From: Andy Shevchenko <andy.shevchenko@gmail.com>
To: Bjorn Helgaas <helgaas@kernel.org>
Cc: linux-pci <linux-pci@vger.kernel.org>,
Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
Mick Lorain <micklorain@protonmail.com>,
Alex Williamson <alex.williamson@redhat.com>,
Thomas Gleixner <tglx@linutronix.de>,
Bjorn Helgaas <bhelgaas@google.com>
Subject: Re: [PATCH] PCI: Avoid broken MSI on SB600 USB devices
Date: Wed, 23 Mar 2022 10:03:38 +0200 [thread overview]
Message-ID: <CAHp75VfdoAbSTkO7eaor94pkmN0ttLXstc1DS_Sa7i45Dt5GAA@mail.gmail.com> (raw)
In-Reply-To: <20220323022648.GA1243295@bhelgaas>
On Wed, Mar 23, 2022 at 4:26 AM Bjorn Helgaas <helgaas@kernel.org> wrote:
> On Mon, Mar 21, 2022 at 01:34:46PM -0500, Bjorn Helgaas wrote:
> > From: Bjorn Helgaas <bhelgaas@google.com>
> >
> > Some ATI SB600 USB adapters advertise MSI, but if INTx is disabled by
> > setting PCI_COMMAND_INTX_DISABLE,
> > MSI doesn't work either.
I think this is not correct.
> > The PCI/PCIe
> > specs do not require software to set PCI_COMMAND_INTX_DISABLE when enabling
> > MSI, but Linux has done that for many years.
> >
> > Mick reported that 306c54d0edb6 ("usb: hcd: Try MSI interrupts on PCI
> > devices") broke these devices. Prior to 306c54d0edb6, they used INTx.
> > Starting with 306c54d0edb6, they use MSI, and and the fact that Linux sets
> > PCI_COMMAND_INTX_DISABLE means both INTx and MSI are disabled on these
> > devices.
> > Avoid this SB600 defect by disabling MSI so we use INTx as before.
And this is kinda too conservative approach.
> > Fixes: 306c54d0edb6 ("usb: hcd: Try MSI interrupts on PCI devices")
> > Link: https://bugzilla.kernel.org/show_bug.cgi?id=215690
> > Link: https://lore.kernel.org/all/PxIByDyBRcsbpcmVhGSNDFAoUcMmb78ctXCkw6fbpx25TGlCHvA6SJjjFkNr1FfQZMntYPTNyvEnblxzAZ8a6jP9ddLpKeCN6Chi_2FuexU=@protonmail.com/
> > BugLink: https://lore.kernel.org/all/20200702143045.23429-1-andriy.shevchenko@linux.intel.com/
> > Link: https://lore.kernel.org/r/20220314101448.90074-1-andriy.shevchenko@linux.intel.com
> > Reported-by: Mick Lorain <micklorain@protonmail.com>
> > Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>
And it hasn't been tested by the reporter.
> Unless there's objection, I plan to include this in the v5.18 pull
> request in the next few days.
You are the maintainer here and it's your choice. I'm not going to stop you.
--
With Best Regards,
Andy Shevchenko
next prev parent reply other threads:[~2022-03-23 8:04 UTC|newest]
Thread overview: 8+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-03-21 18:34 [PATCH] PCI: Avoid broken MSI on SB600 USB devices Bjorn Helgaas
2022-03-23 2:26 ` Bjorn Helgaas
2022-03-23 8:03 ` Andy Shevchenko [this message]
2022-03-23 11:11 ` Bjorn Helgaas
2022-03-23 12:23 ` Andy Shevchenko
2022-03-23 12:43 ` David Woodhouse
2022-03-23 13:23 ` Bjorn Helgaas
2022-03-23 13:43 ` Andy Shevchenko
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