From: Jack Pham <jackp@codeaurora.org>
To: Felipe Balbi <balbi@kernel.org>,
Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: linux-usb@vger.kernel.org
Subject: Re: [PATCH 2/2] usb: gadget: composite: Support more than 500mA MaxPower
Date: Wed, 23 Oct 2019 00:02:35 -0700 [thread overview]
Message-ID: <20191023070235.GA2257@jackp-linux.qualcomm.com> (raw)
In-Reply-To: <20191023065753.32722-2-jackp@codeaurora.org>
On Tue, Oct 22, 2019 at 11:57:53PM -0700, Jack Pham wrote:
> USB 3.x SuperSpeed peripherals can draw up to 900mA of VBUS power
> when in configured state. However, if a configuration wanting to
> take advantage of this is added with MaxPower greater than 500
> (currently possible if using a ConfigFS gadget) the composite
> driver fails to accommodate this for a couple reasons:
>
> - usb_gadget_vbus_draw() when called from set_config() and
> composite_resume() will be passed the MaxPower value without
> regard for the current connection speed, resulting in a
> violation for USB 2.0 since the max is 500mA.
>
> - the bMaxPower of the configuration descriptor would be
> incorrectly encoded, again if the connection speed is only
> at USB 2.0 or below, likely wrapping around UINT8_MAX since
> the 2mA multiplier corresponds to a maximum of 610mA.
^^^^^
Argh, my bad math/typo. Should be 510mA (UINT8_MAX = 255 * 2mA).
Jack
--
The Qualcomm Innovation Center, Inc. is a member of Code Aurora Forum,
a Linux Foundation Collaborative Project
next prev parent reply other threads:[~2019-10-23 7:02 UTC|newest]
Thread overview: 9+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-10-23 6:57 [PATCH 1/2] usb: gadget: composite: Fix bMaxPower for SuperSpeedPlus Jack Pham
2019-10-23 6:57 ` [PATCH 2/2] usb: gadget: composite: Support more than 500mA MaxPower Jack Pham
2019-10-23 7:02 ` Jack Pham [this message]
2019-10-23 7:49 ` Felipe Balbi
2019-10-23 8:31 ` jackp
2019-10-29 11:03 ` Felipe Balbi
2019-10-30 2:11 ` Jack Pham
2019-10-30 11:39 ` Felipe Balbi
2019-10-26 1:04 ` [PATCH v2 " Jack Pham
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=20191023070235.GA2257@jackp-linux.qualcomm.com \
--to=jackp@codeaurora.org \
--cc=balbi@kernel.org \
--cc=gregkh@linuxfoundation.org \
--cc=linux-usb@vger.kernel.org \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is an external index of several public inboxes,
see mirroring instructions on how to clone and mirror
all data and code used by this external index.