Re: [PATCH 07/15] cxl/acpi: Check RCH's PCIe Host Bridge ACPI ID

From: Jonathan Cameron <Jonathan.Cameron@huawei.com>
To: Robert Richter <rrichter@amd.com>
Cc: Alison Schofield <alison.schofield@intel.com>,
	Vishal Verma <vishal.l.verma@intel.com>,
	Ira Weiny <ira.weiny@intel.com>,
	Ben Widawsky <bwidawsk@kernel.org>,
	Dan Williams <dan.j.williams@intel.com>,
	<linux-cxl@vger.kernel.org>, <linux-kernel@vger.kernel.org>,
	Bjorn Helgaas <bhelgaas@google.com>,
	"Rafael J. Wysocki" <rafael@kernel.org>,
	Len Brown <lenb@kernel.org>
Subject: Re: [PATCH 07/15] cxl/acpi: Check RCH's PCIe Host Bridge ACPI ID
Date: Thu, 1 Sep 2022 11:14:03 +0100	[thread overview]
Message-ID: <20220901111403.00003bff@huawei.com> (raw)
In-Reply-To: <YxBOVH+irgYSbEIz@rric.localdomain>

On Thu, 1 Sep 2022 08:16:52 +0200
Robert Richter <rrichter@amd.com> wrote:

> On 31.08.22 11:20:28, Jonathan Cameron wrote:
> > Robert Richter <rrichter@amd.com> wrote:  
> 
> > > +static const struct acpi_device_id cxl_host_ids[] = {
> > > +	{ "ACPI0016", 0 },
> > > +	{ "PNP0A08", 0 },
> > > +	{ },  
> > 
> > Trivial but no comma after a null terminator.   Always good to make
> > it harder for people to add things where they really shouldn't!  
> 
> Can do this.
> 
> > pci_root.c avoids using an acpi_device_id table for similar matching.
> > I think the point being to separate probe type use of this table
> > from cases where we aren't using a normal device probe.
> > So to remain consistent with that, I would just grab the hid
> > and match it directly in this code.  
> 
> Grabbing the hid only is actually a violation of the acpi spec as a
> cid could be used interchangeable. It must also work then.
> 
> It is also not possible to use something like probe or a handler
> matching the ids because the hosts must be enabled with the already
> existing drivers and handlers. Suppose there are multiple handlers for
> the same ids, the first handler wins and all other never get called.
> 
> To me it looks sane and simple to use acpi_match_device_ids() here.

Ok. One for the ACPI maintainers to comment on if they wish - I'm fine with this

Reviewed-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>

> 
> -Robert
> 
> > 
> > I don't feel that strongly about this if the ACPI maintainers are
> > fine with reusing this infrastructure as you have it here.  