Re: [linux-sunxi] Re: [PATCH 4/5] ARM: dts: sun5i: Add dts file for the Empire Electronix D709 tablet

2016-01-04 Thread Maxime Ripard 
Hi,

On Tue, Dec 22, 2015 at 12:29:24PM +0800, Chen-Yu Tsai wrote:
> >>> So this means enabled the sdio controller (should be safe on all
> >>> boards?)  and enabling 2 regulators to power the wifi-chip. I
> >>> think it will be safe to do this even on boards where those
> >>> regulators are not used, what do you think ?
> >>
> >> Wouldn't that introduce some useless power drain on those boards?
> >
> >
> > If nothing is attached to those regulators (which I expect to be
> > the case when they are not used to power wifi) then I would expect
> > the drain to be minimal, my biggest worry is some board having
> > tied these to ground, but I don't think that is very likely.
> 
> AFAIK the AXP datasheets mention that unused DCDC outputs should be left
> floating. Not sure if this applies to LDO outputs as well. But any used
> outputs would have a bypass capacitor.
> 
> From the board designs I've seen, this seems to be the common case.
> I'm not an electrical engineer, but I think we're covered here.

Ok, I guess we're good then.

Thanks!
Maxime

-- 
Maxime Ripard, Free Electrons
Embedded Linux, Kernel and Android engineering
http://free-electrons.com


signature.asc
Description: Digital signature

Re: [linux-sunxi] Re: [PATCH 4/5] ARM: dts: sun5i: Add dts file for the Empire Electronix D709 tablet

2015-12-22 Thread Hans de Goede 

Hi,

On 22-12-15 05:29, Chen-Yu Tsai wrote:

On Tue, Dec 22, 2015 at 3:36 AM, Hans de Goede  wrote:

Hi,

On 21-12-15 17:11, Maxime Ripard wrote:


Hi,x

On Mon, Dec 21, 2015 at 11:46:18AM +0100, Hans de Goede wrote:


On the side, any thoughts on how to handle the differences between
various "Q8"
tablets, like different I2C-based sensors and WiFi chips?



For i2c based sensors the plan is to use devicetree overlays + an in
kernel
overlay manager which probes the i2c bus (checking known touchscreen /
accelerometer
addresses) and then picks the right touchscreen + accelerometer overlays.

Wifi is somewhat more tricky I must admit, esp. since there seem to be q8
a23 based
tablet variants with usb wifi and others with sdio wifi. Since both
busses are
discoverable I'm tempted to just enable both in devicetree, and let the
kernel probe
and see what is actually there. This assume that the way the wifichip is
powered
is the same on all boards, or at least that it is safe to enable the
necessary
regulators on all boards ...


I'm asking because with Maxime's couple-regulator we should be able to
get the
RTL8723BS on the Q8 A23/33 v1.5 working.



So this means enabled the sdio controller (should be safe on all boards?)
and
enabling 2 regulators to power the wifi-chip. I think it will be safe to
do this
even on boards where those regulators are not used, what do you think ?



Wouldn't that introduce some useless power drain on those boards?



If nothing is attached to those regulators (which I expect to be the case
when
they are not used to power wifi) then I would expect the drain to be
minimal,
my biggest worry is some board having tied these to ground, but I don't
think
that is very likely.


AFAIK the AXP datasheets mention that unused DCDC outputs should be left
floating. Not sure if this applies to LDO outputs as well. But any used
outputs would have a bypass capacitor.

 From the board designs I've seen, this seems to be the common case.
I'm not an electrical engineer, but I think we're covered here.

Another thing we need to deal with is the different power sequencing
requirements for the different SDIO chips.


In my experience there are not that much sequences, as simply making sure
all necessary resources are one before probing the sdio bus, I have yet to
see a case where the order in which the resources are enabled matters.

Regards,

Hans
--
To unsubscribe from this list: send the line "unsubscribe devicetree" in
the body of a message to majord...@vger.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html

Re: [linux-sunxi] Re: [PATCH 4/5] ARM: dts: sun5i: Add dts file for the Empire Electronix D709 tablet

2015-12-21 Thread Hans de Goede 

Hi,

On 21-12-15 17:11, Maxime Ripard wrote:

Hi,x

On Mon, Dec 21, 2015 at 11:46:18AM +0100, Hans de Goede wrote:

On the side, any thoughts on how to handle the differences between various "Q8"
tablets, like different I2C-based sensors and WiFi chips?


