From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752848AbdIIXA5 (ORCPT ); Sat, 9 Sep 2017 19:00:57 -0400 Received: from shadbolt.e.decadent.org.uk ([88.96.1.126]:43076 "EHLO shadbolt.e.decadent.org.uk" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752849AbdIIXAy (ORCPT ); Sat, 9 Sep 2017 19:00:54 -0400 Content-Type: text/plain; charset="UTF-8" Content-Disposition: inline Content-Transfer-Encoding: 8bit MIME-Version: 1.0 From: Ben Hutchings To: linux-kernel@vger.kernel.org, stable@vger.kernel.org CC: akpm@linux-foundation.org, "Linus Walleij" , "=?UTF-8?q?Uwe=20Kleine-K=C3=B6nig?=" , "Shawn Guo" Date: Sat, 09 Sep 2017 22:47:14 +0100 Message-ID: X-Mailer: LinuxStableQueue (scripts by bwh) Subject: [PATCH 3.16 081/233] pinctrl: mxs: atomically switch mux and drive strength config In-Reply-To: X-SA-Exim-Connect-IP: 2a02:8011:400e:2:6f00:88c8:c921:d332 X-SA-Exim-Mail-From: ben@decadent.org.uk X-SA-Exim-Scanned: No (on shadbolt.decadent.org.uk); SAEximRunCond expanded to false Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 3.16.48-rc1 review patch. If anyone has any objections, please let me know. ------------------ From: Uwe Kleine-König commit da6c2addf66d7ff7d0b090d6267d4292f951e4e6 upstream. To set the mux mode of a pin two bits must be set. Up to now this is implemented using the following idiom: writel(mask, reg + CLR); writel(value, reg + SET); . This however results in the mux mode being 0 between the two writes. On my machine there is an IC's reset pin connected to LCD_D20. The bootloader configures this pin as GPIO output-high (i.e. not holding the IC in reset). When Linux reconfigures the pin to GPIO the short time LCD_D20 is muxed as LCD_D20 instead of GPIO_1_20 is enough to confuse the connected IC. The same problem is present for the pin's drive strength setting which is reset to low drive strength before using the right value. So instead of relying on the hardware to modify the register setting using two writes implement the bit toggling using read-modify-write. Fixes: 17723111e64f ("pinctrl: add pinctrl-mxs support") Signed-off-by: Uwe Kleine-König Acked-by: Shawn Guo Signed-off-by: Linus Walleij [bwh: Backported to 3.16: adjust filename, context] Signed-off-by: Ben Hutchings --- drivers/pinctrl/pinctrl-mxs.c | 16 ++++++++++++---- 1 file changed, 12 insertions(+), 4 deletions(-) --- a/drivers/pinctrl/pinctrl-mxs.c +++ b/drivers/pinctrl/pinctrl-mxs.c @@ -195,6 +195,16 @@ static int mxs_pinctrl_get_func_groups(s return 0; } +static void mxs_pinctrl_rmwl(u32 value, u32 mask, u8 shift, void __iomem *reg) +{ + u32 tmp; + + tmp = readl(reg); + tmp &= ~(mask << shift); + tmp |= value << shift; + writel(tmp, reg); +} + static int mxs_pinctrl_enable(struct pinctrl_dev *pctldev, unsigned selector, unsigned group) { @@ -212,8 +222,7 @@ static int mxs_pinctrl_enable(struct pin reg += bank * 0x20 + pin / 16 * 0x10; shift = pin % 16 * 2; - writel(0x3 << shift, reg + CLR); - writel(g->muxsel[i] << shift, reg + SET); + mxs_pinctrl_rmwl(g->muxsel[i], 0x3, shift, reg); } return 0; @@ -280,8 +289,7 @@ static int mxs_pinconf_group_set(struct /* mA */ if (config & MA_PRESENT) { shift = pin % 8 * 4; - writel(0x3 << shift, reg + CLR); - writel(ma << shift, reg + SET); + mxs_pinctrl_rmwl(ma, 0x3, shift, reg); } /* vol */