From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from relay3-d.mail.gandi.net (relay3-d.mail.gandi.net [217.70.183.195]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id AEB3F188903; Tue, 3 Sep 2024 16:01:27 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=217.70.183.195 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1725379290; cv=none; b=Yn5Yq+NwPeIZRy1Bw3T0gasA3VH+1LsXF7qSjJU4eCnRmLq4CRD7+SYar2NBDb2VVTUQVW6b9HUI2ZZnDAMGWKPi2Nsy1tYH7Hv3PwfagPE7gJI6dUdy2Ejny0izUBd9IWgTaV4w8raR7SV6C67V/4Nd5ABhuRc/85Iy51NnVz0= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1725379290; c=relaxed/simple; bh=JHkZaHTyZr8FrXiNtLB8ONHDQXBeymJgLt3plAsYQ9U=; h=Date:From:To:Cc:Subject:Message-ID:In-Reply-To:References: MIME-Version:Content-Type; b=GcFl7jV40vwN7D2LHgHnufBSk8/V3u3WVHBSeENDWPGWPIq8ul+4EYB6q97otQDgjAPGVhWoV2UA2LDWfsT4dE9VcgBEFuout2utDhn463YVO45AyAIoON4KDNf0UKv2BL2W5jhGPGo2AS4xUoH5IsyqOpgGSxRzNY4usmdjRyA= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=reject dis=none) header.from=bootlin.com; spf=pass smtp.mailfrom=bootlin.com; dkim=pass (2048-bit key) header.d=bootlin.com header.i=@bootlin.com header.b=c+Fmen+1; arc=none smtp.client-ip=217.70.183.195 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=reject dis=none) header.from=bootlin.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=bootlin.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=bootlin.com header.i=@bootlin.com header.b="c+Fmen+1" Received: by mail.gandi.net (Postfix) with ESMTPSA id 1695160003; Tue, 3 Sep 2024 16:01:17 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=bootlin.com; s=gm1; t=1725379280; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=TOEHRL0jTkqVJGqC1aF4rVCGmks2TS1OH/JK8xFsn/A=; b=c+Fmen+107aZTxRPesX1RF0jOVv9G1jUVeZALqhujtGQggZXA7w9Up9m2Q8ybdjodWqpK/ WM+uKhy6OpKV6HrweUA8FA5wjh1QA4ljeH5VoAYJufX0f/z2nnBTXwYrToXqs1C6F+bImD 5sTuQ+ub2E9GLdELHmZb3HsAWADILFlGNR7iAqLPdUT8Op+8sURREaOQMQUB+pVoRnomcC 9AFaVAkqVi6FG/bVN/dETRKnJQslq7jw3IMydXJa50GsULYLzKRSh2TZ+KTyDH+JPYbZ+X O8MRC1YafAcQsnU92sLa/Cw2YKVTqNXq6U/J/ePSLIaPIRFXW8NdkjdTCbAoFg== Date: Tue, 3 Sep 2024 18:01:16 +0200 From: Herve Codina To: Lee Jones Cc: Geert Uytterhoeven , Andy Shevchenko , Simon Horman , Arnd Bergmann , Derek Kiernan , Dragan Cvetic , Greg Kroah-Hartman , Bjorn Helgaas , Philipp Zabel , Lars Povlsen , Steen Hegelund , Daniel Machon , UNGLinuxDriver@microchip.com, Rob Herring , Saravana Kannan , "David S. Miller" , Eric Dumazet , Jakub Kicinski , Paolo Abeni , Horatiu Vultur , Andrew Lunn , linux-kernel@vger.kernel.org, netdev@vger.kernel.org, linux-pci@vger.kernel.org, linux-arm-kernel@lists.infradead.org, devicetree@vger.kernel.org, Allan Nielsen , Luca Ceresoli , Thomas Petazzoni , =?UTF-8?B?Q2zDqW1lbnQgTMOpZ2Vy?= Subject: Re: [PATCH v5 3/8] mfd: syscon: Add reference counting and device managed support Message-ID: <20240903180116.717a499b@bootlin.com> In-Reply-To: <20240903153839.GB6858@google.com> References: <20240808154658.247873-1-herve.codina@bootlin.com> <20240808154658.247873-4-herve.codina@bootlin.com> <20240903153839.GB6858@google.com> Organization: Bootlin X-Mailer: Claws Mail 4.3.0 (GTK 3.24.43; x86_64-redhat-linux-gnu) Precedence: bulk X-Mailing-List: linux-pci@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit X-GND-Sasl: herve.codina@bootlin.com Hi Lee, On Tue, 3 Sep 2024 16:38:39 +0100 Lee Jones wrote: > On Thu, 08 Aug 2024, Herve Codina wrote: > > > From: Clément Léger > > > > Syscon releasing is not supported. > > Without release function, unbinding a driver that uses syscon whether > > explicitly or due to a module removal left the used syscon in a in-use > > state. > > > > For instance a syscon_node_to_regmap() call from a consumer retrieves a > > syscon regmap instance. Internally, syscon_node_to_regmap() can create > > syscon instance and add it to the existing syscon list. No API is > > available to release this syscon instance, remove it from the list and > > free it when it is not used anymore. > > > > Introduce reference counting in syscon in order to keep track of syscon > > usage using syscon_{get,put}() and add a device managed version of > > syscon_regmap_lookup_by_phandle(), to automatically release the syscon > > instance on the consumer removal. > > > > Signed-off-by: Clément Léger > > Signed-off-by: Herve Codina > > --- > > drivers/mfd/syscon.c | 138 ++++++++++++++++++++++++++++++++++--- > > include/linux/mfd/syscon.h | 16 +++++ > > 2 files changed, 144 insertions(+), 10 deletions(-) > > This doesn't look very popular. > > What are the potential ramifications for existing users? > Existing user don't use devm_syscon_regmap_lookup_by_phandle() nor syscon_put_regmap(). So refcount is incremented but never decremented. syscon is never released. Exactly the same as current implementation. Nothing change for existing users. Best regards, Hervé