linux-kernel - RE: [PATCH 1/3] Input: elan_i2c - Do no operation for elan_smbus_set

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Date:   Wed, 22 Jul 2020 10:19:33 +0800
From:   "Dave.Wang" <dave.wang@....com.tw>
To:     "'Dmitry Torokhov'" <dmitry.torokhov@...il.com>
Cc:     <Linux-input@...r.kernel.org>, <Linux-kernel@...r.kernel.org>,
        <phoenix@....com.tw>, <josh.chen@....com.tw>,
        <jingle.wu@....com.tw>, <kai.heng.feng@...onical.com>
Subject: RE: [PATCH 1/3] Input: elan_i2c - Do no operation for elan_smbus_set_mode function

Dear Dmitry,

Are there devices that do not trigger errors?
=> Yes, there exist devices that would act normally. However, our team
cannot organize the rule to recognize which devices could trigger this
command without error. 
What I sure about is that some devices would get TP no function while
triggering this command. 
Besides, ABS mode had been set in P/S2 protocol, so there is no need to set
ABS mode again in SMBUS driver. 

How do we put SMbus devices into low power mode?
=> As far as I am concerned, core.c only set the mode into ABS mode or
ENABLE_CALIBRATE mode after updating firmware. 
I don't know what or when to set SMbus devices into low power mode.

Best regards,
Dave

-----Original Message-----
From: Dmitry Torokhov [mailto:dmitry.torokhov@...il.com] 
Sent: Wednesday, July 22, 2020 12:13 AM
To: Dave Wang <dave.wang@....com.tw>
Cc: Linux-input@...r.kernel.org; Linux-kernel@...r.kernel.org;
phoenix@....com.tw; josh.chen@....com.tw; jingle.wu@....com.tw;
kai.heng.feng@...onical.com
Subject: Re: [PATCH 1/3] Input: elan_i2c - Do no operation for
elan_smbus_set_mode function

Hi Dave,

On Mon, Dec 09, 2019 at 06:11:07AM -0500, Dave Wang wrote:
> Some touchpads might get error while triggerring the set_mode command 
> in SMBus interface. Do no operation for elan_smbus_set_mode function.

Are there devices that do not trigger errors? How do we put SMbus devices
into low power mode?

> 
> Signed-off-by: Dave Wang <dave.wang@....com.tw>
> ---
>  drivers/input/mouse/elan_i2c_smbus.c | 5 +----
>  1 file changed, 1 insertion(+), 4 deletions(-)
> 
> diff --git a/drivers/input/mouse/elan_i2c_smbus.c 
> b/drivers/input/mouse/elan_i2c_smbus.c
> index 8c3185d54c73..bcb9ec4a7a6b 100644
> --- a/drivers/input/mouse/elan_i2c_smbus.c
> +++ b/drivers/input/mouse/elan_i2c_smbus.c
> @@ -84,10 +84,7 @@ static int elan_smbus_initialize(struct i2c_client 
> *client)
>  
>  static int elan_smbus_set_mode(struct i2c_client *client, u8 mode)  {
> -	u8 cmd[4] = { 0x00, 0x07, 0x00, mode };
> -
> -	return i2c_smbus_write_block_data(client, ETP_SMBUS_IAP_CMD,
> -					  sizeof(cmd), cmd);
> +	return 0; /* A no-op */
>  }
>  
>  static int elan_smbus_sleep_control(struct i2c_client *client, bool 
> sleep)
> --
> 2.17.1
> 

Thanks.

--
Dmitry