From: David Lechner <david@lechnology.com>
To: ahaslam@baylibre.com, gregkh@linuxfoundation.org,
robh+dt@kernel.org, nsekhar@ti.com, stern@rowland.harvard.edu,
khilman@baylibre.com, sshtylyov@ru.mvista.com
Cc: linux-usb@vger.kernel.org, devicetree@vger.kernel.org,
linux-kernel@vger.kernel.org,
linux-arm-kernel@lists.infradead.org
Subject: Re: [PATCH/RFT 07/12] USB: ohci-da8xx: Request gpios and handle interrupt in the driver
Date: Mon, 10 Oct 2016 18:18:46 -0500 [thread overview]
Message-ID: <22f1532a-b651-3330-b2ce-9a64a35c85af@lechnology.com> (raw)
In-Reply-To: <1475858577-10366-8-git-send-email-ahaslam@baylibre.com>
On 10/07/2016 11:42 AM, ahaslam@baylibre.com wrote:
> From: Axel Haslam <ahaslam@baylibre.com>
>
> Currently requesting the vbus and overcurrent gpio is handled on
> the board specific file. But this does not play well moving to
> device tree.
>
> In preparation to migrate to a device tree boot, handle requesting
> gpios and overcurrent interrupt on the usb driver itself, thus avoiding
> callbacks to arch/mach*
>
Instead of using gpios, it seems like it would be better to use a
regulator here. I don't know of any real-life cases, but who is to say
someone will not design a board that uses a regulator controlled by I2C
instead of gpios or something like that.
Then, boards that don't have gpios can just use a fixed regulator (or
you can make the regulator optional). Using a regulator would also allow
users to decide how to respond to overcurrent events (by supplying their
own regulator driver) instead of the behavior being dictated by the ohci
driver.
In my particular area of interest (LEGO MINDSTORMS EV3), the 5V
(hardware) regulator for VBUS does use gpios, but the 5V is also shared
with the LEGO input and output ports. So what I would ultimately like to
be able to do is have userspace notified of an overcurrent event and let
userspace decided when to turn the vbus back on. For example, someone
might plug something into one of the LEGO input or output ports that
causes a short circuit. I would like to display a notification to the
user and wait for them to correct the problem and then press a button to
turn the power back on.
This will require some modifications to the regulator subsystem though.
I actually started work on this a while back, but haven't had the time
to pursue it any farther.
Here are my WIP patches in case there is any interest:
*
https://github.com/dlech/ev3dev-kernel/commit/541a42b3b8ed639e95bbc835df3292f80190c789
*
https://github.com/dlech/ev3dev-kernel/commit/2ba99b1ad6a06c944dd33a073f54044e71b75ae6
*
https://github.com/dlech/ev3dev-kernel/commit/cdb03caa50e64931d4f2836c648739aa4385ed3b
*
https://github.com/dlech/ev3dev-kernel/commit/9d6b50cde34b51309c74d97c26b1430c7ff6aa0f
next prev parent reply other threads:[~2016-10-10 23:18 UTC|newest]
Thread overview: 20+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-10-07 16:42 [PATCH/RFT 00/12] Add DT support for ohci-da8xx ahaslam
2016-10-07 16:42 ` [PATCH/RFT 01/12] ARM: davinci: da8xx: Enable the usb20 "per" clk on phy_clk_enable ahaslam
2016-10-07 16:42 ` [PATCH/RFT 02/12] ARM: davinci: hawk: add full constraints for ohci plat boot ahaslam
2016-10-07 16:42 ` [PATCH/RFT 03/12] ARM: davinci: rename root_hub to platform_data ahaslam
2016-10-07 16:42 ` [PATCH/RFT 04/12] USB: ohci-da8xx: Divide power up time in the ohci driver ahaslam
2016-10-07 16:42 ` [PATCH/RFT 05/12] USB: ohci-da8xx: Fix probe for devices with no vbus/oci gpio ahaslam
2016-10-07 16:42 ` [PATCH/RFT 06/12] ARM: davinci: hawk: Remove oci and vbus gpios ahaslam
2016-10-07 16:42 ` [PATCH/RFT 07/12] USB: ohci-da8xx: Request gpios and handle interrupt in the driver ahaslam
2016-10-10 23:18 ` David Lechner [this message]
2016-10-12 15:01 ` Axel Haslam
2016-10-12 23:31 ` David Lechner
2016-10-07 16:42 ` [PATCH/RFT 08/12] ARM: davinci: register the usb20_phy clock on the SoC file ahaslam
2016-10-10 23:27 ` David Lechner
2016-10-07 16:42 ` [PATCH/RFT 09/12] usb: host: ohci-da8xx: Add devicetree bindings documentation ahaslam
2016-10-10 21:35 ` Rob Herring
2016-10-10 23:33 ` David Lechner
2016-10-07 16:42 ` [PATCH/RFT 10/12] USB: ohci-da8xx: Add device tree support ahaslam
2016-10-07 16:42 ` [PATCH/RFT 11/12] ARM: dts: da850: Add the usb ohci device node ahaslam
2016-10-07 17:11 ` Sergei Shtylyov
2016-10-07 16:42 ` [PATCH/RFT 12/12] ARM: dts: da850-lcdk: enable ohci usb ahaslam
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