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From: Marc Zyngier <maz@kernel.org>
To: Frank Wunderlich <frank-w@public-files.de>
Cc: Ryder Lee <ryder.lee@mediatek.com>,
	linux-mediatek@lists.infradead.org,
	Thomas Gleixner <tglx@linutronix.de>,
	Frank Wunderlich <linux@fw-web.de>,
	linux-kernel@vger.kernel.org,
	Matthias Brugger <matthias.bgg@gmail.com>,
	linux-pci@vger.kernel.org, Bjorn Helgaas <bhelgaas@google.com>
Subject: Re: Aw: Re: [PATCH] pci: mediatek: fix warning in msi.h
Date: Sun, 01 Nov 2020 21:47:25 +0000	[thread overview]
Message-ID: <87k0v4u4uq.wl-maz@kernel.org> (raw)
In-Reply-To: <trinity-9eb2a213-f877-4af3-87df-f76a9c093073-1604255233122@3c-app-gmx-bap08>

On Sun, 01 Nov 2020 18:27:13 +0000,
Frank Wunderlich <frank-w@public-files.de> wrote:
> 
> > Gesendet: Sonntag, 01. November 2020 um 18:54 Uhr
> > Von: "Ryder Lee" <ryder.lee@mediatek.com>
> 
> > Yea, mt7623 (mtk_pcie_soc_v1) does not support MSI, so that's a way to
> > handle it.
> >
> > @Frank, could you help to test it?
> >
> > Ryder
> 
> compiles clean for mt7623/armhf and mt7622/aarch64 so far
> 
> at least bananapi-r2/mt7623 booting is clean now - no warning pcie
> and sata/ahci seems still working as expected. I have a mt7615 card
> in pcie-slot (firmware-load and init without errors) and hdd
> connected to outer sata port (can access partitions witout errors)
> 
> booted r64 too, still see no warning, but have not yet connected
> hdd/pcie-device, but i guess this should not break anything here
> 
> so Marc, if you post the patch separately, you can add my tested-by
> ;) thank you for this

Thinking of it a bit more, I think this is the wrong solution.

PCI MSIs are optional, and not a requirement. I can trivially spin a
VM with PCI devices and yet no MSI capability (yes, it is more
difficult with real HW), and this results in a bunch of warning, none
of which are actually indicative of anything being wrong.

I think the real fix is to get rid of the warnings altogether. If we
could detect that there should be an MSI domain associated with the
device and that it wasn't there, that'd be a good reason to scream.
But on its own, the absence of a MSI domain is not an indication of
anything being amiss.

	M.

-- 
Without deviation from the norm, progress is not possible.

WARNING: multiple messages have this Message-ID (diff)
From: Marc Zyngier <maz@kernel.org>
To: Frank Wunderlich <frank-w@public-files.de>
Cc: Ryder Lee <ryder.lee@mediatek.com>,
	linux-pci@vger.kernel.org, linux-kernel@vger.kernel.org,
	Bjorn Helgaas <bhelgaas@google.com>,
	linux-mediatek@lists.infradead.org,
	Matthias Brugger <matthias.bgg@gmail.com>,
	Thomas Gleixner <tglx@linutronix.de>,
	Frank Wunderlich <linux@fw-web.de>
Subject: Re: Aw: Re: [PATCH] pci: mediatek: fix warning in msi.h
Date: Sun, 01 Nov 2020 21:47:25 +0000	[thread overview]
Message-ID: <87k0v4u4uq.wl-maz@kernel.org> (raw)
In-Reply-To: <trinity-9eb2a213-f877-4af3-87df-f76a9c093073-1604255233122@3c-app-gmx-bap08>

On Sun, 01 Nov 2020 18:27:13 +0000,
Frank Wunderlich <frank-w@public-files.de> wrote:
> 
> > Gesendet: Sonntag, 01. November 2020 um 18:54 Uhr
> > Von: "Ryder Lee" <ryder.lee@mediatek.com>
> 
> > Yea, mt7623 (mtk_pcie_soc_v1) does not support MSI, so that's a way to
> > handle it.
> >
> > @Frank, could you help to test it?
> >
> > Ryder
> 
> compiles clean for mt7623/armhf and mt7622/aarch64 so far
> 
> at least bananapi-r2/mt7623 booting is clean now - no warning pcie
> and sata/ahci seems still working as expected. I have a mt7615 card
> in pcie-slot (firmware-load and init without errors) and hdd
> connected to outer sata port (can access partitions witout errors)
> 
> booted r64 too, still see no warning, but have not yet connected
> hdd/pcie-device, but i guess this should not break anything here
> 
> so Marc, if you post the patch separately, you can add my tested-by
> ;) thank you for this

Thinking of it a bit more, I think this is the wrong solution.

