RE: [patch 17/20] platform-msi: Switch to the domain id aware MSI interfaces

From: "Tian, Kevin" <kevin.tian@intel.com>
To: Thomas Gleixner <tglx@linutronix.de>,
	LKML <linux-kernel@vger.kernel.org>
Cc: "x86@kernel.org" <x86@kernel.org>, Joerg Roedel <joro@8bytes.org>,
	"Will Deacon" <will@kernel.org>,
	"linux-pci@vger.kernel.org" <linux-pci@vger.kernel.org>,
	Bjorn Helgaas <bhelgaas@google.com>,
	"Lorenzo Pieralisi" <lorenzo.pieralisi@arm.com>,
	Marc Zyngier <maz@kernel.org>,
	"Greg Kroah-Hartman" <gregkh@linuxfoundation.org>,
	Jason Gunthorpe <jgg@mellanox.com>,
	"Jiang, Dave" <dave.jiang@intel.com>,
	Alex Williamson <alex.williamson@redhat.com>,
	"Williams, Dan J" <dan.j.williams@intel.com>,
	Logan Gunthorpe <logang@deltatee.com>,
	"Raj, Ashok" <ashok.raj@intel.com>, Jon Mason <jdmason@kudzu.us>,
	Allen Hubbe <allenbh@gmail.com>,
	"Ahmed S. Darwish" <darwi@linutronix.de>,
	"Chatre, Reinette" <reinette.chatre@intel.com>
Subject: RE: [patch 17/20] platform-msi: Switch to the domain id aware MSI interfaces
Date: Mon, 21 Nov 2022 03:42:20 +0000	[thread overview]
Message-ID: <BN9PR11MB5276EB567D822DA9148BEB3A8C0A9@BN9PR11MB5276.namprd11.prod.outlook.com> (raw)
In-Reply-To: <87fsegjvn3.ffs@tglx>

> From: Thomas Gleixner <tglx@linutronix.de>
> Sent: Friday, November 18, 2022 8:27 PM
> 
> On Fri, Nov 18 2022 at 08:53, Kevin Tian wrote:
> >> From: Thomas Gleixner <tglx@linutronix.de>
> >>
> >> -	err = msi_domain_alloc_irqs(dev->msi.domain, dev, nvec);
> >> +	err = msi_domain_alloc_irqs_range(dev, MSI_DEFAULT_DOMAIN, 0,
> >> nvec - 1);
> >>  	if (err)
> >>  		platform_msi_free_priv_data(dev);
> >>
> >
> > Out of curiosity. Why don't we provide an unlocked version of
> > msi_domain_alloc_irqs_all()?
> 
> -ENOUSER

msi_domain_alloc_irqs() and msi_domain_alloc_irqs_descs_locked()
are a pair.

What I didn't get was why the unlocked invocation in this patch
is replaced by a range-based helper while the locked invocation
in previous patch16 was replaced by an all-based helper:

	if (domain && irq_domain_is_hierarchy(domain))
-		return msi_domain_alloc_irqs_descs_locked(domain, &dev->dev, nvec);
+		return msi_domain_alloc_irqs_all_locked(&dev->dev, MSI_DEFAULT_DOMAIN, nvec);

The reason could probably be marked out in the commit msg.