From mboxrd@z Thu Jan 1 00:00:00 1970 Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.remote-ip=194.117.254.33 ARC-Seal: i=1; d=subspace.kernel.org; s=arc20261015; a=rsa-sha256; cv=none; t=1794306288; b=zI9iUcDM/ig/oelDb2ZgC7gkAUzQJsGTGr2Q37YDruYUT0LpqbFWp2bX8x9nVrCkhVRX dbyOcY/aaPvTOvnM7pXbGh63rSR7g2kCeDG3wb34SKflqDuK2+fOT1JQP90J5Zl3UBZpb BpsQaGZSVzZwk+26kdrn1vXMjNrD+5Wr2QT5s9TUoyLQ4ajAn/s4HGaBkvPeXMKSnm0bU OtEDOkE5gFlBnKOkXHMDmrpRjz7Ux6hXmdPHJSm0AodxKDPtSy4tbr+rzMGCa108undSS gQIFHMm2RTJY1NDGZY5ZKURvepWyv0uOYvWfPkg2+fCOHmZX31u5HInomjOc0ThVIkA== ARC-Message-Signature: i=1; d=subspace.kernel.org; s=arc20261015; a=rsa-sha256; c=relaxed/relaxed; t=1794306288; h=DMARC-Filter:DKIM-Signature:Received:Received:X-UD-Smtp-Session:Date: From:To:Cc:Subject:Message-ID:References:MIME-Version:Content-Type: Content-Disposition:In-Reply-To; bh=EhDjNoe3/JC0Wvq34jTb4Txp8C72674LsLZBKo4ri38=; b=EyG6CoTIVfVOMYeEvGP2RUUf+duf6nuvTs9LLXlVSW6aIAPTchv+rWmb1O9xAHzeFHgx QvZyGgDo1amL51lc4F0AqWmMHum8g9yJc8xf96+7VPWAxHJW4wcvtJP8cmjBv8EaQZaKI dnCMKp7GCE/mps/GrDe5tGkxi5rAi6SUeL1aHXe5q+kn9ktUYiFVWQjKXv+ndi//6QyVI xiHM1HADpzSlH8gyyvdDrD5Dd1eLnEwcafWydJGVdvBscKVzV0rk+sq04NsD6eW/GmgNc /2Oo9DSsN5diVLr9y6EY2aCsMDaGt8jW09dqwfIQNRVcs7Mzzj7PmJj6hwMQrZTB9pA== ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dmarc=none header.from=sang-engineering.com; spf=pass smtp.mailfrom=sang-engineering.com; dkim=pass header.d=sang-engineering.com header.i=@sang-engineering.com header.a=rsa-sha256 header.s=k1 header.b=TNCFRS9K; arc=none smtp.remote-ip=194.117.254.33 Received: from mail.zeus03.de (zeus03.de [194.117.254.33]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature ECDSA (prime256v1) server-digest SHA256) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id E35C6606DE19 for ; Tue, 10 Nov 2026 10:24:46 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.4.2 smtp.subspace.kernel.org E35C6606DE19 Authentication-Results: smtp.subspace.kernel.org; dmarc=none (p=none dis=none) header.from=sang-engineering.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=sang-engineering.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key, unprotected) header.d=sang-engineering.com header.i=@sang-engineering.com header.a=rsa-sha256 header.s=k1 header.b=TNCFRS9K DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d= sang-engineering.com; h=date:from:to:cc:subject:message-id :references:mime-version:content-type:in-reply-to; s=k1; bh=EhDj Noe3/JC0Wvq34jTb4Txp8C72674LsLZBKo4ri38=; b=TNCFRS9K+hFp4Rdn4i0u ltnPkaWkMoaqydg2WtduSpQ34JwM3o5hAunPza0rJ0+Me/aJc+YUUUTteWx5vBbd xJ/MXF2iC+/sZixjVWv8RYDMNNAv/M9bF1H/w9KGgdPI9cCGt6jEp5h/HXhbLMn4 kuAzNSsaSyurbxWzChy+HzOiG6uPrhsqvhsq2UbLqLqiNlgpxie/aVPduwzN2PJ5 +jMwd8HXrVynOZ3V2fPayIXM6jiTno2QTKRGI9+fDqJn4Q7/Z5ZlP/hSmPxUcllT NMb8ibdtlIDHaEz3yXy5ucxgIRJvcOWi2Lygae3YKRB6MZNzQAJImk56YbPuo3uF 1A== Received: (qmail 188051 invoked from network); 10 Nov 2026 11:24:44 +0100 Received: by mail.zeus03.de with ESMTPSA (TLS_AES_256_GCM_SHA384 encrypted, authenticated); 10 Nov 2026 11:24:44 +0100 X-UD-Smtp-Session: l3s3148p1@tqO2fOlf8JsujnsO Date: Tue, 10 Nov 2026 11:24:44 +0100 From: Wolfram Sang To: Chen-Yu Tsai Cc: Mark Brown , Matthias Brugger , AngeloGioacchino Del Regno , Dmitry Torokhov , Jiri Kosina , Andi Shyti , Benson Leung , Tzung-Bi Shih , linux-mediatek@lists.infradead.org, devicetree@vger.kernel.org, linux-arm-kernel@lists.infradead.org, chrome-platform@lists.linux.dev, linux-input@vger.kernel.org, linux-i2c@vger.kernel.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH v7 6/8] i2c: of-prober: Defer regulator_disable() on successful probe in simple helper Message-ID: References: <20261103043734.2179858-1-wenst@chromium.org> <20261103043734.2179858-7-wenst@chromium.org> X-Mailing-List: linux-i2c@vger.kernel.org List-Id: List-Post: List-Help: List-Subscribe: List-Unsubscribe: List-Owner: Precedence: list MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20261103043734.2179858-7-wenst@chromium.org> On Tue, Nov 03, 2026 at 12:37:30PM +0800, Chen-Yu Tsai wrote: > When a I2C component is found, its device node is immediately enabled. > This triggers device creation and driver binding. The prober will hold > the regulator enable reference across this part. If the driver probes > synchronously, then it happens within this window. On the other hand, > if the driver probes asynchronously, there is a high chance that it > happens after the prober's cleanup function was called, in which case > the regulator would have been disabled when the driver's probe function > is called. This would then require the driver to wait 100 ms for the > hardware to reinitialize, even if the probe function was just a split > second late and the regulator was disabled a few milliseconds ago. > > Recently, some of the drivers for the components that are targeted by the > I2C OF component prober gained the ability to skip waiting for hardware > initialization if the regulator was left enabled. This happens when the > PMIC has them on by default, or if the component prober left them on > after probing the component. > > Tests on the Hana Chromebook showed that if the prober and trackpad > drivers are both builtin, then the time between the prober enabling the > device node and the trackpad driver asynchronously probing is between > 5 ms and 30 ms, though sometimes there are outliers exceeding 100 ms. > > Wait 100 ms before dropping the enable refcount on our end so that the > actual driver has the opportunity to catch and increase the refcount on > their end. > > Signed-off-by: Chen-Yu Tsai Acked-by: Wolfram Sang