linux-kernel - Re: [PATCH v9 10/15] ACPI: platform-msi: retrieve dev id from IORT

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Message-ID: <d620f35e-f335-bab5-49e0-a92375e00ea5@arm.com>
Date:   Wed, 29 Mar 2017 15:52:47 +0100
From:   Marc Zyngier <marc.zyngier@....com>
To:     Hanjun Guo <hanjun.guo@...aro.org>,
        Lorenzo Pieralisi <lorenzo.pieralisi@....com>
Cc:     Hanjun Guo <guohanjun@...wei.com>,
        "Rafael J. Wysocki" <rafael@...nel.org>,
        linux-acpi@...r.kernel.org, linux-arm-kernel@...ts.infradead.org,
        linux-kernel@...r.kernel.org, Thomas Gleixner <tglx@...utronix.de>,
        Greg KH <gregkh@...uxfoundation.org>,
        Tomasz Nowicki <tn@...ihalf.com>, Ma Jun <majun258@...wei.com>,
        Kefeng Wang <wangkefeng.wang@...wei.com>,
        Sinan Kaya <okaya@...eaurora.org>, huxinwei@...wei.com,
        yimin@...wei.com, linuxarm@...wei.com
Subject: Re: [PATCH v9 10/15] ACPI: platform-msi: retrieve dev id from IORT

On 29/03/17 14:00, Hanjun Guo wrote:
> On 03/29/2017 08:38 PM, Lorenzo Pieralisi wrote:
>> On Wed, Mar 29, 2017 at 07:52:48PM +0800, Hanjun Guo wrote:
>>> Hi Lorenzo,
>>>
>>> On 03/29/2017 06:14 PM, Lorenzo Pieralisi wrote:
>>>> Hi Hanjun, Marc,
>>>>
>>>> On Tue, Mar 07, 2017 at 08:40:05PM +0800, Hanjun Guo wrote:
>>>>> From: Hanjun Guo <hanjun.guo@...aro.org>
>>>>>
>>>>> For devices connecting to ITS, the devices need to identify themself
>>>>> through a dev id; this dev id is represented in the IORT table in named
>>>>> component node [1] for platform devices, so this patch adds code that
>>>>> scans the IORT table to retrieve the devices' dev id.
>>>>>
>>>>> Leveraging the iort_node_map_platform_id() IORT API, add a new function
>>>>> call, iort_pmsi_get_dev_id() and use it in its_pmsi_prepare() to allow
>>>>> retrieving dev id in ACPI platforms.
>>>>>
>>>>> [1]: https://static.docs.arm.com/den0049/b/DEN0049B_IO_Remapping_Table.pdf
>>>>>
>>>>> Signed-off-by: Hanjun Guo <hanjun.guo@...aro.org>
>>>>> [lorenzo.pieralisi@....com: rewrote commit log]
>>>>> Signed-off-by: Lorenzo Pieralisi <lorenzo.pieralisi@....com>
>>>>> Tested-by: Ming Lei <ming.lei@...onical.com>
>>>>> Tested-by: Wei Xu <xuwei5@...ilicon.com>
>>>>> Tested-by: Sinan Kaya <okaya@...eaurora.org>
>>>>> Cc: Marc Zyngier <marc.zyngier@....com>
>>>>> Cc: Lorenzo Pieralisi <lorenzo.pieralisi@....com>
>>>>> Cc: Tomasz Nowicki <tn@...ihalf.com>
>>>>> Cc: Thomas Gleixner <tglx@...utronix.de>
>>>>> ---
>>>>>   drivers/acpi/arm64/iort.c                     | 24 ++++++++++++++++++++++++
>>>>>   drivers/irqchip/irq-gic-v3-its-platform-msi.c |  3 ++-
>>>>>   include/linux/acpi_iort.h                     |  5 +++++
>>>>>   3 files changed, 31 insertions(+), 1 deletion(-)
>>>>
>>>> To simplify merging ACPI/IRQCHIP changes via different trees it
>>>> would be good to split this patch; I am not sure what's the best
>>>> way of handling it though given that we would end up in a merge
>>>> ordering dependency anyway (ie we can create an empty stub
>>>> for iort_pmsi_get_dev_id() but that would create a dependency
>>>> between ARM64 and irqchip trees anyway).
>>>
>>> The first 12 patches for ACPI platform MSI and later 3 patches
>>> for mbigen have no "physical" dependency, which means they can
>>> be merged and compiled independently, they only have functional
>>> dependency only.
>>>
>>> We already had SAS, XGE, USB and even UART drivers depend on
>>> the mbigen ACPI support, so I don't think the dependency of ACPI
>>> platform MSI and mbigen patches cares much if those two parts are
>>> merged in one merge window, even they are merged independently via
>>> different tree.
>>>
>>>>
>>>> Please let me know what's your preferred way of handling this.
>>>
>>> So in my opinion, they can be merged independently via ARM64 and
>>> irqchip tree with no ordering dependency, is it OK?
>>
>> I am speaking about merging MBIgen AND ITS patches via IRQCHIP and
>> ACPI/IORT for ARM64, that's why I replied to this patch. I do not
>> think that's feasible to split patches in two separate branches
>> without having a dependency between them.
>>
>> Sure, the last three patches can go via IRQCHIP but that was not
>> my question :)
> 
> Sorry, I misunderstood that :(
> 
> Since it's not feasible to split patches, the best way I got is that
> we get Marc's ack then merge it.

I believe there is a way to make this work without too much hassle. I
suggest we drop the ITS change from this patch entirely, and I instead
queue this patch:

https://git.kernel.org/pub/scm/linux/kernel/git/maz/arm-platforms.git/commit/?h=irq/irqchip-4.12&id=e6db07d0f3b6da1f8cfd485776bfefa4fcdbfc45

That way, no dependency between the two trees. Lorenzo takes all the
patches flagged "ACPI", I take all those flagged "irqchip" or "msi", and
everything should be perfectly standalone.

Thoughts?

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