From: Arnd Bergmann <arnd@arndb.de>
To: linux-arm-kernel@lists.infradead.org
Cc: Anurup M <anurupvasu@gmail.com>, mark.rutland@arm.com,
        zhangshaokun@hisilicon.com, gabriele.paoloni@huawei.com,
        john.garry@huawei.com, will.deacon@arm.com,
        linux-kernel@vger.kernel.org, xuwei5@hisilicon.com,
        linuxarm@huawei.com, shyju.pv@huawei.com, sanil.kumar@hisilicon.com,
        shiju.jose@huawei.com, Tan Xiaojun <tanxiaojun@huawei.com>,
        anurup.m@huawei.com
Subject: Re: [PATCH v1 03/11] drivers: soc: hisi: Add support for Hisilicon Djtag driver
Date: Wed, 09 Nov 2016 22:40:14 +0100
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On Wednesday, November 9, 2016 9:58:38 AM CET Anurup M wrote:
> 
> > I also see that the compatible strings have the version included in
> > them, and you can probably drop them by requiring them only in the
> > fallback:
> >
> >       compatible = "hisilicon,hip05-cpu-djtag", "hisilicon,djtag-v1";
> >       compatible = "hisilicon,hip05-io-djtag", "hisilicon,djtag-v1";
> >       compatible = "hisilicon,hip06-cpu-djtag", "hisilicon,djtag-v1";
> >       compatible = "hisilicon,hip06-io-djtag", "hisilicon,djtag-v2";
> >       compatible = "hisilicon,hip07-cpu-djtag", "hisilicon,djtag-v2";
> >       compatible = "hisilicon,hip07-io-djtag", "hisilicon,djtag-v2";
> >
> > We want to have the first entry be as specific as possible, but
> > the last (second) entry is the one that can be used by the driver
> > for matching. When a future hip08/hip09/... chip uses an existing
> > interface, you then don't have to update the driver.
> Thanks. I had a similar thought on this. So as I have the version string 
> in the
> second entry "-v(1/2)".
> I can use it in driver for matching. So i think  I will change it as below.
> Please correct me if my understanding is wrong.
> 
>   static const struct of_device_id djtag_of_match[] = {
> -       /* for hip05(D02) cpu die */
> -       { .compatible = "hisilicon,hip05-cpu-djtag-v1",
> +       /* for hisi djtag-v1 cpu die */
> +       { .compatible = "hisilicon,hisi-cpu-djtag-v1",
>                  .data = djtag_readwrite_v1 },
> -       /* for hip05(D02) io die */
> -       { .compatible = "hisilicon,hip05-io-djtag-v1",
> +       /* for hisi djtag-v1 io die */
> +       { .compatible = "hisilicon,hisi-io-djtag-v1",

>From the code it looks like "hisilicon,hisi-io-djtag-v1" and
"hisilicon,hisi-cpu-djtag-v1" have the same register-level interface,
so we just need one compatible string for them to match the driver.

	Arnd