From: Marc Zyngier <marc.zyngier@arm.com>
To: Linus Walleij <linus.walleij@linaro.org>,
Bintian Wang <bintian.wang@huawei.com>,
Russell King - ARM Linux <linux@arm.linux.org.uk>
Cc: "linux-arm-kernel@lists.infradead.org"
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Subject: Re: [PATCH v9 4/6] Documentation: DT: PL011: hi6220: add compatible string for Hisilicon designed UART
Date: Tue, 02 Jun 2015 10:13:26 +0100 [thread overview]
Message-ID: <556D73B6.4090608@arm.com> (raw)
In-Reply-To: <CACRpkdav_5x6RC9F++ErvqGyxDCF-=kap7-jCsO4zZ6QGVLfBQ@mail.gmail.com>
On 02/06/15 09:59, Linus Walleij wrote:
> On Sat, May 30, 2015 at 3:50 AM, Bintian Wang <bintian.wang@huawei.com> wrote:
>
>> Hisilicon does some performance enhancements based on PL011(e.g. larger
>> FIFO length), so add one compatible string "hisilicon,hi6220-uart" for
>
> That compatible string in the commit message is not even
> the same as in the patch.
>
>> future optimisations or workarounds works.
>>
>> Signed-off-by: Bintian Wang <bintian.wang@huawei.com>
>> Suggested-by: Mark Rutland <mark.rutland@arm.com>
>
> Maybe I missed out on the earlier conversation, but do you
> mean that the PrimeCell ID has not been properly set up
> to something unique in this HiSilicon version of the PL011
> block?
>
> Even if so: do not override the compatible string like this,
> that is not the PrimeCell style.
>
> Define an 8 bit vendor ID (like tha ASCII for 'H' 0x48
> or whatever) and encode it for these variants, if the
> hardware is just using the ARM default PrimeCell
> ID, override it in the device tree like Broadcom
> are doing in arch/arm/boot/dts/bcm2835.dtsi:
>
> arm,primecell-periphid = <0x00241011>;
>
> Maybe yours would be:
>
> arm,primecell-periphid = <0x00048011>;
>
> For a first HiSilicon variant, then do some
> <include/linux/amba/bus.h>:
>
> enum amba_vendor {
> AMBA_VENDOR_ARM = 0x41,
> + AMBA_VENDOR_HISILICON = 0x48,
>
> Then patch drivers/tty/serial/amba_pl011.c to add vendor_hisilicon
> and a match table for 0x00048011 just like everyone else.
That feels weird. This amba_vendor enum is not under control of the DT
author, nor the kernel. This is a set of codes that are managed by a
third party (probably ARM). What if some company with a name starting
with 'H' (Hilarious Inc?) comes up with some actual HW and ends up
conflicting with the above?
Thanks,
M.
--
Jazz is not dead. It just smells funny...
next prev parent reply other threads:[~2015-06-02 9:13 UTC|newest]
Thread overview: 21+ messages / expand[flat|nested] mbox.gz Atom feed top
2015-05-30 1:50 [PATCH v9 0/6] arm64,hi6220: Enable Hisilicon Hi6220 SoC Bintian Wang
2015-05-30 1:50 ` [PATCH v9 1/6] arm64: Enable Hisilicon ARMv8 SoC family in Kconfig and defconfig Bintian Wang
2015-05-30 1:50 ` [PATCH v9 2/6] arm64: hi6220: Document devicetree bindings for Hisilicon hi6220 SoC Bintian Wang
2015-06-04 4:36 ` Rob Herring
2015-06-04 7:23 ` Bintian
2015-05-30 1:50 ` [PATCH v9 3/6] clk: hi6220: Document devicetree bindings for hi6220 clock Bintian Wang
2015-05-30 1:50 ` [PATCH v9 4/6] Documentation: DT: PL011: hi6220: add compatible string for Hisilicon designed UART Bintian Wang
2015-06-02 8:59 ` Linus Walleij
2015-06-02 9:13 ` Marc Zyngier [this message]
2015-06-02 9:43 ` Russell King - ARM Linux
2015-06-02 10:55 ` Bintian
2015-06-02 11:24 ` Russell King - ARM Linux
2015-06-02 11:46 ` Bintian
2015-05-30 1:51 ` [PATCH v9 5/6] arm64: dts: Add dts files for Hisilicon Hi6220 SoC Bintian Wang
2015-06-03 3:10 ` Bintian
2015-06-09 0:55 ` Shawn Guo
2015-06-09 1:39 ` Bintian
2015-06-09 2:30 ` Bintian
2015-05-30 1:51 ` [PATCH v9 6/6] dt-bindings: Add header file of hi6220 clock driver Bintian Wang
2015-06-02 0:14 ` [PATCH v9 0/6] arm64,hi6220: Enable Hisilicon Hi6220 SoC Kevin Hilman
2015-06-02 3:57 ` Bintian
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