Messages in this thread | | | Date | Mon, 7 Jul 2014 10:16:09 -0400 (EDT) | From | Alan Stern <> | Subject | Re: [PATCH v2 3/4] USB: EHCI: tegra: Fix probe order issue leading to broken USB |
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On Fri, 4 Jul 2014, Tuomas Tynkkynen wrote:
> The Tegra USB complex has a particularly annoying misdesign: some of the > UTMI pad configuration registers are global for all the 3 USB controllers > on the chip, but those registers are located in the first controller's > register space and will be cleared when the reset to the first > controller is asserted. Currently, this means that if the 1st controller > were to finish probing after the 2nd or 3rd controller, USB would not > work at all. > > Fix this situation by always resetting the 1st controller before doing > any other setup to any of the controllers, and then never ever reset the > first controller again. As the UTMI registers are related to the PHY, > the PHY driver should probably reset the Tegra controllers instead, > but since old device trees only have reset phandles in the EHCI nodes, > do it here, which means a bit of device tree groveling. Those old DTs > also won't get the reset fix from this commit, so we'll dev_warn() them, > but the driver will still keep probing successfully. > > Signed-off-by: Tuomas Tynkkynen <ttynkkynen@nvidia.com> > --- > v2 changes: assume we can find the usb1 reset from the PHY DT node, > don't fail if it's not found but just issue a warning > drivers/usb/host/ehci-tegra.c | 62 +++++++++++++++++++++++++++++++++++++++-- > 1 file changed, 59 insertions(+), 3 deletions(-)
Acked-by: Alan Stern <stern@rowland.harvard.edu>
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