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

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Date:	Thu, 13 Nov 2014 20:55:38 +0800
From:	Yijing Wang <wangyijing@...wei.com>
To:	Jiang Liu <jiang.liu@...ux.intel.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 20:39, Jiang Liu wrote:
> 
> 
> 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.

OK, I thought we could use msi_desc to describe DMAR/HPET irq, so they could
share the mask/unmask, write_msg/read_etc.. But maybe it's not a right direction. :)

> 	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.

That's good :)


> 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(-)
>>>
>>
>>
> 
> .
> 


-- 
Thanks!
Yijing

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