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Manivannan SadhasivamandKonrad Dybcio
19c8b5ea3b
In the recent times, devicetree started to represent the PCI Host bridge
supplies like PHY in the Root Port nodes as seen in commit 38fcbfbd42
("dt-bindings: PCI: qcom: Move PHY & reset GPIO to Root Port node"). But
the Host bridge drivers still need to control these supplies as a part of
their controller initialization/deinitialization sequence.
So the Host bridge drivers end up parsing the Root Port supplies in their
probe() and controlled them. A downside to this approach is that the
devlink dependency between the suppliers and Host bridge is completely
broken. Due to this, the driver core probes the Host bridge drivers even if
the suppliers are not ready, causing probe deferrals and setup teardowns in
probe().
These probe deferrals sometime happen over 1000 times (as reported in Qcom
Glymur platform) leading to a waste of CPU resources and increase in boot
time. So to fix these unnecessary deferrals, create devlink between the
Host bridge and Root Port suppliers in of_fwnode_add_links(). This will
allow the driver core to probe the Host bridge drivers only when all Root
Port suppliers are available.
Reported-by: Bjorn Andersson <andersson@kernel.org>
Signed-off-by: Manivannan Sadhasivam <manivannan.sadhasivam@oss.qualcomm.com>