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Message-ID: <dd07edbd62c7600996c7e7291c8ab819b8799319.camel@inka.de>
Subject: Re: [PATCH v3 10/12] HID: ft260: wake up device from power saving
 mode
From:   Enrik Berkhan <Enrik.Berkhan@inka.de>
To:     Michael Zaidman <michael.zaidman@gmail.com>, jikos@kernel.org
Cc:     linux-kernel@vger.kernel.org, linux-input@vger.kernel.org,
        linux-i2c@vger.kernel.org, germain.hebert@ca.abb.com
Date:   Mon, 31 Oct 2022 18:12:51 +0100
In-Reply-To: <20221030203403.4637-11-michael.zaidman@gmail.com>
References: <20221030203403.4637-1-michael.zaidman@gmail.com>
         <20221030203403.4637-11-michael.zaidman@gmail.com>
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Hi Michael,

On Sun, 2022-10-30 at 22:34 +0200, Michael Zaidman wrote:
> The FT260 can enter a power saving mode after being idle for longer than
> 5 seconds.
> 
> When being woken up from power saving mode by an I2C write request, it
> looks like a possible NACK will not be correctly reported back. As a
> workaround, the driver will request an I2C status report before starting
> the next I2C transfer if the FT260 has been idle for longer than 4800ms.

Unfortunately, I have found issues with this patch as it is. When I
tested from an installation running in KVM, I saw missed NACKs again.

A possible fix seems to be to send the extra status request after the
output report triggering the write. See
https://github.com/MichaelZaidman/hid-ft260/pull/7.

Cheers,
Enrik