[PATCH] introduce-usb-host-power-control.patch

[Andy Green]

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Somebody in the thread at some point said:
> On Tue, Mar 11, 2008 at 09:25:41PM +0000, Andy Green wrote:
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>> Hm... I didn't find any support for this in the kernel... I didn't see
>> it in U-Boot...  either I missed the point badly or we don't seem to
>> have tested this?  It seems to work fine anyway.
> 
> Actually this should be done automatically, again based on id_pin
> status.

We still need a /sys node for the "automatic" thread to assert the
state, well at least if it is a usermode daemon.

> I'm inlining your patch below for commenting on it.
> 
> BTW, try using git send-email for that.
> The patch becomes a lot better for handling with git later ;-)
> also easier to review as it come inlined in the mail ;-)

These come inlined on Thunderbird, but point taken.

>> introduce-usb-host-power-control.patch
>>
>> From: Andy Green <andy at openmoko.com>
>>
>> Unless I really really missed the point, there is no support for enabling
>> USB Host power for USB host mode.  This patch adds a /sys node for GTA02
>> that allows control of the charge pump for 5V out on the USB mini connector
>> It doesn't change any logical mode in the CPU, just enables (1) and disables
>> (0) USB host power.
>>
>> # cat /sys/devices/platform/neo1973-pm-host.0/hostmode
>> 0
>> # echo 1 > /sys/devices/platform/neo1973-pm-host.0/hostmode
> 
> this should really be under ohci-s3c....

Hum however ohci-s3c does not know about pcm50633 -- btw there is a big
problem there as you said for 50606.c as far as upstream goes, it has
all kinds of illegal knowledge about GTA02 in there.  So we need to
stitch it through platform if that is the way, well, okay.

>> +static struct platform_device gta02_pm_usbhost_dev = {
>> +	.name		= "neo1973-pm-host",
>> +};
>> +
> 
> I don't really like this approach. You should just have something
> sampling id pin and when it goes grounded then you switch charge pump
> on.

Hum.  Right now it seems nobody ever tested the USB host pump or indeed
USB host on GTA02 -- I wired up a cable last night and it detected a USB
memory stick ok so it seems to work.  So this approach as of today at
least lets us control the EN_USBHOST net that configures the hardware to
host.  Being able to control EN_USBHOST separate from anything else may
have value for test too.

Also this just follows a trend of having broken out power management
"devices" as for bt and gsm.

Lastly we discussed what that "something" should be monitoring the ID
pin analogue level and the answer came back a daemon IIRC.  Therefore
the daemon needs a way to actually change the hardware configuration,
and a /sys node like this will do that in a clean way.  If we make it a
kernel thread, then no need, but we lose the ability to control it from
userspace which can be good.

>> + * Bluetooth PM code for the FIC Neo1973 GSM Phone
> 
> Err... USB ??

Yeah it was late.

>> +	pcf50633_gpio_set(pcf50633_global, PCF50633_GPO, on);
> 
> ahaa... so it's gpio-based.
> How about puting a gpio_request() call in ohci (or maybe board files)
> module for this device ?

Hm well no it is not CPU GPIO but GPIO on the PMU device, which is not
related directly to s3c*.  So yes it means stitching it through platform
to get it in s3c ohci, but we can do that.

>> +	dev_info(&pdev->dev, "starting\n");
> 
> this could be dev_dbg(), this message is only useful on debugging
> purposes, also something more explanatory would be cool :-)
> 
> something like:
> 
> dev_dbg(&pdev->dev, "Neo1973 USB PM\n");

dev_* prepends it with the device name, so it's clear enough who is
talking I think.

> how about:
> if (machine_is_neo1973_gta01())
> 	return -EINVAL;

Yeah.

> If you don't mind, I'd really like to redesign this. Tomorrow I
> scheduled to start coding linux-moko-2.6 as off now I just did the
> Makefile changes.

Generally if someone started on a patch, they should own subsequent
revisions.  However in this case, we already had you owning this region,
I jumped in on it because of another thread about USB host on another
list and that I realized nobody tested USB host power on GTA02.  So if
you want to redo along the lines you mention, go ahead.  In the
meanwhile I'll keep this patch in my git tree until it is replaced by
your implementation.

> I'll start putting together some board-files and the basic support,
> after that I'll start fixing up mokopatches to make them acceptable on
> mailine :-)

Heroic action, sir.

- -Andy
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