On 29.08.2016 08:26, Lu Baolu wrote:
xHCI debug capability (DbC) is an optional but standalone functionality provided by an xHCI host controller. With DbC hardware initialized, the system will present a debug device through the USB3 debug port (normally the first USB3 port). The debug device is fully compliant with the USB framework and provides the equivalent of a very high performance (USB3) full-duplex serial link between the debug host and target. The DbC functionality is independent of xHCI host. There isn't any precondition from xHCI host side for DbC to work. This patch set adds support for early printk functionality through a USB3 debug port by 1) initializing and enabling the DbC hardware during early boot; 2) registering a boot console to the system so that early printk messages can go through the USB3 debug port. It also includes some lines of changes in usb_debug driver so that it can be bound when a USB3 debug device is enumerated. This is the resend version. Original patch set was submitted several months ago. This resend version addresses the review comment here [1]. [1] https://lkml.org/lkml/2016/2/16/444
So other than making sure memory is freed, (and maybe cleanup the duplicate code) I don't really have any objections. As you state in PATCH 1/4, this could be useful in the specific case of kernel debugging when machine crashes very early before the console code is initialized. For normal operation it is not recommended. And as it's not recommended or used for normal operations it shouldn't do any harm either -Mathias -- To unsubscribe from this list: send the line "unsubscribe linux-usb" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
