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From:   Hsin-Yi Wang <hsinyi@chromium.org>
Date:   Fri, 23 Aug 2019 16:13:29 +0800
Message-ID: <CAJMQK-gb+A9dwyMqMcA5yaaXak9no8_=urwK0XbLnNAEGyZ_hg@mail.gmail.com>
Subject: Re: [PATCH v2] i2c: mediatek: disable zero-length transfers for mt8183
To:     Qii Wang <qii.wang@mediatek.com>
Cc:     Wolfram Sang <wsa@the-dreams.de>,
        Yingjoe Chen <yingjoe.chen@mediatek.com>,
        Matthias Brugger <matthias.bgg@gmail.com>,
        Nicolas Boichat <drinkcat@chromium.org>,
        Jun Gao <jun.gao@mediatek.com>,
        Thomas Gleixner <tglx@linutronix.de>,
        linux-i2c@vger.kernel.org,
        "moderated list:ARM/FREESCALE IMX / MXC ARM ARCHITECTURE" 
        <linux-arm-kernel@lists.infradead.org>,
        linux-mediatek@lists.infradead.org,
        lkml <linux-kernel@vger.kernel.org>,
        Alexandru M Stan <amstan@chromium.org>
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On Fri, Aug 23, 2019 at 4:09 PM Qii Wang <qii.wang@mediatek.com> wrote:

> >
> >  static u32 mtk_i2c_functionality(struct i2c_adapter *adap)
> >  {
> > -     return I2C_FUNC_I2C | I2C_FUNC_SMBUS_EMUL;
> > +     if (adap->quirks->flags & I2C_AQ_NO_ZERO_LEN)
> > +             return I2C_FUNC_I2C |
> > +                     (I2C_FUNC_SMBUS_EMUL & ~I2C_FUNC_SMBUS_QUICK);
> > +     else
> > +             return I2C_FUNC_I2C | I2C_FUNC_SMBUS_EMUL;
>
> It can be removed?
See previous discussion: https://patchwork.kernel.org/patch/10814391/#22484435
but not all SoC's quirks has I2C_AQ_NO_ZERO_LEN.