PCI MSIs are optional, and not a requirement. I can trivially spin a
VM with PCI devices and yet no MSI capability (yes, it is more
difficult with real HW), and this results in a bunch of warning, none
of which are actually indicative of anything being wrong.

I think the real fix is to get rid of the warnings altogether. If we
could detect that there should be an MSI domain associated with the
device and that it wasn't there, that'd be a good reason to scream.
But on its own, the absence of a MSI domain is not an indication of
anything being amiss.

	M.

-- 
Without deviation from the norm, progress is not possible.

_______________________________________________
Linux-mediatek mailing list
Linux-mediatek@lists.infradead.org
http://lists.infradead.org/mailman/listinfo/linux-mediatek

  reply	other threads:[~2020-11-01 21:47 UTC|newest]

Thread overview: 62+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-10-31 14:03 [PATCH] pci: mediatek: fix warning in msi.h Frank Wunderlich
2020-10-31 14:03 ` Frank Wunderlich
2020-10-31 21:49 ` Thomas Gleixner
2020-10-31 21:49   ` Thomas Gleixner
2020-11-01  9:25   ` Frank Wunderlich
2020-11-01  9:25     ` Frank Wunderlich
2020-11-01 11:17     ` Thomas Gleixner
2020-11-01 11:17       ` Thomas Gleixner
2020-11-01 11:43     ` Marc Zyngier
2020-11-01 11:43       ` Marc Zyngier
2020-11-01 15:58       ` Aw: " Frank Wunderlich
2020-11-01 15:58         ` Frank Wunderlich
2020-11-01 17:54       ` Ryder Lee
2020-11-01 17:54         ` Ryder Lee
2020-11-01 18:27         ` Aw: " Frank Wunderlich
2020-11-01 18:27           ` Frank Wunderlich
2020-11-01 21:47           ` Marc Zyngier [this message]
2020-11-01 21:47             ` Marc Zyngier
2020-11-01 22:27             ` Thomas Gleixner
2020-11-01 22:27               ` Thomas Gleixner
2020-11-02 11:30               ` Marc Zyngier
2020-11-02 11:30                 ` Marc Zyngier
2020-11-02 11:56                 ` Aw: " Frank Wunderlich
2020-11-02 11:56                   ` Frank Wunderlich
2020-11-02 13:58                   ` Marc Zyngier
2020-11-02 13:58                     ` Marc Zyngier
2020-11-02 14:27                     ` Aw: " Frank Wunderlich
2020-11-02 14:27                       ` Frank Wunderlich
2020-11-02 16:16                 ` Aw: " Thomas Gleixner
2020-11-02 16:16                   ` Thomas Gleixner
2020-11-02 22:18                   ` Thomas Gleixner
2020-11-02 22:18                     ` Thomas Gleixner
2020-11-03  9:54                     ` Marc Zyngier
2020-11-03  9:54                       ` Marc Zyngier
2020-11-03 10:16                       ` Thomas Gleixner
2020-11-03 10:16                         ` Thomas Gleixner
2020-11-03 10:29                         ` Marc Zyngier
2020-11-03 10:29                           ` Marc Zyngier
2020-11-04 16:49                         ` Aw: " Frank Wunderlich
2020-11-04 16:49                           ` Frank Wunderlich
2020-11-04 23:14                           ` Thomas Gleixner
2020-11-04 23:14                             ` Thomas Gleixner
2020-11-05  9:20                             ` Marc Zyngier
2020-11-05  9:20                               ` Marc Zyngier
2020-11-05 13:59                               ` Aw: " Frank Wunderlich
2020-11-05 13:59                                 ` Frank Wunderlich
2020-11-05 23:00                               ` Aw: " Thomas Gleixner
2020-11-05 23:00                                 ` Thomas Gleixner
2020-11-06  9:43                                 ` Marc Zyngier
2020-11-06  9:43                                   ` Marc Zyngier
2020-11-21 16:12                                   ` Aw: " Frank Wunderlich
2020-11-21 16:12                                     ` Frank Wunderlich
2021-01-03 13:08                                     ` Frank Wunderlich
2021-01-03 13:08                                       ` Frank Wunderlich
2021-02-02 16:21                                   ` Frank Wunderlich
2021-02-02 16:21                                     ` Frank Wunderlich
2020-11-03 10:31                       ` Aw: " Thomas Gleixner
2020-11-03 10:31                         ` Thomas Gleixner
2020-11-03 11:41                         ` Marc Zyngier
2020-11-03 11:41                           ` Marc Zyngier
2020-11-03 14:23                           ` Thomas Gleixner
2020-11-03 14:23                             ` Thomas Gleixner

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