From: Thomas Petazzoni <thomas.petazzoni@free-electrons.com>
To: Jisheng Zhang <Jisheng.Zhang@synaptics.com>
Cc: "Gregory CLEMENT" <gregory.clement@free-electrons.com>,
"Ulf Hansson" <ulf.hansson@linaro.org>,
"Adrian Hunter" <adrian.hunter@intel.com>,
linux-mmc@vger.kernel.org, "Rob Herring" <robh+dt@kernel.org>,
devicetree@vger.kernel.org, "Jason Cooper" <jason@lakedaemon.net>,
"Andrew Lunn" <andrew@lunn.ch>,
"Sebastian Hesselbarth" <sebastian.hesselbarth@gmail.com>,
linux-arm-kernel@lists.infradead.org,
"Antoine Tenart" <antoine.tenart@free-electrons.com>,
"Miquèl Raynal" <miquel.raynal@free-electrons.com>,
"Nadav Haklai" <nadavh@marvell.com>,
"Shadi Ammouri" <shadi@marvell.com>,
"Yehuda Yitschak" <yehuday@marvell.com>,
"Omri Itach" <omrii@marvell.com>,
"Hanna Hawa" <hannah@marvell.com>,
"Igal Liberman" <igall@marvell.com>, "Marcin Wojtas" <mw@s>
Subject: Re: [PATCH v2] mmc: sdhci-xenon: Fix clock resource by adding an optional bus clock
Date: Sat, 30 Sep 2017 08:07:10 +0200 [thread overview]
Message-ID: <20170930080710.119c0258@windsurf> (raw)
In-Reply-To: <20170930104109.60853202@xhacker.debian>
Hello,
On Sat, 30 Sep 2017 10:41:09 +0800, Jisheng Zhang wrote:
> > + priv->axi_clk = devm_clk_get(&pdev->dev, "axi");
> > + if (IS_ERR(priv->axi_clk)) {
> > + err = PTR_ERR(priv->axi_clk);
> > + if (err == -EPROBE_DEFER)
> > + goto err_clk;
> > + priv->axi_clk = NULL;
>
> IMHO, this assignment could be removed. What do you think?
No, because if the clock is not present in the Device Tree,
priv->axi_clk will contain an error code encoded as a pointer, so
priv->axi_clk will not be NULL. Hence the rest of the code that will
operate on this clock will believe there is a valid clock pointed by
priv->axi_clk. So we really want to reset it to NULL when there was an
error getting the clock.
Best regards,
Thomas
--
Thomas Petazzoni, CTO, Free Electrons
Embedded Linux and Kernel engineering
http://free-electrons.com
WARNING: multiple messages have this Message-ID (diff)
From: thomas.petazzoni@free-electrons.com (Thomas Petazzoni)
To: linux-arm-kernel@lists.infradead.org
Subject: [PATCH v2] mmc: sdhci-xenon: Fix clock resource by adding an optional bus clock
Date: Sat, 30 Sep 2017 08:07:10 +0200 [thread overview]
Message-ID: <20170930080710.119c0258@windsurf> (raw)
In-Reply-To: <20170930104109.60853202@xhacker.debian>
Hello,
On Sat, 30 Sep 2017 10:41:09 +0800, Jisheng Zhang wrote:
> > + priv->axi_clk = devm_clk_get(&pdev->dev, "axi");
> > + if (IS_ERR(priv->axi_clk)) {
> > + err = PTR_ERR(priv->axi_clk);
> > + if (err == -EPROBE_DEFER)
> > + goto err_clk;
> > + priv->axi_clk = NULL;
>
> IMHO, this assignment could be removed. What do you think?
No, because if the clock is not present in the Device Tree,
priv->axi_clk will contain an error code encoded as a pointer, so
priv->axi_clk will not be NULL. Hence the rest of the code that will
operate on this clock will believe there is a valid clock pointed by
priv->axi_clk. So we really want to reset it to NULL when there was an
error getting the clock.
