[PATCH] usb: usb251xb: Set boost value for up- and downstream ports

[PATCH] usb: usb251xb: Set boost value for up- and downstream ports

[Neumann, Bastian]

This patch adds devicetree properties to enable signal boosting on USB ports.

Signed-off-by: Bastian Neumann <bastian.neumann@dentsplysirona.com>
---
 .../devicetree/bindings/usb/usb251xb.txt      | 22 +++++++++++++
 drivers/usb/misc/usb251xb.c                   | 32 +++++++++++++++++--
 2 files changed, 52 insertions(+), 2 deletions(-)

diff --git a/Documentation/devicetree/bindings/usb/usb251xb.txt b/Documentation/devicetree/bindings/usb/usb251xb.txt
index 1a934eab175e..538ae49fc31d 100644
--- a/Documentation/devicetree/bindings/usb/usb251xb.txt
+++ b/Documentation/devicetree/bindings/usb/usb251xb.txt
@@ -68,6 +68,26 @@ Optional properties :
  - swap-dx-lanes : Specifies the ports which will swap the differential-pair
        (D+/D-), default is not-swapped.

+Electrical signal boosting
+The controller supplies a "boosting" functionality to drive up the USB
+electrical signals. This could result in non-USB compliant parameters
+(one example would be J/K level test). This should be <0x00> unless
+specific implementation issues requiew additional signal boosting to
+correct for deraded USB signaling levels:
+ - <0x00> : Normal electrical drive strength (no boost)
+ - <0x01> : Elevated drive strength low (~4% boost)
+ - <0x02> : Elevated drive strength medium (~8% boost)
+ - <0x03> : Elevated drive strength high (~12% boost)
+
+ - boost-up : USB electrical signaling drive strength boost for upstream port.
+ - boost-1 :  USB electrical signaling drive strength boost for port 1.
+ - boost-2 :  USB electrical signaling drive strength boost for port 2.
+ - boost-3 :  USB electrical signaling drive strength boost for port 3.
+ - boost-4 :  USB electrical signaling drive strength boost for port 4.
+ - boost-5 :  USB electrical signaling drive strength boost for port 5.
+ - boost-6 :  USB electrical signaling drive strength boost for port 6.
+ - boost-7 :  USB electrical signaling drive strength boost for port 7.
+
 Examples:
        usb2512b@2c {
                compatible = "microchip,usb2512b";
@@ -86,4 +106,6 @@ Examples:
                serial = "1234567890A";
                /* correct misplaced usb connectors on port 1,2 */
                swap-dx-lanes = <1 2>;
+               boost-up = <0x00>; /* no boost for upstream port */
+               boost-1 = <0x02>; /* medium boost on port 1 */
        };
diff --git a/drivers/usb/misc/usb251xb.c b/drivers/usb/misc/usb251xb.c index 04c4e3fed094..625106343d12 100644
--- a/drivers/usb/misc/usb251xb.c
+++ b/drivers/usb/misc/usb251xb.c
@@ -575,6 +575,36 @@ static int usb251xb_get_ofdata(struct usb251xb *hub,
                              (wchar_t *)hub->serial,
                              USB251XB_STRING_BUFSIZE);

+       hub->boost_up = USB251XB_DEF_BOOST_UP;
+       if (!of_property_read_u32(np, "boost-up",
+           &property_u32))
+               hub->boost_up |= (property_u32 << 0);
+
+       hub->boost_14 = USB251XB_DEF_BOOST_14;
+       if (!of_property_read_u32(np, "boost-1",
+           &property_u32))
+               hub->boost_14 |= (property_u32 << 0);
+       if (!of_property_read_u32(np, "boost-2",
+           &property_u32))
+               hub->boost_14 |= (property_u32 << 2);
+       if (!of_property_read_u32(np, "boost-3",
+           &property_u32))
+               hub->boost_14 |= (property_u32 << 4);
+       if (!of_property_read_u32(np, "boost-4",
+           &property_u32))
+               hub->boost_14 |= (property_u32 << 6);
+       hub->boost_57 = USB251XB_DEF_BOOST_57;
+       if (!of_property_read_u32(np, "boost-5",
+           &property_u32))
+               hub->boost_57 |= (property_u32 << 0);
+       if (!of_property_read_u32(np, "boost-6",
+           &property_u32))
+               hub->boost_57 |= (property_u32 << 2);
+       if (!of_property_read_u32(np, "boost-7",
+           &property_u32))
+               hub->boost_57 |= (property_u32 << 4);
+
+
        /*
         * The datasheet documents the register as 'Port Swap' but in real the
         * register controls the USB DP/DM signal swapping for each port.
@@ -587,8 +617,6 @@ static int usb251xb_get_ofdata(struct usb251xb *hub,
         * may be as soon as needed.
         */
        hub->bat_charge_en = USB251XB_DEF_BATTERY_CHARGING_ENABLE;
-       hub->boost_57 = USB251XB_DEF_BOOST_57;
-       hub->boost_14 = USB251XB_DEF_BOOST_14;
        hub->port_map12 = USB251XB_DEF_PORT_MAP_12;
        hub->port_map34 = USB251XB_DEF_PORT_MAP_34;
        hub->port_map56 = USB251XB_DEF_PORT_MAP_56;
--
2.30.2



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Sirona Dental Systems GmbH
Sitz der Gesellschaft / registered address: Fabrikstraße 31, 64625 Bensheim
Registergericht / court of registry: Amtsgericht Darmstadt, HRB 24948
Geschäftsführer / Managing Director: Dr. Cord Stähler, Jan Siefert, Rainer Raschke
Aufsichtsratsvorsitzender / Chairman of the Supervisory Board: Dr. Alexander Voelcker

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Re: [PATCH] usb: usb251xb: Set boost value for up- and downstream ports

[Krzysztof Kozlowski]

On 11/03/2022 11:04, Neumann, Bastian wrote:
> This patch adds devicetree properties to enable signal boosting on USB ports.
> 
> Signed-off-by: Bastian Neumann <bastian.neumann@dentsplysirona.com>
> ---
>  .../devicetree/bindings/usb/usb251xb.txt      | 22 +++++++++++++

Please split the bindings change. scripts/checkpatch did not complain?

You also need to Cc maintainers. Use scripts/get_maintainer.pl for this.

Read:
https://elixir.bootlin.com/linux/v5.13/source/Documentation/process/submitting-patches.rst

Best regards,
Krzysztof