For i2c based sensors the plan is to use devicetree overlays + an in kernel
overlay manager which probes the i2c bus (checking known touchscreen / 
accelerometer
addresses) and then picks the right touchscreen + accelerometer overlays.

Wifi is somewhat more tricky I must admit, esp. since there seem to be q8 a23 
based
tablet variants with usb wifi and others with sdio wifi. Since both busses are
discoverable I'm tempted to just enable both in devicetree, and let the kernel 
probe
and see what is actually there. This assume that the way the wifichip is powered
is the same on all boards, or at least that it is safe to enable the necessary
regulators on all boards ...


I'm asking because with Maxime's couple-regulator we should be able to get the
RTL8723BS on the Q8 A23/33 v1.5 working.


So this means enabled the sdio controller (should be safe on all boards?) and
enabling 2 regulators to power the wifi-chip. I think it will be safe to do this
even on boards where those regulators are not used, what do you think ?


Wouldn't that introduce some useless power drain on those boards?


If nothing is attached to those regulators (which I expect to be the case when
they are not used to power wifi) then I would expect the drain to be minimal,
my biggest worry is some board having tied these to ground, but I don't think
that is very likely.

Regards,

Hans
--
To unsubscribe from this list: send the line "unsubscribe devicetree" in
the body of a message to majord...@vger.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html

Re: [linux-sunxi] Re: [PATCH 4/5] ARM: dts: sun5i: Add dts file for the Empire Electronix D709 tablet

2015-12-21 Thread Hans de Goede 

Hi,

On 21-12-15 07:09, Chen-Yu Tsai wrote:

Hi,

On Sun, Dec 20, 2015 at 7:43 PM, Hans de Goede  wrote:

The Empire Electronix D709 tablet is a fairly standard 7" A13 tablet,
featuring usb-wifi, a micro-sd slot, micro-usb otg and headphone jack.

Empire Electronix is written on the back of the tablet, the D709 model
info can be found in the about tablet menu in android.

The PCB has no markings to speak of.

This dts file does not add support for the ft5x touchscreen found at
i2c bus 1, addr 0x38, irq PG11, because it does not work out of the box.
It seems it has been flashed with the wrong firmware and needs to have
alternative firmware uploaded at boot to make the touchscreen work
properly, when hot-booting from android into an upstream kernel the
touchscreen does work.

The Memsic MXC622X accelerometer at i2c bus 1, addr 0x15 also is not
enabled as there is no driver for it.

Signed-off-by: Hans de Goede 
---
  arch/arm/boot/dts/Makefile |   1 +
  .../boot/dts/sun5i-a13-empire-electronix-d709.dts  | 241 +


The contents seem the same as sun5i-q8-common.dtsi and sun5i-a13-q8-tablet.dts.
Any chance you could use those instead?


Given the special needs of the touchscreen I do not think that that is a good 
idea.


On the side, any thoughts on how to handle the differences between various "Q8"
tablets, like different I2C-based sensors and WiFi chips?


For i2c based sensors the plan is to use devicetree overlays + an in kernel
overlay manager which probes the i2c bus (checking known touchscreen / 
accelerometer
addresses) and then picks the right touchscreen + accelerometer overlays.

Wifi is somewhat more tricky I must admit, esp. since there seem to be q8 a23 
based
tablet variants with usb wifi and others with sdio wifi. Since both busses are
discoverable I'm tempted to just enable both in devicetree, and let the kernel 
probe
and see what is actually there. This assume that the way the wifichip is powered
is the same on all boards, or at least that it is safe to enable the necessary
regulators on all boards ...


I'm asking because with Maxime's couple-regulator we should be able to get the
RTL8723BS on the Q8 A23/33 v1.5 working.


So this means enabled the sdio controller (should be safe on all boards?) and
enabling 2 regulators to power the wifi-chip. I think it will be safe to do this
even on boards where those regulators are not used, what do you think ?

