[PATCH V3 2/5] ARM: dts: bcm283x: Add dtsi for USB host mode
stefan.wahren at i2se.com
Mon Aug 22 13:18:15 PDT 2016
> Eric Anholt <eric at anholt.net> hat am 22. August 2016 um 19:57 geschrieben:
> Stefan Wahren <stefan.wahren at i2se.com> writes:
> > In case dr_mode isn't passed via DT, the dwc2 defaults to OTG mode.
> > But all Raspberry Pi boards here are designed only for host mode.
> > So fix this issue by providing a dtsi file which set the dr_mode
> > to host.
> Can you explain what change this should cause for these boards? Is it
> just going to drop this message from dmesg:
> dwc2 3f980000.usb: Configuration mismatch. dr_mode forced to host
IMO it isn't a message which could be ignored. The dwc2 tries to detected the
USB role from compile configuration and hardware capabilities, but according to
the decision table  we should provide the correct dr_mode which is import for
FIFO configuration and so on.
Another problem that i see is that the USB behavior is influenced by compile
settings in a unexpected way. With arm/configs/bcm2835_defconfig the driver is
forced to host, but in a multiplatform config like arm64/configs/defconfig not.
I would expect a more stable dr_mode.
At the end the dwc2 can't reliable detect the dr_mode because it depends on the
> or something else?
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