PCI: Avoid broken MSI on SB600 USB devices
authorBjorn Helgaas <bhelgaas@google.com>
Mon, 21 Mar 2022 18:34:46 +0000 (13:34 -0500)
committerGreg Kroah-Hartman <gregkh@linuxfoundation.org>
Fri, 8 Apr 2022 12:23:42 +0000 (14:23 +0200)
commit40092a8ac089dbdaf13d50074b7d56b65e401868
treef98bf74436ea9279c058a3f3090b15581815cfd6
parentdd1043342e453913760b088e58a780e968674ace
PCI: Avoid broken MSI on SB600 USB devices

[ Upstream commit 63cd736f449445edcd7f0bcc7d84453e9beec0aa ]

Some ATI SB600 USB adapters advertise MSI, but if INTx is disabled by
setting PCI_COMMAND_INTX_DISABLE, MSI doesn't work either.  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.

Fixes: 306c54d0edb6 ("usb: hcd: Try MSI interrupts on PCI devices")
Link: https://lore.kernel.org/r/20220321183446.1108325-1-helgaas@kernel.org
Link: https://bugzilla.kernel.org/show_bug.cgi?id=215690
Link: https://lore.kernel.org/all/PxIByDyBRcsbpcmVhGSNDFAoUcMmb78ctXCkw6fbpx25TGlCHvA6SJjjFkNr1FfQZMntYPTNyvEnblxzAZ8a6jP9ddLpKeCN6Chi_2FuexU=@protonmail.com/
Link: https://lore.kernel.org/r/20220314101448.90074-1-andriy.shevchenko@linux.intel.com
BugLink: https://lore.kernel.org/all/20200702143045.23429-1-andriy.shevchenko@linux.intel.com/
Reported-by: Mick Lorain <micklorain@protonmail.com>
Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>
drivers/pci/quirks.c