On Fri, Jan 12, 2018 at 4:12 AM, Arnd Bergmann <arnd@xxxxxxxx> wrote: > Stefan Wahren reports a problem with a warning fix that was merged > for v4.15: we had lots of device nodes with a 'phys' property pointing > to a device node that is not compliant with the binding documented in > Documentation/devicetree/bindings/phy/phy-bindings.txt > > This generally works because USB HCD drivers that support both the generic > phy subsystem and the older usb-phy subsystem ignore most errors from > phy_get() and related calls and then use the usb-phy driver instead. > > However, it turns out that making the usb-nop-xceiv device compatible with > the generic-phy binding changes the phy_get() return code from -EINVAL to > -EPROBE_DEFER, and the dwc2 usb controller driver for bcm2835 now returns > -EPROBE_DEFER from its probe function rather than ignoring the failure, > breaking all USB support on raspberry-pi when CONFIG_GENERIC_PHY is > enabled. The same code is used in the dwc3 driver and the usb_add_hcd() > function, so a reasonable assumption would be that many other platforms > are affected as well. > > I have reviewed all the related patches and concluded that "usb-nop-xceiv" > is the only USB phy that is affected by the change, and since it is by far > the most commonly referenced phy, all the other USB phy drivers appear > to be used in ways that are are either safe in DT (they don't use the > 'phys' property), or in the driver (they already ignore -EPROBE_DEFER > from generic-phy when usb-phy is available). > > To work around the problem, this adds a special case to _of_phy_get() > so we ignore any PHY node that is compatible with "usb-nop-xceiv", > as we know that this can never load no matter how much we defer. In the > future, we might implement a generic-phy driver for "usb-nop-xceiv" > and then remove this workaround. > > Since we generally want older kernels to also want to work with the > fixed devicetree files, it would be good to backport the patch into > stable kernels as well (3.13+ are possibly affected), even though they > don't contain any of the patches that may have caused regressions. > > Fixes: 014d6da6cb25 ARM: dts: bcm283x: Fix DTC warnings about missing phy-cells > Fixes: c5bbf358b790 arm: dts: nspire: Add missing #phy-cells to usb-nop-xceiv > Fixes: 44e5dced2ef6 arm: dts: marvell: Add missing #phy-cells to usb-nop-xceiv > Fixes: f568f6f554b8 ARM: dts: omap: Add missing #phy-cells to usb-nop-xceiv > Fixes: d745d5f277bf ARM: dts: imx51-zii-rdu1: Add missing #phy-cells to usb-nop-xceiv > Fixes: 915fbe59cbf2 ARM: dts: imx: Add missing #phy-cells to usb-nop-xceiv > Link: https://marc.info/?l=linux-usb&m=151518314314753&w=2 > Link: https://patchwork.kernel.org/patch/10158145/ > Cc: stable@xxxxxxxxxxxxxxx > Cc: Stefan Wahren <stefan.wahren@xxxxxxxx> > Cc: Felipe Balbi <balbi@xxxxxxxxxx> > Cc: Eric Anholt <eric@xxxxxxxxxx> > Tested-by: Hans Verkuil <hans.verkuil@xxxxxxxxx> > Acked-by: Kishon Vijay Abraham I <kishon@xxxxxx> > Signed-off-by: Arnd Bergmann <arnd@xxxxxxxx> > --- > Hans tested the earlier version of this patch, I'd like one more > confirmation from Hans or Stefan (or anyone else) that this version > addresses the regression as well before this gets merged. > > Greg, can you pick this up into usb-linus for v4.15 once the fix > has been confirmed, or should I merge it through arm-soc? > --- > drivers/phy/phy-core.c | 4 ++++ > 1 file changed, 4 insertions(+) Thanks for fixing this. Acked-by: Rob Herring <robh@xxxxxxxxxx> Rob -- To unsubscribe from this list: send the line "unsubscribe devicetree" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
