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[2620:137:e000::1:20]) by mx.google.com with ESMTP id n1-20020a63b441000000b00438b79bcf26si1948170pgu.151.2022.11.17.12.54.45; Thu, 17 Nov 2022 12:54:59 -0800 (PST) Received-SPF: pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 2620:137:e000::1:20 as permitted sender) client-ip=2620:137:e000::1:20; Authentication-Results: mx.google.com; dkim=pass header.i=@chromium.org header.s=google header.b=jZE6ECZl; spf=pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 2620:137:e000::1:20 as permitted sender) smtp.mailfrom=linux-kernel-owner@vger.kernel.org; dmarc=pass (p=NONE sp=NONE dis=NONE) header.from=chromium.org Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S234948AbiKQUio (ORCPT + 99 others); Thu, 17 Nov 2022 15:38:44 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:39226 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S231146AbiKQUim (ORCPT ); Thu, 17 Nov 2022 15:38:42 -0500 Received: from mail-pl1-x636.google.com (mail-pl1-x636.google.com [IPv6:2607:f8b0:4864:20::636]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 593C01181E for ; Thu, 17 Nov 2022 12:38:41 -0800 (PST) Received: by mail-pl1-x636.google.com with SMTP id 4so2751591pli.0 for ; Thu, 17 Nov 2022 12:38:41 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=chromium.org; s=google; h=content-transfer-encoding:mime-version:message-id:date:subject:cc :to:from:from:to:cc:subject:date:message-id:reply-to; bh=SjvIvcadXOdk0//s0f5eSqUtPjdovzzs9vUSgPGddUo=; b=jZE6ECZl1zk5iL/4nuf8rhLihmew/+6DR2bHWgiQLbe6aB6lY3Ow3KvwuaNEdu2BqS aR2IVDA0gmcJ/rw3ia8R4/DPc/h3cZCIaq7gKtxISFwxyMD3kvdb3Dngu9UgY5uhWiUx vn3NiEesBU5P1w3wchxgr56v74ym5NjREJGko= X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; h=content-transfer-encoding:mime-version:message-id:date:subject:cc :to:from:x-gm-message-state:from:to:cc:subject:date:message-id :reply-to; bh=SjvIvcadXOdk0//s0f5eSqUtPjdovzzs9vUSgPGddUo=; b=e1H62PTefDC0hU5LmVqWZ4+UhM6pl9spBbFhttn2QEciYwL/Jb5wRyvYturaayK40B 6U0Ak6Ocayfdn7kwwgksF90NaOZ07fxtzHb4ibLjNcDfUvG76rFtqoShwNN3rrA84Tk5 nLycFGwLD/LknNTebrCjsYb8fhaay/7rTHHYV7qTHf81nrwx+GEGE5h/iSDMVUSka/PH AtUMfP2dYsYR/aN9AcQtQlA0FoHiXiRFRqBIR3BGVuQ7FQEeZlGxi/UC/LNMX+DU+qYp afo9/2YSGSlSDPZLEtJXT5Fo0yPlEh5L2tnR8LMmFYTK9VLF+BvzHs8i8eYNHNYmiWZr oT9g== X-Gm-Message-State: ANoB5pnpXXNNw4m0MY5fuORV9H+qIrd3Sh0yCuvYFGNysXrDpw4klwMJ B7XFNz1bn478Ba9brFjR1H98sA== X-Received: by 2002:a17:903:2448:b0:188:f5c7:4d23 with SMTP id l8-20020a170903244800b00188f5c74d23mr2718635pls.125.1668717520846; Thu, 17 Nov 2022 12:38:40 -0800 (PST) Received: from tictac2.mtv.corp.google.com ([2620:15c:9d:2:6069:1273:e67f:93a3]) by smtp.gmail.com with ESMTPSA id 185-20020a6214c2000000b005618189b0ffsm1578091pfu.104.2022.11.17.12.38.39 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Thu, 17 Nov 2022 12:38:40 -0800 (PST) From: Douglas Anderson To: Dmitry Torokhov Cc: Douglas Anderson , Benson Leung , Johnny Chuang , Scott Liu , linux-input@vger.kernel.org, linux-kernel@vger.kernel.org Subject: [PATCH] Input: elants_i2c: Properly handle the reset GPIO when power is off Date: Thu, 17 Nov 2022 12:38:23 -0800 Message-Id: <20221117123805.1.I9959ac561dd6e1e8e1ce7085e4de6167b27c574f@changeid> X-Mailer: git-send-email 2.38.1.584.g0f3c55d4c2-goog MIME-Version: 1.0 X-Spam-Status: No, score=-2.1 required=5.