Best regards,
Thomas
--
Thomas Petazzoni, CTO, Free Electrons
Embedded Linux and Kernel engineering
http://free-electrons.com
WARNING: multiple messages have this Message-ID (diff)
From: Thomas Petazzoni <thomas.petazzoni@free-electrons.com>
To: Jisheng Zhang <Jisheng.Zhang@synaptics.com>
Cc: "Gregory CLEMENT" <gregory.clement@free-electrons.com>,
"Ulf Hansson" <ulf.hansson@linaro.org>,
"Adrian Hunter" <adrian.hunter@intel.com>,
linux-mmc@vger.kernel.org, "Rob Herring" <robh+dt@kernel.org>,
devicetree@vger.kernel.org, "Jason Cooper" <jason@lakedaemon.net>,
"Andrew Lunn" <andrew@lunn.ch>,
"Sebastian Hesselbarth" <sebastian.hesselbarth@gmail.com>,
linux-arm-kernel@lists.infradead.org,
"Antoine Tenart" <antoine.tenart@free-electrons.com>,
"Miquèl Raynal" <miquel.raynal@free-electrons.com>,
"Nadav Haklai" <nadavh@marvell.com>,
"Shadi Ammouri" <shadi@marvell.com>,
"Yehuda Yitschak" <yehuday@marvell.com>,
"Omri Itach" <omrii@marvell.com>,
"Hanna Hawa" <hannah@marvell.com>,
"Igal Liberman" <igall@marvell.com>,
"Marcin Wojtas" <mw@semihalf.com>,
Stable <stable@vger.kernel.org>
Subject: Re: [PATCH v2] mmc: sdhci-xenon: Fix clock resource by adding an optional bus clock
Date: Sat, 30 Sep 2017 08:07:10 +0200 [thread overview]
Message-ID: <20170930080710.119c0258@windsurf> (raw)
In-Reply-To: <20170930104109.60853202@xhacker.debian>
Hello,
On Sat, 30 Sep 2017 10:41:09 +0800, Jisheng Zhang wrote:
> > + priv->axi_clk = devm_clk_get(&pdev->dev, "axi");
> > + if (IS_ERR(priv->axi_clk)) {
> > + err = PTR_ERR(priv->axi_clk);
> > + if (err == -EPROBE_DEFER)
> > + goto err_clk;
> > + priv->axi_clk = NULL;
>
> IMHO, this assignment could be removed. What do you think?
No, because if the clock is not present in the Device Tree,
priv->axi_clk will contain an error code encoded as a pointer, so
priv->axi_clk will not be NULL. Hence the rest of the code that will
operate on this clock will believe there is a valid clock pointed by
priv->axi_clk. So we really want to reset it to NULL when there was an
error getting the clock.
Best regards,
Thomas
--
Thomas Petazzoni, CTO, Free Electrons
Embedded Linux and Kernel engineering
http://free-electrons.com
next prev parent reply other threads:[~2017-09-30 6:07 UTC|newest]
Thread overview: 21+ messages / expand[flat|nested] mbox.gz Atom feed top
2017-09-29 13:04 [PATCH v2] mmc: sdhci-xenon: Fix clock resource by adding an optional bus clock Gregory CLEMENT
2017-09-29 13:04 ` Gregory CLEMENT
2017-09-29 13:04 ` Gregory CLEMENT
[not found] ` <20170929130435.6805-1-gregory.clement-wi1+55ScJUtKEb57/3fJTNBPR1lH4CV8@public.gmane.org>
2017-09-29 18:42 ` zhoujie wu
2017-09-29 18:42 ` zhoujie wu
2017-09-29 18:42 ` zhoujie wu
2017-09-30 2:32 ` Jisheng Zhang
2017-09-30 2:32 ` Jisheng Zhang
2017-09-30 2:32 ` Jisheng Zhang
2017-09-30 2:41 ` Jisheng Zhang
2017-09-30 2:41 ` Jisheng Zhang
2017-09-30 2:41 ` Jisheng Zhang
2017-09-30 6:07 ` Thomas Petazzoni [this message]
2017-09-30 6:07 ` Thomas Petazzoni
2017-09-30 6:07 ` Thomas Petazzoni
2017-09-30 6:17 ` Jisheng Zhang
2017-09-30 6:17 ` Jisheng Zhang
2017-09-30 6:17 ` Jisheng Zhang
2017-10-02 14:32 ` Gregory CLEMENT
2017-10-02 14:32 ` Gregory CLEMENT
2017-10-02 14:32 ` Gregory CLEMENT
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