linux-kernel - Re: [PATCH 3/3] PCI: Set pref for mem64 resource of pcie device

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Date:	Wed, 8 Apr 2015 21:11:21 -0700
From:	Yinghai Lu <yinghai@...nel.org>
To:	Benjamin Herrenschmidt <benh@...nel.crashing.org>
Cc:	Bjorn Helgaas <bhelgaas@...gle.com>,
	David Miller <davem@...emloft.net>,
	David Ahern <david.ahern@...cle.com>,
	"linux-pci@...r.kernel.org" <linux-pci@...r.kernel.org>,
	"sparclinux@...r.kernel.org" <sparclinux@...r.kernel.org>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
	"stable@...r.kernel.org" <stable@...r.kernel.org>
Subject: Re: [PATCH 3/3] PCI: Set pref for mem64 resource of pcie device

On Wed, Apr 8, 2015 at 8:17 PM, Benjamin Herrenschmidt
<benh@...nel.crashing.org> wrote:
> On Wed, 2015-04-08 at 17:06 -0700, Yinghai Lu wrote:

> I'll let Bjorn be the final judge here but I am not fan of the way you
> set/clear/set/clear the IORESOURCE_PREFETCH bit with
> pci_set_pref_under_pref(). It's error prone and confusing, the code is
> already barely readable as it is ...

We only use them to wrapping final pci_claim*, sizing, and assigning.
that is limited places.

>
> I would rather you replace those various masks compares with a helper
> that does something like pci_resource_compatible(parent_res, child_res),
> which has the logic to test. That or a helper that does something like
> pci_calc_compatible_res_flags() which returns a "flags" that has
> PREFETCH set, which you use in place of res->flags in the various
> allocation path.

That way should be more intrusive to current code, as we are using
type_mask checking to share the code among
parent(pref)/child(pref), parent(no-pref)/child(pref), and
parent(no-pref)/child(pref)

        Yinghai
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