From: "Y.B. Lu" <yangbo.lu@nxp.com>
To: Arnd Bergmann <arnd@arndb.de>, Ulf Hansson <ulf.hansson@linaro.org>
Cc: linux-mmc <linux-mmc@vger.kernel.org>,
Scott Wood <oss@buserror.net>,
"linuxppc-dev@lists.ozlabs.org" <linuxppc-dev@lists.ozlabs.org>,
"devicetree@vger.kernel.org" <devicetree@vger.kernel.org>,
"linux-arm-kernel@lists.infradead.org"
<linux-arm-kernel@lists.infradead.org>,
"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
linux-clk <linux-clk@vger.kernel.org>,
"linux-i2c@vger.kernel.org" <linux-i2c@vger.kernel.org>,
"iommu@lists.linux-foundation.org"
<iommu@lists.linux-foundation.org>,
"netdev@vger.kernel.org" <netdev@vger.kernel.org>,
Mark Rutland <mark.rutland@arm.com>,
Rob Herring <robh+dt@kernel.org>,
Russell King <linux@arm.linux.org.uk>,
Jochen Friedrich <jochen@scram.de>,
Joerg Roedel <joro@8bytes.org>,
Claudiu Manoil <claudiu.manoil@freescale.com>,
"Bhupesh Sharma" <bhupesh.sharma@freescale.com>,
Qiang Zhao <qiang.zhao@nxp.com>,
"Kumar Gala" <galak@codeaurora.org>,
Santosh Shilimkar <ssantosh@kernel.org>,
Leo Li <leoyang.li@nxp.com>, "X.B. Xie" <xiaobo.xie@nxp.com>
Subject: RE: [v11, 7/8] base: soc: introduce soc_device_match() interface
Date: Wed, 7 Sep 2016 04:10:32 +0000 [thread overview]
Message-ID: <HE1PR04MB088939A28A68035F3393A441F8F80@HE1PR04MB0889.eurprd04.prod.outlook.com> (raw)
In-Reply-To: <6515108.aCEls7dUuW@wuerfel>
Hi Anrd and Uffe,
Thank you for your comment.
Please see my comment inline.
Best regards,
Yangbo Lu
> -----Original Message-----
> From: Arnd Bergmann [mailto:arnd@arndb.de]
> Sent: Tuesday, September 06, 2016 8:46 PM
> To: Ulf Hansson
> Cc: Y.B. Lu; linux-mmc; Scott Wood; linuxppc-dev@lists.ozlabs.org;
> devicetree@vger.kernel.org; linux-arm-kernel@lists.infradead.org; linux-
> kernel@vger.kernel.org; linux-clk; linux-i2c@vger.kernel.org;
> iommu@lists.linux-foundation.org; netdev@vger.kernel.org; Mark Rutland;
> Rob Herring; Russell King; Jochen Friedrich; Joerg Roedel; Claudiu Manoil;
> Bhupesh Sharma; Qiang Zhao; Kumar Gala; Santosh Shilimkar; Leo Li; X.B.
> Xie
> Subject: Re: [v11, 7/8] base: soc: introduce soc_device_match() interface
>
> On Tuesday, September 6, 2016 1:44:23 PM CEST Ulf Hansson wrote:
> > On 6 September 2016 at 10:28, Yangbo Lu <yangbo.lu@nxp.com> wrote:
> > > We keep running into cases where device drivers want to know the
> > > exact version of the a SoC they are currently running on. In the
> > > past, this has usually been done through a vendor specific API that
> > > can be called by a driver, or by directly accessing some kind of
> > > version register that is not part of the device itself but that
> > > belongs to a global register area of the chip.
>
> Please add "From: Arnd Bergmann <arnd@arndb.de>" as the first line, to
> preserve authorship. If you use "git send-email" or "git format-patch",
> that should happen automatically if the author field is set right (if not,
> use 'git commit --amend --author="Arnd Bergmann <arnd@arndb.de>"'
> to fix it).
>
[Lu Yangbo-B47093] Oh, I'm sorry for my careless. Will correct it in next version.
> > > +
> > > +/*
> > > + * soc_device_match - identify the SoC in the machine
> > > + * @matches: zero-terminated array of possible matches
> >
> > Perhaps also express the constraint on the matching entries. As you
> > need at least one of the ->machine(), ->family(), ->revision() or
> > ->soc_id() callbacks implemented, right!?
