On Sun, Jun 26, 2016 at 12:28 AM, Stephen Boyd [off-list ref] wrote:

The state of USB ChipIdea support on Qualcomm's platforms is not great.
The DT description of these devices requires up to three different nodes
for what amounts to be the same hardware block, when there should really
only be one. Furthermore, the "phy" driver that is in mainline (phy-msm-usb.c)
duplicates the OTG state machine and touches the ci controller wrapper
registers when it should really be focused on the phy and the ULPI accesses
needed to get the phy working. There's also a slimmed down phy driver for
the msm8916 platform, but really the phy hardware is the same as other MSMs,
so we have two drivers doing pretty much the same thing. This leads to a
situtaion where we have the chipidea core driver, the "phy" driver, and
sometimes the ehci-msm.c driver operating the same device all at the same
time with very little coordination. This just isn't very safe and is
confusing from a driver perspective when trying to figure out who does what.
Finally, there isn't any HSIC support on platforms like apq8074 so we
should add that.

This patch series updates the ChipIdea driver and the MSM wrapper
(ci_hdrc_msm.c) to properly handle the PHY and wrapper bits at the right
times in the right places. To get there, we update the ChipIdea core to
have support for the ULPI phy bus introduced by Heikki. Along the way
we fix bugs with the extcon handling for peripheral and OTG mode controllers
and move the parts of phy-usb-msm.c that are touching the CI controller
wrapper into the wrapper driver (ci_hdrc_msm.c). Finally we add support
for the HSIC phy based on the ULPI bus and rewrite the HS phy driver
(phy-usb-msm.c) as a standard ULPI phy driver.

Once this series is accepted, we should be able to delete the phy-usb-msm.c
phy-qcom-8x16-usb.c, and ehci-msm.c drivers from the tree and use the ULPI
based phy driver (which also lives in drivers/phy/ instead of drivers/usb/phy/)
and the chipidea host core instead.

I've also sent seperate patches for other minor pieces to make this
all work. The full tree can be found here[3], hacks and all to get
things working. I've tested this on the db410c, apq8074 dragonboard,
and ifc6410 with configfs gadgets and otg cables.

...

[3] https://git.linaro.org/people/stephen.boyd/linux.git/shortlog/refs/heads/usb-hsic-8074

Very excited to see this moving upstream!

Just a heads up, trying to build with this branch gives me:

drivers/usb/Kconfig:39:error: recursive dependency detected!
For a resolution refer to Documentation/kbuild/kconfig-language.txt
subsection "Kconfig recursive dependency limitations"
drivers/usb/Kconfig:39: symbol USB is selected by MOUSE_APPLETOUCH
For a resolution refer to Documentation/kbuild/kconfig-language.txt
subsection "Kconfig recursive dependency limitations"
drivers/input/mouse/Kconfig:187:        symbol MOUSE_APPLETOUCH depends on INPUT
For a resolution refer to Documentation/kbuild/kconfig-language.txt
subsection "Kconfig recursive dependency limitations"
drivers/input/Kconfig:8:        symbol INPUT is selected by VT
For a resolution refer to Documentation/kbuild/kconfig-language.txt
subsection "Kconfig recursive dependency limitations"
drivers/tty/Kconfig:12: symbol VT is selected by FB_STI
For a resolution refer to Documentation/kbuild/kconfig-language.txt
subsection "Kconfig recursive dependency limitations"
drivers/video/fbdev/Kconfig:674:        symbol FB_STI depends on FB
For a resolution refer to Documentation/kbuild/kconfig-language.txt
subsection "Kconfig recursive dependency limitations"
drivers/video/fbdev/Kconfig:5:  symbol FB is selected by DRM_KMS_FB_HELPER
For a resolution refer to Documentation/kbuild/kconfig-language.txt
subsection "Kconfig recursive dependency limitations"
drivers/gpu/drm/Kconfig:42:     symbol DRM_KMS_FB_HELPER is selected
by DRM_KMS_CMA_HELPER
For a resolution refer to Documentation/kbuild/kconfig-language.txt
subsection "Kconfig recursive dependency limitations"
drivers/gpu/drm/Kconfig:98:     symbol DRM_KMS_CMA_HELPER is selected by DRM_IMX
For a resolution refer to Documentation/kbuild/kconfig-language.txt
subsection "Kconfig recursive dependency limitations"
drivers/gpu/drm/imx/Kconfig:1:  symbol DRM_IMX depends on IMX_IPUV3_CORE
For a resolution refer to Documentation/kbuild/kconfig-language.txt
subsection "Kconfig recursive dependency limitations"
drivers/gpu/ipu-v3/Kconfig:1:   symbol IMX_IPUV3_CORE depends on
RESET_CONTROLLER
For a resolution refer to Documentation/kbuild/kconfig-language.txt
subsection "Kconfig recursive dependency limitations"
drivers/reset/Kconfig:4:        symbol RESET_CONTROLLER is selected by
USB_CHIPIDEA
For a resolution refer to Documentation/kbuild/kconfig-language.txt
subsection "Kconfig recursive dependency limitations"
drivers/usb/chipidea/Kconfig:1: symbol USB_CHIPIDEA depends on USB_EHCI_HCD
For a resolution refer to Documentation/kbuild/kconfig-language.txt
subsection "Kconfig recursive dependency limitations"
drivers/usb/host/Kconfig:84:    symbol USB_EHCI_HCD depends on USB
drivers/usb/chipidea/otg.c: In function ‘hw_write_otgsc’:
drivers/usb/chipidea/otg.c:120:2: warning: format ‘%x’ expects
argument of type ‘unsigned int’, but argument 3 has type ‘long
unsigned int’ [-Wformat]
drivers/usb/chipidea/otg.c:120:2: warning: format ‘%x’ expects
argument of type ‘unsigned int’, but argument 4 has type ‘long
unsigned int’ [-Wformat]

I haven't yet been able to test with this, as I need some other fixes
it seems too to deal with some of the iommu changes in my flo-WIP tree
(it can't find of_dma_configure), but will let you know how things
work once I have all that sorted.

thanks
-john
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