Re: [PATCH] ARM: tegra: add device tree for SHIELD
From: Alexandre Courbot
Date: Wed Feb 26 2014 - 00:12:34 EST
On 02/26/2014 02:02 PM, Stephen Warren wrote:
On 02/25/2014 09:58 PM, Alexandre Courbot wrote:
On 02/26/2014 07:38 AM, Stephen Warren wrote:
On 02/24/2014 07:13 PM, Alexandre Courbot wrote:
On 02/25/2014 03:53 AM, Stephen Warren wrote:
On 02/24/2014 03:26 AM, Alexandre Courbot wrote:
Add a device tree for NVIDIA SHIELD. The set of enabled features is
still minimal with no display option (although HDMI should be easy
to get to work) and USB requiring external power.
...
For the Wifi chip, non-removable would be the correct setting
hardware-wise, but there is a trap: the chip has its reset line asserted
at boot-time, and you need to set GPIO 229 to de-assert it. Only after
that will the device be detected on the SDIO bus. Since it lacks a CD
line, it must be polled, hence the broken-cd property.
How does that GPIO get manipulated right now? I assume you must be
manually configuring it via sysfs after boot or something? If so,
perhaps it's best to just leave out the WiFi node until it works
automatically.
The GPIO needs to be set from user-space, yes. But if we leave the Wifi
node out, I'm concerned that wireless will not be usable at all,
wouldn't it?
True, but if we have no representation of the device in DT that works
without manually enabling clocks and/or GPIOs, it's not a
complete/accurate representation of the HW, so it doesn't make sense to
add it to DT. Yes, I admit that sucks.
Well, I can always enable it in my out-of-tree branch until we can push
the complete binding in mainline, so I'm ok with taking it out of this
patch for now.
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