Regards,

Hans
--
To unsubscribe from this list: send the line "unsubscribe devicetree" in
the body of a message to majord...@vger.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html

Re: [linux-sunxi] Re: [PATCH 4/5] ARM: dts: sun5i: Add dts file for the Empire Electronix D709 tablet

2015-12-21 Thread Chen-Yu Tsai 
On Tue, Dec 22, 2015 at 3:36 AM, Hans de Goede  wrote:
> Hi,
>
> On 21-12-15 17:11, Maxime Ripard wrote:
>>
>> Hi,x
>>
>> On Mon, Dec 21, 2015 at 11:46:18AM +0100, Hans de Goede wrote:

 On the side, any thoughts on how to handle the differences between
 various "Q8"
 tablets, like different I2C-based sensors and WiFi chips?
>>>
>>>
>>> For i2c based sensors the plan is to use devicetree overlays + an in
>>> kernel
>>> overlay manager which probes the i2c bus (checking known touchscreen /
>>> accelerometer
>>> addresses) and then picks the right touchscreen + accelerometer overlays.
>>>
>>> Wifi is somewhat more tricky I must admit, esp. since there seem to be q8
>>> a23 based
>>> tablet variants with usb wifi and others with sdio wifi. Since both
>>> busses are
>>> discoverable I'm tempted to just enable both in devicetree, and let the
>>> kernel probe
>>> and see what is actually there. This assume that the way the wifichip is
>>> powered
>>> is the same on all boards, or at least that it is safe to enable the
>>> necessary
>>> regulators on all boards ...
>>>
 I'm asking because with Maxime's couple-regulator we should be able to
 get the
 RTL8723BS on the Q8 A23/33 v1.5 working.
>>>
>>>
>>> So this means enabled the sdio controller (should be safe on all boards?)
>>> and
>>> enabling 2 regulators to power the wifi-chip. I think it will be safe to
>>> do this
>>> even on boards where those regulators are not used, what do you think ?
>>
>>
>> Wouldn't that introduce some useless power drain on those boards?
>
>
> If nothing is attached to those regulators (which I expect to be the case
> when
> they are not used to power wifi) then I would expect the drain to be
> minimal,
> my biggest worry is some board having tied these to ground, but I don't
> think
> that is very likely.

AFAIK the AXP datasheets mention that unused DCDC outputs should be left
floating. Not sure if this applies to LDO outputs as well. But any used
outputs would have a bypass capacitor.

>From the board designs I've seen, this seems to be the common case.
I'm not an electrical engineer, but I think we're covered here.

Another thing we need to deal with is the different power sequencing
requirements for the different SDIO chips.

Regards
ChenYu
--
To unsubscribe from this list: send the line "unsubscribe devicetree" in
the body of a message to majord...@vger.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html

Re: [linux-sunxi] Re: [PATCH 4/5] ARM: dts: sun5i: Add dts file for the Empire Electronix D709 tablet

2015-12-21 Thread Maxime Ripard 
Hi,x

On Mon, Dec 21, 2015 at 11:46:18AM +0100, Hans de Goede wrote:
> >On the side, any thoughts on how to handle the differences between various 
> >"Q8"
> >tablets, like different I2C-based sensors and WiFi chips?
> 
> For i2c based sensors the plan is to use devicetree overlays + an in kernel
> overlay manager which probes the i2c bus (checking known touchscreen / 
> accelerometer
> addresses) and then picks the right touchscreen + accelerometer overlays.
> 
> Wifi is somewhat more tricky I must admit, esp. since there seem to be q8 a23 
> based
> tablet variants with usb wifi and others with sdio wifi. Since both busses are
> discoverable I'm tempted to just enable both in devicetree, and let the 
> kernel probe
> and see what is actually there. This assume that the way the wifichip is 
> powered
> is the same on all boards, or at least that it is safe to enable the necessary
> regulators on all boards ...
> 
> >I'm asking because with Maxime's couple-regulator we should be able to get 
> >the
> >RTL8723BS on the Q8 A23/33 v1.5 working.
> 
> So this means enabled the sdio controller (should be safe on all boards?) and
> enabling 2 regulators to power the wifi-chip. I think it will be safe to do 
> this
> even on boards where those regulators are not used, what do you think ?

Wouldn't that introduce some useless power drain on those boards?

Thanks!
Maxime

-- 
Maxime Ripard, Free Electrons
Embedded Linux, Kernel and Android engineering
http://free-electrons.com


signature.asc
Description: Digital signature