Re: [PATCH v3] PCI: Xilinx-NWL-PCIe: Added support for Xilinx NWL PCIe Host Controller

From: Marc Zyngier <marc.zyngier@arm.com>
To: Bharat Kumar Gogada <bharat.kumar.gogada@xilinx.com>,
	"robh+dt@kernel.org" <robh+dt@kernel.org>,
	"pawel.moll@arm.com" <pawel.moll@arm.com>,
	"mark.rutland@arm.com" <mark.rutland@arm.com>,
	"ijc+devicetree@hellion.org.uk" <ijc+devicetree@hellion.org.uk>,
	"galak@codeaurora.org" <galak@codeaurora.org>,
	Michal Simek <michals@xilinx.com>,
	Soren Brinkmann <sorenb@xilinx.com>,
	"bhelgaas@google.com" <bhelgaas@google.com>,
	"arnd@arndb.de" <arnd@arndb.de>,
	"tinamdar@apm.com" <tinamdar@apm.com>,
	"treding@nvidia.com" <treding@nvidia.com>,
	"rjui@broadcom.com" <rjui@broadcom.com>,
	"Minghuan.Lian@freescale.com" <Minghuan.Lian@freescale.com>,
	"m-karicheri2@ti.com" <m-karicheri2@ti.com>,
	"hauke@hauke-m.de" <hauke@hauke-m.de>
Cc: "devicetree@vger.kernel.org" <devicetree@vger.kernel.org>,
	"linux-pci@vger.kernel.org" <linux-pci@vger.kernel.org>,
	"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
	Ravikiran Gummaluri <rgummal@xilinx.com>,
	"linux-arm-kernel@lists.infradead.org" 
	<linux-arm-kernel@lists.infradead.org>
Subject: Re: [PATCH v3] PCI: Xilinx-NWL-PCIe: Added support for Xilinx NWL PCIe Host Controller
Date: Fri, 09 Oct 2015 09:10:17 +0100	[thread overview]
Message-ID: <56177669.2000302@arm.com> (raw)
In-Reply-To: <8520D5D51A55D047800579B09414719801690CD0@XAP-PVEXMBX01.xlnx.xilinx.com>

On 09/10/15 06:11, Bharat Kumar Gogada wrote:
>>>> +struct nwl_msi {                  /* struct nwl_msi - MSI information
>> */
>>>> +  struct msi_controller chip;     /* chip: MSI controller */
>>>
>>>> We're moving away from msi_controller altogether, as the kernel now
>>>> has all the necessary infrastructure to do this properly.
>>>
>>> Our current GIC version does not have separate msi controller (we are
>>> not using GICv2m or GICv3), so is it necessary to have separate msi
>>> controller node ? Please give me clarity on this.
>>
>> This has nothing to do with the version of the GIC you are using (XGene
>> doesn't have GICv2m or v3 either). This is about reducing code duplication
>> and having something that we can maintain. See also
>> https://lkml.org/lkml/2015/9/20/193 for yet another example.
>>
>> I still plan to kill msi_controller, and I'd like to avoid more dependencies with
>> it. MSI domains are the way to do it.
>>
> Sorry previously I haven't configured my email client properly so resending.

Thanks for doing so, much appreciated.

> Since we don't have separate MSI controller, and our PCIe controller
> is handling MSI, is it necessary to create a separate MSI controller
> node because we don't have any 'reg' space.

No, your PCI controller can perfectly be part of the PCIe node.

> Please let me know whether we require a separate msi file as
> suggested in your previous comments to separate MSI controller and
> PCIE controller in two files, if we don't have separate node. If we
> do not need a separate node do we need to embed MSI controller child
> node  in PCIe controller node itself, and what properties does this
> child node will require other than 'interrupts'.

If you want to keep them in the same file, please at least have two
separate patches. These are two different functions, and they should be
reviewed separately.

It will help everyone to understand your code, and speed up the
reviewing process.

Thanks,

	M.
-- 
Jazz is not dead. It just smells funny...