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author | Linus Torvalds <torvalds@linux-foundation.org> | 2009-09-23 09:25:16 -0700 |
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committer | Linus Torvalds <torvalds@linux-foundation.org> | 2009-09-23 09:25:16 -0700 |
commit | be90a49ca22a95f184d9f32d35b5247b44032849 (patch) | |
tree | d3c2edc18c003c384366f57901616ac29c80bc27 /Documentation/x86/earlyprintk.txt | |
parent | 1f0918d03ff4b5c94540c71ce889672abdbc2f4a (diff) | |
parent | a87371b477774b290c27bc5cb7f4ccc5379574a9 (diff) | |
download | talos-op-linux-be90a49ca22a95f184d9f32d35b5247b44032849.tar.gz talos-op-linux-be90a49ca22a95f184d9f32d35b5247b44032849.zip |
Merge git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/usb-2.6
* git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/usb-2.6: (142 commits)
USB: Fix sysfs paths in documentation
USB: skeleton: fix coding style issues.
USB: O_NONBLOCK in read path of skeleton
USB: make usb-skeleton honor O_NONBLOCK in write path
USB: skel_read really sucks royally
USB: Add hub descriptor update hook for xHCI
USB: xhci: Support USB hubs.
USB: xhci: Set multi-TT field for LS/FS devices under hubs.
USB: xhci: Set route string for all devices.
USB: xhci: Fix command wait list handling.
USB: xhci: Change how xHCI commands are handled.
USB: xhci: Refactor input device context setup.
USB: xhci: Endpoint representation refactoring.
USB: gadget: ether needs to select CRC32
USB: fix USBTMC get_capabilities success handling
USB: fix missing error check in probing
USB: usbfs: add USBDEVFS_URB_BULK_CONTINUATION flag
USB: support for autosuspend in sierra while online
USB: ehci-dbgp,ehci: Allow dbpg to work with suspend/resume
USB: ehci-dbgp,documentation: Documentation updates for ehci-dbgp
...
Diffstat (limited to 'Documentation/x86/earlyprintk.txt')
-rw-r--r-- | Documentation/x86/earlyprintk.txt | 39 |
1 files changed, 37 insertions, 2 deletions
diff --git a/Documentation/x86/earlyprintk.txt b/Documentation/x86/earlyprintk.txt index 607b1a016064..f19802c0f485 100644 --- a/Documentation/x86/earlyprintk.txt +++ b/Documentation/x86/earlyprintk.txt @@ -7,7 +7,7 @@ and two USB cables, connected like this: [host/target] <-------> [USB debug key] <-------> [client/console] -1. There are three specific hardware requirements: +1. There are a number of specific hardware requirements: a.) Host/target system needs to have USB debug port capability. @@ -42,7 +42,35 @@ and two USB cables, connected like this: This is a small blue plastic connector with two USB connections, it draws power from its USB connections. - c.) Thirdly, you need a second client/console system with a regular USB port. + c.) You need a second client/console system with a high speed USB 2.0 + port. + + d.) The Netchip device must be plugged directly into the physical + debug port on the "host/target" system. You cannot use a USB hub in + between the physical debug port and the "host/target" system. + + The EHCI debug controller is bound to a specific physical USB + port and the Netchip device will only work as an early printk + device in this port. The EHCI host controllers are electrically + wired such that the EHCI debug controller is hooked up to the + first physical and there is no way to change this via software. + You can find the physical port through experimentation by trying + each physical port on the system and rebooting. Or you can try + and use lsusb or look at the kernel info messages emitted by the + usb stack when you plug a usb device into various ports on the + "host/target" system. + + Some hardware vendors do not expose the usb debug port with a + physical connector and if you find such a device send a complaint + to the hardware vendor, because there is no reason not to wire + this port into one of the physically accessible ports. + + e.) It is also important to note, that many versions of the Netchip + device require the "client/console" system to be plugged into the + right and side of the device (with the product logo facing up and + readable left to right). The reason being is that the 5 volt + power supply is taken from only one side of the device and it + must be the side that does not get rebooted. 2. Software requirements: @@ -56,6 +84,13 @@ and two USB cables, connected like this: (If you are using Grub, append it to the 'kernel' line in /etc/grub.conf) + On systems with more than one EHCI debug controller you must + specify the correct EHCI debug controller number. The ordering + comes from the PCI bus enumeration of the EHCI controllers. The + default with no number argument is "0" the first EHCI debug + controller. To use the second EHCI debug controller, you would + use the command line: "earlyprintk=dbgp1" + NOTE: normally earlyprintk console gets turned off once the regular console is alive - use "earlyprintk=dbgp,keep" to keep this channel open beyond early bootup. This can be useful for |