Hello Remi, On Wed, 22 May 2019 23:33:50 +0200 Remi Pommarel <repk@xxxxxxxxxxxx> wrote: > When configuring pcie reset pin from gpio (e.g. initially set by > u-boot) to pcie function this pin goes low for a brief moment > asserting the PERST# signal. Thus connected device enters fundamental > reset process and link configuration can only begin after a minimal > 100ms delay (see [1]). > > Because the pin configuration comes from the "default" pinctrl it is > implicitly configured before the probe callback is called: > > driver_probe_device() > really_probe() > ... > pinctrl_bind_pins() /* Here pin goes from gpio to PCIE reset > function and PERST# is asserted */ > ... > drv->probe() > > [1] "PCI Express Base Specification", REV. 4.0 > PCI Express, February 19 2014, 6.6.1 Conventional Reset > > Signed-off-by: Remi Pommarel <repk@xxxxxxxxxxxx> It is always a bit annoying to add another 100ms in the boot path, but I don't see an easy alternative solution, so: Acked-by: Thomas Petazzoni <thomas.petazzoni@xxxxxxxxxxx> Thomas -- Thomas Petazzoni, CTO, Bootlin Embedded Linux and Kernel engineering https://bootlin.com
