linux-kernel - Re: [PATCH 0/2] ARM: dts: Use MMC pwrseq instead regulators for IGEP WiFi init

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Date:	Thu, 3 Dec 2015 15:28:49 -0300
From:	Javier Martinez Canillas <javier@....samsung.com>
To:	Tony Lindgren <tony@...mide.com>
Cc:	linux-kernel@...r.kernel.org, devicetree@...r.kernel.org,
	linux-omap@...r.kernel.org, linux-arm-kernel@...ts.infradead.org,
	Enric Balletbo i Serra <eballetbo@...il.com>
Subject: Re: [PATCH 0/2] ARM: dts: Use MMC pwrseq instead regulators for IGEP
 WiFi init

Hello Tony,

On 12/03/2015 03:16 PM, Tony Lindgren wrote:
> * Javier Martinez Canillas <javier@....samsung.com> [151203 10:03]:
>> Hello,
>>
>> This series converts the IGEPv2 (IGEP0020) and IGEP COM Module (IGEP0030)
>> Device Tree to use the MMC power sequence provider to initialize the SDIO
>> WiFi chip instead of using fake fixed regulators to just toggle the Reset
>> and Power pins in the chip.
>>
>> The patches were tested on an DM3730 IGEPv2 board but the IGEP COM Module
>> is the same with regard to the SDIO WiFi so it should be safe to land too.
>>
>> The IGEPv2 Rev.F and the IGEP COM Module Rev.G DTS were not converted due
>> using a different WiFi chip (wlcore instead of libertas) than the one in
>> the board I've access to test so I preferred to leave those untouched.
> 
> Do you have some solution for the start-up latency issue?
>

No, I don't and that's one of the reasons why I didn't want to touch the
DTS that have the wlcore chip.

The omap3-igep0020-rev-f.dts and omap3-igep0030-rev-g.dts don't have a
startup-delay-us property in the regulator for the WLAN_EN pin as is
the case for the IGEPv5 DTS but I don't know if those DTS are just wrong.

The DTS for the igep0020 and igep0030 that have the libertas chip,
did have a startup-delay-us for the WIFI_PDN but using the GPIOs
for RESET_N_W and WIFI_PDN in the mmc-pwrseq-simple reset-gpios is
enough to make the SDIO chip reset, be enumerated and WiFi to work
correctly so I don't know if that is really needed or is just a bad
description in the DTS.

Since is working for the boards with the libertas chip, I preferred
to remove the DTS hack but left the boards with wlcore chip since
you said the startup-delay-us is needed there (but probably we should
add to the regulators in the boards that don't have it then).

> Regards,
> 
> Tony
> 

Best regards,
-- 
Javier Martinez Canillas
Open Source Group
Samsung Research America
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