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,DKIM_VALID_EF,RCVD_IN_DNSWL_NONE, SPF_HELO_NONE,SPF_PASS autolearn=unavailable autolearn_force=no version=3.4.6 X-Spam-Checker-Version: SpamAssassin 3.4.6 (2021-04-09) on lindbergh.monkeyblade.net Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org X-getmail-retrieved-from-mailbox: =?utf-8?q?INBOX?= X-GMAIL-THRID: =?utf-8?q?1749778169855449986?= X-GMAIL-MSGID: =?utf-8?q?1749778169855449986?= As can be seen in elants_i2c_power_off(), we want the reset GPIO asserted when power is off. The reset GPIO is active low so we need the reset line logic low when power is off to avoid leakage. We have a problem, though, at probe time. At probe time we haven't powered the regulators on yet but we have: devm_gpiod_get(&client->dev, "reset", GPIOD_OUT_LOW); While that _looks_ right, it turns out that it's not. The GPIOD_OUT_LOW doesn't mean to init the GPIO to low. It means init the GPIO to "not asserted". Since this is an active low GPIO that inits it to be high. Let's fix this to properly init the GPIO. Now after both probe and power off the state of the GPIO is consistent (it's "asserted" or level low). Once we fix this, we can see that at power on time we no longer to assert the reset GPIO as the first thing. The reset GPIO is _always_ asserted before powering on. Let's fix powering on to account for this. Fixes: afe10358e47a ("Input: elants_i2c - wire up regulator support") Signed-off-by: Douglas Anderson --- This issue was found mostly due to code inspection. A partner was having issues with power sequencing with this touch screen and I noticed this issue in the code. Though this patch doesn't seem to fully address the problems that the partner was having (they are still debugging), in the very least it seems correct and we should probably take it. This problem has been around for a while. Presumably the touchscreen is tolerant enough to this short period of time at bootup where the reset line was leaking power into the unpowered touchscreen, though it's still not great. drivers/input/touchscreen/elants_i2c.c | 9 +++------ 1 file changed, 3 insertions(+), 6 deletions(-) diff --git a/drivers/input/touchscreen/elants_i2c.c b/drivers/input/touchscreen/elants_i2c.c index 879a4d984c90..e1308e179dd6 100644 --- a/drivers/input/touchscreen/elants_i2c.c +++ b/drivers/input/touchscreen/elants_i2c.c @@ -1329,14 +1329,12 @@ static int elants_i2c_power_on(struct elants_data *ts) if (IS_ERR_OR_NULL(ts->reset_gpio)) return 0; - gpiod_set_value_cansleep(ts->reset_gpio, 1); - error = regulator_enable(ts->vcc33); if (error) { dev_err(&ts->client->dev, "failed to enable vcc33 regulator: %d\n", error); - goto release_reset_gpio; + return error; } error = regulator_enable(ts->vccio); @@ -1345,7 +1343,7 @@ static int elants_i2c_power_on(struct elants_data *ts) "failed to enable vccio regulator: %d\n", error); regulator_disable(ts->vcc33); - goto release_reset_gpio; + return error; } /* @@ -1354,7 +1352,6 @@ static int elants_i2c_power_on(struct elants_data *ts) */ udelay(ELAN_POWERON_DELAY_USEC); -release_reset_gpio: gpiod_set_value_cansleep(ts->reset_gpio, 0); if (error) return error; @@ -1462,7 +1459,7 @@ static int elants_i2c_probe(struct i2c_client *client) return error; } - ts->reset_gpio = devm_gpiod_get(&client->dev, "reset", GPIOD_OUT_LOW); + ts->reset_gpio = devm_gpiod_get(&client->dev, "reset", GPIOD_OUT_HIGH); if (IS_ERR(ts->reset_gpio)) { error = PTR_ERR(ts->reset_gpio);