xhci is rock solid meanwhile.  So move it up in the docs and feature it
as prefered usb host adapter, instead of the old shy version saying "you
might want try ...".

While being at it rework the text on ehci and companion controllers too.

Signed-off-by: Gerd Hoffmann <kraxel@redhat.com>
---
 docs/usb2.txt | 80 ++++++++++++++++++++++++++++++++++-------------------------
 1 file changed, 46 insertions(+), 34 deletions(-)

diff --git a/docs/usb2.txt b/docs/usb2.txt
index 09df45b5b1..30055a2258 100644
--- a/docs/usb2.txt
+++ b/docs/usb2.txt
@@ -1,16 +1,42 @@
 
-USB 2.0 Quick Start
-===================
+USB Quick Start
+===============
 
-The QEMU EHCI Adapter can be used with and without companion
-controllers.  See below for the companion controller mode.
+xhci controller support
+-----------------------
 
-When not running in companion controller mode there are two completely
-separate USB busses: One USB 1.1 bus driven by the UHCI controller and
-one USB 2.0 bus driven by the EHCI controller.  Devices must be
-attached to the correct controller manually.
+Qemu has xhci host adapter support.  The xhci hardware design is much
+more virtualization-friendly when compared to ehci and uhci, thus xhci
+emulation uses less resources (especially cpu).  So if your guest
+supports xhci (which should be the case for any operating system
+released around 2010 or later) I recommend using it:
 
-The '-usb' switch will make qemu create the UHCI controller as part of
+    qemu -device qemu-xhci
+
+xhci supports USB 1.1, USB 2.0 and USB 3.0 devices, so this is the
+only controller you need.  With only a single usb controller (and
+therefore only a single usb bus) being present in the system there is
+no need to use the bus= parameter when adding usb devices.
+
+
+ehci controller support
+-----------------------
+
+The QEMU EHCI Adapter supports USB 2.0 devices.  It can be used either
+standalone or with companion controllers (UHCI, OHCI) for USB 1.1
+devices.  The companion controller setup is more convinient to use
+because it provides a single usb bus supporting both USB 2.0 and USB
+1.1 devices.  See next section for details.
+
+When running EHCI in standalone mode you can add UHCI or OHCI
+controllers for USB 1.1 devices too.  Each controller creates its own
+bus though, so there are two completely separate USB busses: One USB
+1.1 bus driven by the UHCI controller and one USB 2.0 bus driven by
+the EHCI controller.  Devices must be attached to the correct
+controller manually.
+
+The easiest way to add a UHCI controller to a 'pc' machine is the
+'-usb' switch, qemu will create the UHCI controller as function of
 the PIIX3 chipset.  The USB 1.1 bus will carry the name "usb-bus.0".
 
 You can use the standard -device switch to add a EHCI controller to
@@ -37,37 +63,23 @@ device to the EHCI adapter.
 Companion controller support
 ----------------------------
 
-Companion controller support has been added recently.  The operational
-model described above with two completely separate busses still works
-fine.  Additionally the UHCI and OHCI controllers got the ability to
-attach to a usb bus created by EHCI as companion controllers.  This is
-done by specifying the masterbus and firstport properties.  masterbus
-specifies the bus name the controller should attach to.  firstport
-specifies the first port the controller should attach to, which is
-needed as usually one ehci controller with six ports has three uhci
-companion controllers with two ports each.
+The UHCI and OHCI controllers can attach to a usb bus created by EHCI
+as companion controllers.  This is done by specifying the masterbus
+and firstport properties.  masterbus specifies the bus name the
+controller should attach to.  firstport specifies the first port the
+controller should attach to, which is needed as usually one ehci
+controller with six ports has three uhci companion controllers with
+two ports each.
 
-There is a config file in docs which will do all this for you, just
-try ...
+There is a config file in docs which will do all this for
+you, just try ...
 
     qemu -readconfig docs/config/ich9-ehci-uhci.cfg
 
 ... then use "bus=ehci.0" to assign your usb devices to that bus.
 
-
-xhci controller support
------------------------
-
-There is also xhci host controller support available.  It got a lot
-less testing than ehci and there are a bunch of known limitations, so
-ehci may work better for you.  On the other hand the xhci hardware
-design is much more virtualization-friendly, thus xhci emulation uses
-less resources (especially cpu).  If you want to give xhci a try
-use this to add the host controller ...
-
-    qemu -device nec-usb-xhci,id=xhci
-
-... then use "bus=xhci.0" when assigning usb devices.
+Using the '-usb' switch for 'q35' machines will create a simliar
+usb controller configuration.
 
 
 More USB tips & tricks
-- 
2.9.3

On 5 June 2018 at 13:52, Gerd Hoffmann <kraxel@redhat.com> wrote:
> xhci is rock solid meanwhile.  So move it up in the docs and feature it
> as prefered usb host adapter, instead of the old shy version saying "you
> might want try ...".
>
> While being at it rework the text on ehci and companion controllers too.
>
> Signed-off-by: Gerd Hoffmann <kraxel@redhat.com>
> ---
>  docs/usb2.txt | 80 ++++++++++++++++++++++++++++++++++-------------------------
>  1 file changed, 46 insertions(+), 34 deletions(-)


This is good; I did a quick pass-through for typos and the like.

