If a multi-function device's bandwidth is already limited when it is
enumerated, a message is logged only for function 0. By contrast, when
downtraining occurs after enumeration, a message is logged for all
functions. That's because the former uses pcie_report_downtraining(),
whereas the latter uses __pcie_print_link_status() (which doesn't filter
functions != 0). I am seeing this happen on a MacBookPro9,1 with a GPU
(function 0) and an integrated HDA controller (function 1).
Avoid this incongruence by calling pcie_report_downtraining() in both
cases.
Signed-off-by: Lukas Wunner <lukas@wunner.de>
Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>
Reviewed-by: Alexandru Gagniuc <alex.gagniuc@dellteam.com>
When booting a MacBookPro9,1, duplicate link downtraining messages are
logged for the devices directly attached to the two CPU-internal Root Ports
of the Core i7 3615QM: Once on device enumeration and once on enablement
of the bandwidth notification interrupt on the Root Ports.
Duplicate messages do not occur with Root Ports on the PCH and Downstream
Ports on the Thunderbolt controller: Only a single message is logged for
these, namely on device enumeration.
The reason for the duplicate messages is a stale interrupt in the Link
Status register of the 3615QM's internal Root Ports. Avoid by clearing the
interrupt before enabling it.
An alternative approach would be to clear the interrupt already on device
enumeration or to report link downtraining only if the speed has changed.
That way, link downtraining occurring between device enumeration and
enablement of the bandwidth notification interrupt could be caught.
However clearing stale interrupts before enabling them is a standard
operating procedure for any driver and keeping the two steps in one place
makes the code easier to follow.
Signed-off-by: Lukas Wunner <lukas@wunner.de>
Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>
Reviewed-by: Alexandru Gagniuc <alex.gagniuc@dellteam.com>
A threaded IRQ with a NULL handler does not work with level-triggered
interrupts. request_threaded_irq() will return an error:
genirq: Threaded irq requested with handler=NULL and !ONESHOT for irq 16
pcie_bw_notification: probe of 0000:00:1b.0:pcie010 failed with error -22
For level interrupts we need to silence the interrupt before exiting the
IRQ handler, so just clear the PCI_EXP_LNKSTA_LBMS bit there.
Fixes: e8303bb7a7 ("PCI/LINK: Report degraded links via link bandwidth notification")
Reported-by: Linus Torvalds <torvalds@linux-foundation.org>
Reported-by: Borislav Petkov <bp@suse.de>
Signed-off-by: Alexandru Gagniuc <mr.nuke.me@gmail.com>
Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>
A warning is generated when a PCIe device is probed with a degraded link,
but there was no similar mechanism to warn when the link becomes degraded
after probing. The Link Bandwidth Notification provides this mechanism.
Use the Link Bandwidth Management Interrupt to detect bandwidth changes,
and rescan the bandwidth, looking for the weakest point. This is the same
logic used in probe().
Signed-off-by: Alexandru Gagniuc <mr.nuke.me@gmail.com>
Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>
Reviewed-by: Lukas Wunner <lukas@wunner.de>
Lukas Wunner