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 a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).