linux-kernel - Re: [PATCH v7 24/30] net: wan: Add framer framework support

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Date:   Fri, 6 Oct 2023 15:08:10 -0700
From:   Jakub Kicinski <kuba@...nel.org>
To:     Herve Codina <herve.codina@...tlin.com>
Cc:     "David S. Miller" <davem@...emloft.net>,
        Eric Dumazet <edumazet@...gle.com>,
        Paolo Abeni <pabeni@...hat.com>, Andrew Lunn <andrew@...n.ch>,
        Rob Herring <robh+dt@...nel.org>,
        Krzysztof Kozlowski <krzysztof.kozlowski+dt@...aro.org>,
        Conor Dooley <conor+dt@...nel.org>,
        Linus Walleij <linus.walleij@...aro.org>,
        Qiang Zhao <qiang.zhao@....com>, Li Yang <leoyang.li@....com>,
        Liam Girdwood <lgirdwood@...il.com>,
        Mark Brown <broonie@...nel.org>,
        Jaroslav Kysela <perex@...ex.cz>,
        Takashi Iwai <tiwai@...e.com>,
        Shengjiu Wang <shengjiu.wang@...il.com>,
        Xiubo Li <Xiubo.Lee@...il.com>,
        Fabio Estevam <festevam@...il.com>,
        Nicolin Chen <nicoleotsuka@...il.com>,
        Christophe Leroy <christophe.leroy@...roup.eu>,
        Randy Dunlap <rdunlap@...radead.org>, netdev@...r.kernel.org,
        linuxppc-dev@...ts.ozlabs.org, devicetree@...r.kernel.org,
        linux-kernel@...r.kernel.org, linux-gpio@...r.kernel.org,
        linux-arm-kernel@...ts.infradead.org, alsa-devel@...a-project.org,
        Simon Horman <horms@...nel.org>,
        Christophe JAILLET <christophe.jaillet@...adoo.fr>,
        Thomas Petazzoni <thomas.petazzoni@...tlin.com>
Subject: Re: [PATCH v7 24/30] net: wan: Add framer framework support

On Thu, 28 Sep 2023 09:06:42 +0200 Herve Codina wrote:
> +menu "Framer Subsystem"
> +
> +config GENERIC_FRAMER
> +	bool "Framer Core"
> +	help
> +	  Generic Framer support.
> +	  A framer is a component in charge of an E1/T1 line interface.
> +	  Connected usually to a TDM bus, it converts TDM frames to/from E1/T1
> +	  frames. It also provides information related to the E1/T1 line.
> +	  Used with HDLC, the network can be reached through the E1/T1 line.
> +
> +	  This framework is designed to provide a generic interface for framer
> +	  devices present in the kernel. This layer will have the generic
> +	  API by which framer drivers can create framer using the framer
> +	  framework and framer users can obtain reference to the framer.
> +	  All the users of this framework should select this config.

maybe make the menu a menuconfig with info about framers but hide 
the GENERIC_FRAMER symbol? The driver 'select' it anyway, what's
the point of prompting the user..

> +	if (WARN_ON(!dev))
> +		return ERR_PTR(-EINVAL);

no defensive programming, let the kernel crash

> +	ret = framer_pm_runtime_get_sync(framer);
> +	if (ret < 0 && ret != -EOPNOTSUPP)
> +		goto err_pm_sync;
> +
> +	ret = 0; /* Override possible ret == -EOPNOTSUPP */

This looks pointless given that ret is either overwritten or not used
later on

> +	mutex_lock(&framer->mutex);
> +	if (framer->power_count == 0 && framer->ops->power_on) {
> +		ret = framer->ops->power_on(framer);
> +		if (ret < 0) {
> +			dev_err(&framer->dev, "framer poweron failed --> %d\n", ret);
> +			goto err_pwr_on;
> +		}
> +	}
> +	++framer->power_count;
> +	mutex_unlock(&framer->mutex);
> +	return 0;