From patchwork Tue Nov 3 20:12:38 2020 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Paul Cercueil X-Patchwork-Id: 11878995 Return-Path: Received: from mail.kernel.org (pdx-korg-mail-1.web.codeaurora.org [172.30.200.123]) by pdx-korg-patchwork-2.web.codeaurora.org (Postfix) with ESMTP id 18FC6921 for ; Tue, 3 Nov 2020 20:20:23 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 0076621556 for ; Tue, 3 Nov 2020 20:20:22 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1728157AbgKCUUW (ORCPT ); Tue, 3 Nov 2020 15:20:22 -0500 Received: from aposti.net ([89.234.176.197]:51606 "EHLO aposti.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1727688AbgKCUUV (ORCPT ); Tue, 3 Nov 2020 15:20:21 -0500 X-Greylist: delayed 450 seconds by postgrey-1.27 at vger.kernel.org; Tue, 03 Nov 2020 15:20:21 EST From: Paul Cercueil To: Jonathan Cameron , Lars-Peter Clausen , Peter Meerwald-Stadler , Artur Rojek Cc: od@zcrc.me, linux-iio@vger.kernel.org, linux-kernel@vger.kernel.org, Paul Cercueil , stable@vger.kernel.org Subject: [PATCH] iio/adc: ingenic: Fix AUX/VBAT readings when touchscreen is used Date: Tue, 3 Nov 2020 20:12:38 +0000 Message-Id: <20201103201238.161083-1-paul@crapouillou.net> MIME-Version: 1.0 Precedence: bulk List-ID: X-Mailing-List: linux-iio@vger.kernel.org When the command feature of the ADC is used, it is possible to program the ADC, and specify at each step what input should be processed, and in comparison to what reference. This broke the AUX and battery readings when the touchscreen was enabled, most likely because the CMD feature would change the VREF all the time. Now, when AUX or battery are read, we temporarily disable the CMD feature, which means that we won't get touchscreen readings in that time frame. But it now gives correct values for AUX / battery, and the touchscreen isn't disabled for long enough to be an actual issue. Fixes: b96952f498db ("IIO: Ingenic JZ47xx: Add touchscreen mode.") Cc: Signed-off-by: Paul Cercueil Acked-by: Artur Rojek --- drivers/iio/adc/ingenic-adc.c | 33 +++++++++++++++++++++++++++------ 1 file changed, 27 insertions(+), 6 deletions(-) diff --git a/drivers/iio/adc/ingenic-adc.c b/drivers/iio/adc/ingenic-adc.c index 92b25083e23f..ecaff6a9b716 100644 --- a/drivers/iio/adc/ingenic-adc.c +++ b/drivers/iio/adc/ingenic-adc.c @@ -177,13 +177,12 @@ static void ingenic_adc_set_config(struct ingenic_adc *adc, mutex_unlock(&adc->lock); } -static void ingenic_adc_enable(struct ingenic_adc *adc, - int engine, - bool enabled) +static void ingenic_adc_enable_unlocked(struct ingenic_adc *adc, + int engine, + bool enabled) { u8 val; - mutex_lock(&adc->lock); val = readb(adc->base + JZ_ADC_REG_ENABLE); if (enabled) @@ -192,20 +191,42 @@ static void ingenic_adc_enable(struct ingenic_adc *adc, val &= ~BIT(engine); writeb(val, adc->base + JZ_ADC_REG_ENABLE); +} + +static void ingenic_adc_enable(struct ingenic_adc *adc, + int engine, + bool enabled) +{ + mutex_lock(&adc->lock); + ingenic_adc_enable_unlocked(adc, engine, enabled); mutex_unlock(&adc->lock); } static int ingenic_adc_capture(struct ingenic_adc *adc, int engine) { + u32 cfg; u8 val; int ret; - ingenic_adc_enable(adc, engine, true); + /* + * Disable CMD_SEL temporarily, because it causes wrong VBAT readings, + * probably due to the switch of VREF. We must keep the lock here to + * avoid races with the buffer enable/disable functions. + */ + mutex_lock(&adc->lock); + cfg = readl(adc->base + JZ_ADC_REG_CFG); + writel(cfg & ~JZ_ADC_REG_CFG_CMD_SEL, adc->base + JZ_ADC_REG_CFG); + + + ingenic_adc_enable_unlocked(adc, engine, true); ret = readb_poll_timeout(adc->base + JZ_ADC_REG_ENABLE, val, !(val & BIT(engine)), 250, 1000); if (ret) - ingenic_adc_enable(adc, engine, false); + ingenic_adc_enable_unlocked(adc, engine, false); + + writel(cfg, adc->base + JZ_ADC_REG_CFG); + mutex_unlock(&adc->lock); return ret; }