Re: [PATCH v9 0/3] Tango PCIe controller support

From: Mason <slash.tmp@free.fr>
To: Bjorn Helgaas <helgaas@kernel.org>
Cc: Marc Gonzalez <marc_gonzalez@sigmadesigns.com>,
	Marc Zyngier <marc.zyngier@arm.com>,
	Thomas Gleixner <tglx@linutronix.de>,
	linux-pci <linux-pci@vger.kernel.org>,
	Linux ARM <linux-arm-kernel@lists.infradead.org>,
	LKML <linux-kernel@vger.kernel.org>,
	DT <devicetree@vger.kernel.org>,
	Thibaud Cornic <thibaud_cornic@sigmadesigns.com>
Subject: Re: [PATCH v9 0/3] Tango PCIe controller support
Date: Wed, 5 Jul 2017 22:39:19 +0200	[thread overview]
Message-ID: <5a1207cb-31fd-6b85-86af-8c37bd57ad4f@free.fr> (raw)
In-Reply-To: <20170705180359.GL13824@bhelgaas-glaptop.roam.corp.google.com>

On 05/07/2017 20:03, Bjorn Helgaas wrote:

> On Wed, Jul 05, 2017 at 12:55:37AM +0200, Mason wrote:
>
>> On 04/07/2017 22:24, Bjorn Helgaas wrote:
>>
>>> I made the trivial changes I mentioned, added a dependency on
>>> CONFIG_BROKEN (for the config/MMIO muxing issue), and put these on
>>> pci/host-tango.  I can't build or test this, so I probably broke
>>> something in the process.  I think the combination of the boot-time
>>> warning, the taint, and CONFIG_BROKEN is a reasonable amount of
>>> warning that a user should expect issues.
>>>
>>> Can you take a look and see if it works for you?
>>>
>>> https://git.kernel.org/pub/scm/linux/kernel/git/helgaas/pci.git/log/?h=pci/host-tango
>>
>> Thanks. I'll take it for a spin ASAP.
>>
>> TAINT_CRAP... Smirk. I didn't see that one in the docs:
>> https://www.kernel.org/doc/html/latest/admin-guide/tainted-kernels.html
>>
>> Oh wait... TAINT_CRAP is "C" => a staging driver has been loaded
> 
> I wish it had a less pejorative, more descriptive name.  But it seems like
> the closest to this situation.

Maybe it is not too late to submit a patch to Linus
renaming TAINT_CRAP?

Here are a few candidates, off the top of my head:

TAINT_STAGING
TAINT_STAGING_DRIVER
TAINT_BROKEN_HW
TAINT_BROKEN_HARDWARE
TAINT_USE_AT_YOUR_OWN_RISK

>> The one issue I anticipate with "depends on BROKEN" is
>> when I add support for revision 2, which isn't broken.
> 
> How about this:
> 
>   - Rename PCIE_TANGO to PCIE_TANGO_REV1
>   - PCIE_TANGO_REV1 depends on BROKEN
>   - Add rev2 support later, enabled by PCIE_TANGO
>   - PCIE_TANGO_REV1 depends on PCIE_TANGO && BROKEN
> 
> I updated pci/host-tango along these lines (without rev2 support,
> obviously).

And support for REV1 wouldn't be compiled in, unless
BROKEN is selected? Yes, I think that could fly.

Don't you think the naming should follow the DT
convention of using the first SoC embedding the
IP (for the compatible string) ?

PCIE_TANGO_REV1 vs PCIE_TANGO_SMP8759

> I forgot to ask for a MAINTAINERS update.  Can you send that, too,
> please?

There's a "catch-all" rule for everything tango-related:

ARM/TANGO ARCHITECTURE
M:	Marc Gonzalez <marc_gonzalez@sigmadesigns.com>
L:	linux-arm-kernel@lists.infradead.org
S:	Maintained
N:	tango

Is that enough?

> Which reminds me -- are these two addreses
> 
>   Marc Gonzalez <marc_gonzalez@sigmadesigns.com>
>   Mason <slash.tmp@free.fr>
> 
> different names for the same person?  Conversations are easier for me
> if I can keep who's who straight :)

Well, there are many voices inside my head, but yes,
respectively professional and personal addresses.

Regards.