linux-kernel - Re: [Patch V1 0/6] Refine generic/PCI MSI irqodmian interfaces

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Message-ID: <5464A68E.4010004@linux.intel.com>
Date:	Thu, 13 Nov 2014 20:39:42 +0800
From:	Jiang Liu <jiang.liu@...ux.intel.com>
To:	Yijing Wang <wangyijing@...wei.com>,
	Bjorn Helgaas <bhelgaas@...gle.com>,
	Thomas Gleixner <tglx@...utronix.de>,
	Ingo Molnar <mingo@...hat.com>,
	Grant Likely <grant.likely@...aro.org>,
	Marc Zyngier <marc.zyngier@....com>,
	Yingjoe Chen <yingjoe.chen@...iatek.com>,
	Borislav Petkov <bp@...en8.de>,
	"H. Peter Anvin" <hpa@...or.com>,
	Matthias Brugger <matthias.bgg@...il.com>
CC:	Tony Luck <tony.luck@...el.com>, linux-kernel@...r.kernel.org,
	linux-pci@...r.kernel.org, linux-arm-kernel@...ts.infradead.org
Subject: Re: [Patch V1 0/6] Refine generic/PCI MSI irqodmian interfaces



On 2014/11/13 20:28, Yijing Wang wrote:
> On 2014/11/13 19:43, Jiang Liu wrote:
>> This patch set is based on tip/irq/irqdomain and tries to refine
>> interfaces to support irqdomain for generic MSI and PCI MSI.
>>
>> Patch 1 is just minor fixes for tip/irq/irqdomain.
>>
>> Patch 2 introduces some helpers to hide struct msi_desc implementation
>> details, so later we could move msi_list from struct pci_dev into
>> struct device to enable generic MSI support.
> 
> Hi Gerry,
>    I tried to move msi info(eg. msi_list) into struct device, but I found
> DMAR fault interrupt is initialized before the driver core init. And I don't
> know whether there are other devices like ARM consolidator(introduced in GIC v3)
> need to be initialized before driver core. What do you think about this ?
Hi Yijing,
	DMAR interrupt doesn't make use of msi_desc, so has no
dependency on msi_list.
	Actually there are two levels of generic MSI sharing. The first
level is to share common irq_chip/irqdomain code, such as HPET, DMAR and
HT_IRQ. The second level is to share msi_desc, such as some device
on ARM side as you have mentioned.
	With this patch set applied, we achieve level one sharing. For
level two sharing, we need to move msi_list into struct device, refactor
struct msi_desc, and provide a generic pci_enable_msix_range alike
user interfaces. I'm still working on this part, so we could cooperate
with each other.
Thanks!
Gerry

> 
> Thanks!
> Yijing.
> 
>>
>> Patch 3 introduces msi_domain_{alloc|free}_irqs() which generalize
>> pci_msi_domain_alloc_irqs() to support generic MSI.
>>
>> Patch 4 introduces default data structures and callback implementations
>> to support msi_domain_alloc_irqs(), so reduce burden on generic MSI
>> users.
>>
>> Patch 5 converts PCI MSI to use generic MSI interfaces, and also
>> implement default callbacks for PCI MSI.
>>
>> Patch 6 introduces a mechanism to replace arch_setup_msi_irq()/
>> arch_setup_msi_irqs()/arch_teardown_msi_irq()/arch_teardown_msi_irqs().
>>
>> With this patch set applied, the generic MSI and PCI MSI interfaces
>> are much easier to use. For extreme case, you only need to define
>> a "struct msi_domain_info" and don't need to implement any callbacks,
>> just using the default callbacks is OK:)
>>
>> This patch set is also a preparation for:
>> 1) Kill all weak functions in drivers/pci/msi.c
>> 2) Implement support for non-PCI-compliant MSI device
>>
>> It has been tested on x86 platforms, comments are welcomed!
>>
>> Jiang Liu (6):
>>   PCI, MSI: Fix errors caused by commit e5f1a59c4e12
>>   PCI, MSI: Introduce helpers to hide struct msi_desc implemenation
>>     details
>>   genirq: Introduce msi_domain_{alloc|free}_irqs()
>>   genirq: Provide default callbacks for msi_domain_ops
>>   PCI, MSI: Refine irqdomain interfaces to simplify its usage
>>   PCI, MSI: Provide mechanism to alloc/free MSI/MSIX interrupt from
>>     irqdomain
>>
>>  drivers/pci/msi.c   |  170 ++++++++++++++++++++++++++++++++++++++++-----------
>>  include/linux/msi.h |   90 ++++++++++++++++++++++++---
>>  kernel/irq/msi.c    |  150 ++++++++++++++++++++++++++++++++++++++++++++-
>>  3 files changed, 366 insertions(+), 44 deletions(-)
>>
> 
> 
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