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When DWC3 is set to host mode by programming register DWC3_GCTL, VBUS (or its control signal) will be turned on immediately on related Root Hub ports. Then, the VBUS is turned off for a little while(15us) when do xhci reset (conducted by xhci driver) and back to normal finally, we can observe a negative glitch of related signal happen. This VBUS glitch might cause some USB devices enumeration fail if kernel boot with them connected. Such as LS1012AFWRY/LS1043ARDB/LX2160AQDS /LS1088ARDB with Kingston 16GB USB2.0/Kingston USB3.0/JetFlash Transcend 4GB USB2.0 drives. The fail cases include enumerated as full-speed device or report wrong device descriptor, etc. One SW workaround which can fix this is by programing all xhci PORTSC[PP] to 0 to turn off VBUS immediately after setting host mode in DWC3 driver (per signal measurement result, it will be too late to do it in xhci-plat.c or xhci.c). Then, after xhci reset complete in xhci driver, PORTSC[PP]s' value will back to 1 automatically and VBUS on at that time, no glitch happen and normal enumeration process has no impact. Acked-by: Thinh Nguyen <Thinh.Nguyen@synopsys.com> Signed-off-by: Ran Wang <ran.wang_1@nxp.com> Reviewed-by: Peter Chen <peter.chen@nxp.com> Signed-off-by: Frank Li <Frank.Li@nxp.com> Link: https://lore.kernel.org/r/20240124152525.3910311-4-Frank.Li@nxp.com Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> |
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arch | ||
block | ||
certs | ||
crypto | ||
Documentation | ||
drivers | ||
fs | ||
include | ||
init | ||
io_uring | ||
ipc | ||
kernel | ||
lib | ||
LICENSES | ||
mm | ||
net | ||
rust | ||
samples | ||
scripts | ||
security | ||
sound | ||
tools | ||
usr | ||
virt | ||
.clang-format | ||
.cocciconfig | ||
.editorconfig | ||
.get_maintainer.ignore | ||
.gitattributes | ||
.gitignore | ||
.mailmap | ||
.rustfmt.toml | ||
COPYING | ||
CREDITS | ||
Kbuild | ||
Kconfig | ||
MAINTAINERS | ||
Makefile | ||
README |
Linux kernel ============ There are several guides for kernel developers and users. These guides can be rendered in a number of formats, like HTML and PDF. Please read Documentation/admin-guide/README.rst first. In order to build the documentation, use ``make htmldocs`` or ``make pdfdocs``. The formatted documentation can also be read online at: https://www.kernel.org/doc/html/latest/ There are various text files in the Documentation/ subdirectory, several of them using the Restructured Text markup notation. Please read the Documentation/process/changes.rst file, as it contains the requirements for building and running the kernel, and information about the problems which may result by upgrading your kernel.