>
> They are not callbacks, just strings. Having an empty entry indicates the
> end of the array, and this is not called.
>
> > > + *
> > > + * returns the first matching entry of the argument array, or NULL
> > > + * if none of them match.
> > > + *
> > > + * This function is meant as a helper in place of of_match_node()
> > > + * in cases where either no device tree is available or the
> > > + information
> > > + * in a device node is insufficient to identify a particular
> > > + variant
> > > + * by its compatible strings or other properties. For new devices,
> > > + * the DT binding should always provide unique compatible strings
> > > + * that allow the use of of_match_node() instead.
> > > + *
> > > + * The calling function can use the .data entry of the
> > > + * soc_device_attribute to pass a structure or function pointer for
> > > + * each entry.
> >
> > I don't get the use case behind this, could you elaborate?
> >
> > Perhaps we should postpone adding the .data entry until we actually
> > see a need for it?
>
> I think the interface is rather useless without a way to figure out which
> entry you got. Almost all users of of_match_node() actually use the
> returned ->data field, and I expect this to be the same here.
>
> > > + */
> > > +const struct soc_device_attribute *soc_device_match(
> > > + const struct soc_device_attribute *matches) {
> > > + struct device *dev;
> > > + int ret;
> > > +
> > > + for (ret = 0; ret == 0; matches++) {
> >
> > This loop looks a bit weird and unsafe.
>
> Ah, and I thought I was being clever ;-)
>
> > 1) Perhaps using a while loop makes this more readable?
> > 2) As this is an exported API, I guess validation of the ->matches
> > pointer needs to be done before accessing it.
>
> Sounds fine.
[Lu Yangbo-B47093] Ok, Will change this according to Uffe.
And actually there is issue with this for() when I verified it again this morning.
We will get matches++ rather than matches which is correct finally :)
>
> > > + if (!(matches->machine || matches->family ||
> > > + matches->revision || matches->soc_id))
> > > + return NULL;
> > > + dev = NULL;
> >
> > There's no need to use a struct device just to assign it to NULL.
> > Instead just provide the function below with NULL.
> >
> > > + ret = bus_for_each_dev(&soc_bus_type, dev, (void
> *)matches,
> > > + soc_device_match_one);
>
>
> I don't remember what led to this, I think you are right, we should just
> pass NULL as most other callers.
[Lu Yangbo-B47093] Will correct it. Thanks. :)
>
> Thanks for the review.
>
> ARnd
next prev parent reply other threads:[~2016-09-07 4:10 UTC|newest]
Thread overview: 17+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-09-06 8:28 [v11, 0/8] Fix eSDHC host version register bug Yangbo Lu
2016-09-06 8:28 ` [v11, 1/8] dt: bindings: update Freescale DCFG compatible Yangbo Lu
2016-09-06 8:28 ` [v11, 2/8] ARM64: dts: ls2080a: add device configuration node Yangbo Lu
2016-09-06 8:28 ` [v11, 3/8] dt: bindings: move guts devicetree doc out of powerpc directory Yangbo Lu
2016-09-06 8:28 ` [v11, 4/8] powerpc/fsl: move mpc85xx.h to include/linux/fsl Yangbo Lu
2016-09-06 8:28 ` [v11, 5/8] soc: fsl: add GUTS driver for QorIQ platforms Yangbo Lu
2016-09-09 3:47 ` Scott Wood
2016-09-12 6:39 ` Y.B. Lu
2016-09-12 23:25 ` Scott Wood
2016-09-13 7:23 ` Y.B. Lu
2016-09-13 22:24 ` Scott Wood
2016-09-06 8:28 ` [v11, 6/8] MAINTAINERS: add entry for Freescale SoC drivers Yangbo Lu
2016-09-06 8:28 ` [v11, 7/8] base: soc: introduce soc_device_match() interface Yangbo Lu
2016-09-06 11:44 ` Ulf Hansson
2016-09-06 12:46 ` Arnd Bergmann
2016-09-07 4:10 ` Y.B. Lu [this message]
2016-09-06 8:28 ` [v11, 8/8] mmc: sdhci-of-esdhc: fix host version for T4240-R1.0-R2.0 Yangbo Lu
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