On Thu, Mar 25, 2021 at 2:19 PM Stephen Boyd <swb...@chromium.org> wrote: > > Quoting Saravana Kannan (2021-03-02 13:11:32) > > This reverts commit 3e4c982f1ce75faf5314477b8da296d2d00919df. > > > > Since all reported issues due to fw_devlink=on should be addressed by > > this series, revert the revert. fw_devlink=on Take II. > > > > Signed-off-by: Saravana Kannan <sarava...@google.com> > > --- > > This seems to break the display on lazor (see > arch/arm64/boot/dts/qcom/sc7180-trogdor.dtsi) on linux next today > (next-20210325). I tried booting with fw_devlink=permissive on the > commandline and the display came up again. Looking at the drivers that > are in the deferred state there are three: > > localhost ~ # cat /sys/kernel/debug/devices_deferred > ae94000.dsi > panel > 2-002d > > and the panel has these suppliers: > > localhost ~ # ls /sys/devices/platform/panel/ > driver_override power > supplier:platform:pp3300-dx-edp-regulator > modalias subsystem uevent > of_node supplier:i2c:2-002d waiting_for_supplier > > Is there some sort of circular dependency going on that is preventing > either driver from probing? My understanding is 2-002d is the dsi bridge > (compatible is ti,sn65dsi86) and that is waiting for the panel to come > up, and the panel does a circular dependency where it requests the hpd > gpio from the dsi bridge at probe but then ignores it and tries to get > the hpd gpio later when powering on the panel. If it didn't do this it > would probe defer forever because the bridge supplies the hpd gpio to > the panel and the panel provides the panel to the bridge driver.
I had a side chat with Stephen. The problem is due to a cycle of dependency between panel and bridge (supplier:i2c:2-002d). panel needs GPIO from bridge, and bridge has panel as a remote-endpoint. But fw_delink isn't able to break the cycle because it doesn't parse "remote-endpoint" yet. So for now, only permissive will work for this case. I'll look into adding remote-endpoint support. But that's a bit more complicated. -Saravana > > > drivers/base/core.c | 2 +- > > 1 file changed, 1 insertion(+), 1 deletion(-) > > > > diff --git a/drivers/base/core.c b/drivers/base/core.c > > index 45c75cc96fdc..de518178ac36 100644 > > --- a/drivers/base/core.c > > +++ b/drivers/base/core.c > > @@ -1538,7 +1538,7 @@ static void device_links_purge(struct device *dev) > > #define FW_DEVLINK_FLAGS_RPM (FW_DEVLINK_FLAGS_ON | \ > > DL_FLAG_PM_RUNTIME) > > > > -static u32 fw_devlink_flags = FW_DEVLINK_FLAGS_PERMISSIVE; > > +static u32 fw_devlink_flags = FW_DEVLINK_FLAGS_ON; > > static int __init fw_devlink_setup(char *arg) > > { > > if (!arg)