Re: [PATCH v4 10/20] tegra: fdt: Add additional USB binding
From: Stephen Warren <hidden>
Date: 2012-01-18 22:48:30
Also in:
linux-tegra, u-boot
On 01/11/2012 09:32 PM, Simon Glass wrote:
quoted hunk
This adds a property to indicate a port which can switch between host and device mode. Signed-off-by: Simon Glass <redacted> --- doc/device-tree-bindings/usb/tegra-usb.txt | 4 ++++ 1 files changed, 4 insertions(+), 0 deletions(-)diff --git a/doc/device-tree-bindings/usb/tegra-usb.txt b/doc/device-tree-bindings/usb/tegra-usb.txt index 035d63d..96fd022 100644 --- a/doc/device-tree-bindings/usb/tegra-usb.txt +++ b/doc/device-tree-bindings/usb/tegra-usb.txt@@ -11,3 +11,7 @@ Required properties : - phy_type : Should be one of "ulpi" or "utmi". - nvidia,vbus-gpio : If present, specifies a gpio that needs to be activated for the bus to be powered. + +Optional properties: + - support-host-mode : If present then this peripheral can switch between + host and device mode
All of Tegra's USB ports support host mode, and it's the typical mode of operation. The TRM also indicates that all USB ports support device mode (possibly depending on the PHY type that's been selected for or attached to port). Port 2 explicitly doesn't support run-time switching, but by omission, ports 1 and 3 do. Hence, "support-host-mode" is not an accurate name, and doesn't match the description given either. I think that it'd be better to: * Add properties to explicitly specify whether the port is intended/allowed to operate (per board design) in each of host or device mode. * Default to static host mode if no properties are present. i.e.: +Optional properties: + - enable-host-mode : Indicate that the port is intended to operate in + host mode. + - enable-device-mode : Indicate that the port is intended to operate + in device mode. We should error out if both properties are set for USB 2, since it doesn't support run-time switching. Perhaps you can skip this error-checking for now since we aren't implementing device mode anywhere anyway... Then in the later patch in your series that was using support-host-mode, * Do VBUS detection only if both enable-host-mode and enable-device-mode are present. * Do VBUS GPIO enable if enable-host-mode is present (or assumed by default) and VBUS detection passed (if it ran). -- nvpublic