Received-SPF: pass (google.com: best guess record for domain of linux-wireless-owner@vger.kernel.org designates 209.132.180.67 as permitted sender) client-ip=209.132.180.67;
Subject: Re: RTL8188ETV chip, r8188eu module and power management
To:     Anton Sviridenko <anton@picapica.im>,
        linux-wireless@vger.kernel.org
References: <20190717060609.GA21298@picapica.im>
From:   Larry Finger <Larry.Finger@lwfinger.net>
Message-ID: <f0680746-0a0a-b33e-b4ef-246b08949d99@lwfinger.net>
Date:   Thu, 18 Jul 2019 10:58:03 -0500
User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:60.0) Gecko/20100101
 Thunderbird/60.7.2
MIME-Version: 1.0
In-Reply-To: <20190717060609.GA21298@picapica.im>
Content-Type: text/plain; charset=utf-8; format=flowed
Content-Language: en-US
Content-Transfer-Encoding: 7bit
Sender: linux-wireless-owner@vger.kernel.org
Precedence: bulk

On 7/17/19 1:06 AM, Anton Sviridenko wrote:
> 
> Hello
> 
> we are using FN-8112MET PCB module having RTL8188ETV chip on it.
> Device is running customized Linux version based on Linux 4.19 release.
> Driver module "r8188eu" is not modified, taken from vanilla sources as
> is.
> Wi-Fi connection is used occasionally, and rest of the time it is
> preferable to have minimal power consumption.
> 
> Such situation is observed:
> 
> 1) Linux kernel is started, driver module is not loaded
> 2) module "r8188eu" is loaded manually with parameters "rtw_power_mgnt=2
> rtw_enusbss=1"
> 3) device starts consuming more current (+20mA)
> 3) after the module is unloaded, current consumption remains at the same
> level
> 
> We still have to double-check this, but looks like driver module does
> not leave the device in the same state on module unload.
> 
> Few questions:
> 1) Is "r8188eu" driver from the mainline kernel the best possible option
> available for this chip?
> 
> 2) Where can I look for some documentation about kernel module
> parameters related to power management and their meanings?
> Source code is not very descriptive, and I was not able to google
> anything better, looks like this chip specifications are not available in
> public.
> 
> 3) Is there some option to completely poweroff this chip using software
> and then bring it back when needed?

1. No. There is a newer driver for the RTL8188EU chips at 
http://github.com/lwfinger/rtl8188eu.git. The v5.2.2.4 branch has what I think 
is the best.

2. The source code is the only documentation available.

3. The page at 
https://unix.stackexchange.com/questions/165447/turning-off-power-to-usb-port-or-turn-off-power-to-entire-usb-subsystem 
has some info on disabling USB hubs that support per-port power switching.

Larry