lkml.org 
[lkml]   [2021]   [Sep]   [20]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
    Patch in this message
    /
    From
    Subject[PATCH 4.19 184/293] usb: gadget: composite: Allow bMaxPower=0 if self-powered
    Date
    From: Jack Pham <jackp@codeaurora.org>

    [ Upstream commit bcacbf06c891374e7fdd7b72d11cda03b0269b43 ]

    Currently the composite driver encodes the MaxPower field of
    the configuration descriptor by reading the c->MaxPower of the
    usb_configuration only if it is non-zero, otherwise it falls back
    to using the value hard-coded in CONFIG_USB_GADGET_VBUS_DRAW.
    However, there are cases when a configuration must explicitly set
    bMaxPower to 0, particularly if its bmAttributes also has the
    Self-Powered bit set, which is a valid combination.

    This is specifically called out in the USB PD specification section
    9.1, in which a PDUSB device "shall report zero in the bMaxPower
    field after negotiating a mutually agreeable Contract", and also
    verified by the USB Type-C Functional Test TD.4.10.2 Sink Power
    Precedence Test.

    The fix allows the c->MaxPower to be used for encoding the bMaxPower
    even if it is 0, if the self-powered bit is also set. An example
    usage of this would be for a ConfigFS gadget to be dynamically
    updated by userspace when the Type-C connection is determined to be
    operating in Power Delivery mode.

    Co-developed-by: Ronak Vijay Raheja <rraheja@codeaurora.org>
    Acked-by: Felipe Balbi <balbi@kernel.org>
    Signed-off-by: Ronak Vijay Raheja <rraheja@codeaurora.org>
    Signed-off-by: Jack Pham <jackp@codeaurora.org>
    Link: https://lore.kernel.org/r/20210720080907.30292-1-jackp@codeaurora.org
    Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
    Signed-off-by: Sasha Levin <sashal@kernel.org>
    ---
    drivers/usb/gadget/composite.c | 8 ++++++--
    1 file changed, 6 insertions(+), 2 deletions(-)

    diff --git a/drivers/usb/gadget/composite.c b/drivers/usb/gadget/composite.c
    index d85bb3ba8263..a76ed4acb570 100644
    --- a/drivers/usb/gadget/composite.c
    +++ b/drivers/usb/gadget/composite.c
    @@ -481,7 +481,7 @@ static u8 encode_bMaxPower(enum usb_device_speed speed,
    {
    unsigned val;

    - if (c->MaxPower)
    + if (c->MaxPower || (c->bmAttributes & USB_CONFIG_ATT_SELFPOWER))
    val = c->MaxPower;
    else
    val = CONFIG_USB_GADGET_VBUS_DRAW;
    @@ -891,7 +891,11 @@ static int set_config(struct usb_composite_dev *cdev,
    }

    /* when we return, be sure our power usage is valid */
    - power = c->MaxPower ? c->MaxPower : CONFIG_USB_GADGET_VBUS_DRAW;
    + if (c->MaxPower || (c->bmAttributes & USB_CONFIG_ATT_SELFPOWER))
    + power = c->MaxPower;
    + else
    + power = CONFIG_USB_GADGET_VBUS_DRAW;
    +
    if (gadget->speed < USB_SPEED_SUPER)
    power = min(power, 500U);
    else
    --
    2.30.2


    \
     
     \ /
      Last update: 2021-09-20 19:56    [W:4.104 / U:0.044 seconds]
    ©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site