: Fix RESET regression on STMPE2401 Date: Tue, 1 Nov 2016 10:22:53 +0100 Message-Id: <1477992173-30964-1-git-send-email-linus.walleij@linaro.org> X-Mailer: git-send-email 2.7.4 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1730 Lines: 49 Since commit c4dd1ba355aae2bc3d1213da6c66c53e3c31e028 ("mfd: stmpe: Add reset support for all STMPE variant") we're resetting the STMPE expanders before use. This caused a regression on the STMP2401 on the Nomadik NHK8815: stmpe-i2c 0-0043: stmpe2401 detected, chip id: 0x101 nmk-i2c 101f8000.i2c0: write to slave 0x43 timed out nmk-i2c 101f8000.i2c0: no ack received after address transmission stmpe-i2c 0-0044: stmpe2401 detected, chip id: 0x101 nmk-i2c 101f8000.i2c0: write to slave 0x44 timed out nmk-i2c 101f8000.i2c0: no ack received after address transmission It turns out that we start to poll for the reset bit to go low again too quickly: the STMPE2401 is not yet online and ready to be asked for the status of the RESET bit. By introducing a 10ms delay before starting to hammer the register for information, we get back to normal: stmpe-i2c 0-0043: stmpe2401 detected, chip id: 0x101 stmpe-i2c 0-0044: stmpe2401 detected, chip id: 0x101 Cc: stable@vger.kernel.org Cc: Patrice Chotard Cc: Amelie Delaunay Cc: Lee Jones Fixes: c4dd1ba355aa ("mfd: stmpe: Add reset support for all STMPE variant") Signed-off-by: Linus Walleij --- drivers/mfd/stmpe.c | 2 ++ 1 file changed, 2 insertions(+) diff --git a/drivers/mfd/stmpe.c b/drivers/mfd/stmpe.c index cfdae8a3d779..b0c7bcdaf5df 100644 --- a/drivers/mfd/stmpe.c +++ b/drivers/mfd/stmpe.c @@ -851,6 +851,8 @@ static int stmpe_reset(struct stmpe *stmpe) if (ret < 0) return ret; + msleep(10); + timeout = jiffies + msecs_to_jiffies(100); while (time_before(jiffies, timeout)) { ret = __stmpe_reg_read(stmpe, stmpe->regs[STMPE_IDX_SYS_CTRL]); -- 2.7.4