> diff --git a/docs/usb2.txt b/docs/usb2.txt
> index 09df45b5b1..30055a2258 100644
> --- a/docs/usb2.txt
> +++ b/docs/usb2.txt
> @@ -1,16 +1,42 @@
>
> -USB 2.0 Quick Start
> -===================
> +USB Quick Start
> +===============
>
> -The QEMU EHCI Adapter can be used with and without companion
> -controllers.  See below for the companion controller mode.
> +xhci controller support
> +-----------------------
>
> -When not running in companion controller mode there are two completely
> -separate USB busses: One USB 1.1 bus driven by the UHCI controller and
> -one USB 2.0 bus driven by the EHCI controller.  Devices must be
> -attached to the correct controller manually.
> +Qemu has xhci host adapter support.  The xhci hardware design is much

"QEMU" should be all upper-case.

We also seem to be inconsistent about whether to uppercase UHCI,
EHCI and XHCI. I'd suggest using all-upper-case (except obviously
in QEMU device names like 'qemu-xhci').

> +more virtualization-friendly when compared to ehci and uhci, thus xhci
> +emulation uses less resources (especially cpu).  So if your guest
> +supports xhci (which should be the case for any operating system
> +released around 2010 or later) I recommend using it:

I think we should phrase our documentation from a project point
of view, so "we recommend" rather than "I".

>
> -The '-usb' switch will make qemu create the UHCI controller as part of
> +    qemu -device qemu-xhci
> +
> +xhci supports USB 1.1, USB 2.0 and USB 3.0 devices, so this is the
> +only controller you need.  With only a single usb controller (and
> +therefore only a single usb bus) being present in the system there is

s/being//

> +no need to use the bus= parameter when adding usb devices.
> +
> +
> +ehci controller support
> +-----------------------
> +
> +The QEMU EHCI Adapter supports USB 2.0 devices.  It can be used either
> +standalone or with companion controllers (UHCI, OHCI) for USB 1.1
> +devices.  The companion controller setup is more convinient to use

"convenient".

> +because it provides a single usb bus supporting both USB 2.0 and USB
> +1.1 devices.  See next section for details.
> +
> +When running EHCI in standalone mode you can add UHCI or OHCI
> +controllers for USB 1.1 devices too.  Each controller creates its own
> +bus though, so there are two completely separate USB busses: One USB

"buses". (the double-s spelling is a valid but less-used variant;
our docs mostly use the single-s spelling though, so we should
go with that for consistency.)

> +1.1 bus driven by the UHCI controller and one USB 2.0 bus driven by
> +the EHCI controller.  Devices must be attached to the correct
> +controller manually.
> +
> +The easiest way to add a UHCI controller to a 'pc' machine is the
> +'-usb' switch, qemu will create the UHCI controller as function of

s/, qemu/. QEMU/.

>  the PIIX3 chipset.  The USB 1.1 bus will carry the name "usb-bus.0".
>
>  You can use the standard -device switch to add a EHCI controller to
> @@ -37,37 +63,23 @@ device to the EHCI adapter.
>  Companion controller support
>  ----------------------------
>
> -Companion controller support has been added recently.  The operational
> -model described above with two completely separate busses still works
> -fine.  Additionally the UHCI and OHCI controllers got the ability to
> -attach to a usb bus created by EHCI as companion controllers.  This is
> -done by specifying the masterbus and firstport properties.  masterbus
> -specifies the bus name the controller should attach to.  firstport
> -specifies the first port the controller should attach to, which is
> -needed as usually one ehci controller with six ports has three uhci
> -companion controllers with two ports each.
> +The UHCI and OHCI controllers can attach to a usb bus created by EHCI
> +as companion controllers.  This is done by specifying the masterbus
> +and firstport properties.  masterbus specifies the bus name the
> +controller should attach to.  firstport specifies the first port the
> +controller should attach to, which is needed as usually one ehci
> +controller with six ports has three uhci companion controllers with
> +two ports each.
>
> -There is a config file in docs which will do all this for you, just
> -try ...
> +There is a config file in docs which will do all this for
> +you, just try ...
>
>      qemu -readconfig docs/config/ich9-ehci-uhci.cfg
>
>  ... then use "bus=ehci.0" to assign your usb devices to that bus.
>
> -
> -xhci controller support
> ------------------------
> -
> -There is also xhci host controller support available.  It got a lot
> -less testing than ehci and there are a bunch of known limitations, so
> -ehci may work better for you.  On the other hand the xhci hardware
> -design is much more virtualization-friendly, thus xhci emulation uses
> -less resources (especially cpu).  If you want to give xhci a try
> -use this to add the host controller ...
> -
> -    qemu -device nec-usb-xhci,id=xhci
> -
> -... then use "bus=xhci.0" when assigning usb devices.
> +Using the '-usb' switch for 'q35' machines will create a simliar

"similar".

> +usb controller configuration.
>

thanks
-- PMM