linux-kernel - Re: [PATCH v8 3/4] i2c: i801: add support of Host Notify

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Message-ID: <20160615081247.GQ24234@mail.corp.redhat.com>
Date:	Wed, 15 Jun 2016 10:12:47 +0200
From:	Benjamin Tissoires <benjamin.tissoires@...hat.com>
To:	Wolfram Sang <wsa@...-dreams.de>, Jonathan Corbet <corbet@....net>,
	Corey Minyard <minyard@....org>,
	Jean Delvare <jdelvare@...e.de>,
	Guenter Roeck <linux@...ck-us.net>,
	Dmitry Torokhov <dmitry.torokhov@...il.com>,
	Andrew Duggan <aduggan@...aptics.com>,
	Christopher Heiny <cheiny@...aptics.com>
Cc:	linux-i2c@...r.kernel.org, linux-doc@...r.kernel.org,
	linux-kernel@...r.kernel.org, linux-input@...r.kernel.org
Subject: Re: [PATCH v8 3/4] i2c: i801: add support of Host Notify

On Jun 09 2016 or thereabouts, Benjamin Tissoires wrote:
> The i801 chip can handle the Host Notify feature since ICH 3 as mentioned
> in http://www.intel.com/content/dam/doc/datasheet/82801ca-io-controller-hub-3-datasheet.pdf
> 
> Enable the functionality unconditionally and propagate the alert
> on each notification.
> 
> With a T440s and a Synaptics touchpad that implements Host Notify, the
> payload data is always 0x0000, so I am not sure if the device actually
> sends the payload or if there is a problem regarding the implementation.
> 
> Tested-by: Andrew Duggan <aduggan@...aptics.com>
> Acked-by: Wolfram Sang <wsa@...-dreams.de>
> Signed-off-by: Benjamin Tissoires <benjamin.tissoires@...hat.com>
> ---
> changes in v2:
> - removed the description of the Slave functionality support in the chip table
>   (the table shows what is supported, not what the hardware is capable of)
> - use i2c-smbus to forward the notification
> - remove the fifo, and directly retrieve the address and payload in the worker
> - do not check for Host Notification is the feature is not enabled
> - use inw_p() to read the payload instead of 2 inb_p() calls
> - add /* fall-through */ comment
> - unconditionally enable Host Notify if the hardware supports it (can be
>   disabled by the user)
>  
> no changes in v3
> 
> changes in v4:
> - make use of the new API -> no more worker spawning here
> - solved a race between the access of the Host Notify registers and the actual
>   I2C transfers.
> 
> changes in v5:
> - added SKL Host Notify support
> 
> changes in v6:
> - select I2C_SMBUS in Kconfig to prevent an undefined reference when I2C_I801
>   is set to 'Y' while I2C_SMBUS is set to 'M'
> 
> no changes in v7
> 
> changes in v8:
> - reapplied after http://patchwork.ozlabs.org/patch/632768/ and merged the
>   conflict (minor conflict in the struct i801_priv).
> - removed the .resume hook as upstream changed suspend/resume hooks and there
>   is no need in the end to re-enable host notify on resume (tested on Lenovo
>   t440 and t450).

Actually, this hook seemed to be required on the Lenovo T440 (Haswell)
but not on the T450 (Broadwell) laptop I have now here.

Wolfram, I can resend the whole series or a follow-up patch to re-enable
after resume Host Notify. How do you prefer I deal with that?

Cheers,
Benjamin