From mboxrd@z Thu Jan 1 00:00:00 1970 From: Stephen Warren Date: Tue, 5 Apr 2016 11:35:54 -0600 Subject: [U-Boot] [PATCH 1/8] usb: gadget: Move CONFIG_USB_GADGET_VBUS_DRAW to Kconfig In-Reply-To: <1459874197-14460-2-git-send-email-semen.protsenko@linaro.org> References: <1459874197-14460-1-git-send-email-semen.protsenko@linaro.org> <1459874197-14460-2-git-send-email-semen.protsenko@linaro.org> Message-ID: <5703F77A.5010407@wwwdotorg.org> List-Id: MIME-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit To: u-boot@lists.denx.de On 04/05/2016 10:36 AM, Semen Protsenko wrote: > From: Sam Protsenko > > The description was borrowed from kernel, but allowed range was changed > from 2..500 to 0..500, because some boards require this option to be 0. Do they /require/ the value to be 0, or simply currently have it set to 0 because whoever set the value in U-Boot wasn't aware that a value of 0 could cause issues with some hosts? I'd be tempted to keep the same range as the Linux kernel and bump all boards up to a minimum value of 2. Presumably there's some good reason the kernel chose a minimum of 2, and in practice I expect increasing all boards to 2 isn't going to make any negative difference. > diff --git a/drivers/usb/gadget/Kconfig b/drivers/usb/gadget/Kconfig > +config USB_GADGET_VBUS_DRAW > + int "Maximum VBUS Power usage (2-500 mA)" > + range 0 500 > + default 2 > + help > + Some devices need to draw power from USB when they are > + configured, perhaps to operate circuitry or to recharge > + batteries. This is in addition to any local power supply, > + such as an AC adapter or batteries. > + > + Enter the maximum power your device draws through USB, in > + milliAmperes. The permitted range of values is 2 - 500 mA; > + 0 mA would be legal, but can make some hosts misbehave. In particular, I'm thinking of that last sentence.