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From:   Kevin Herbert <kph@platinasystems.com>
Date:   Fri, 11 Dec 2020 09:57:19 -0800
Message-ID: <CABP=6zahhQSXwG2MzR+ry9h8MCRqjyS=ysdvF1UYuejZd-0RkQ@mail.gmail.com>
Subject: Re: [EXT] Re: [v10] i2c: imx: support slave mode for imx I2C driver
To:     Biwen Li <biwen.li@nxp.com>
Cc:     Wolfram Sang <wsa@the-dreams.de>,
        "Biwen Li (OSS)" <biwen.li@oss.nxp.com>,
        Leo Li <leoyang.li@nxp.com>,
        "linux@rempel-privat.de" <linux@rempel-privat.de>,
        "kernel@pengutronix.de" <kernel@pengutronix.de>,
        "shawnguo@kernel.org" <shawnguo@kernel.org>,
        "s.hauer@pengutronix.de" <s.hauer@pengutronix.de>,
        "festevam@gmail.com" <festevam@gmail.com>,
        Aisheng Dong <aisheng.dong@nxp.com>,
        Clark Wang <xiaoning.wang@nxp.com>,
        "o.rempel@pengutronix.de" <o.rempel@pengutronix.de>,
        "linux-i2c@vger.kernel.org" <linux-i2c@vger.kernel.org>,
        "linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
        Jiafei Pan <jiafei.pan@nxp.com>,
        Xiaobo Xie <xiaobo.xie@nxp.com>,
        "linux-arm-kernel@lists.infradead.org" 
        <linux-arm-kernel@lists.infradead.org>
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Thanks for the tip. I attempted to see if the register was implemented
on the i.mx6, and it doesn't appear to be. I'll reach out to my FAE. I
found the datasheet and the register definitely isn't documented
there.

I was thinking of a patch that would keep track of state, and
synthesize the I2C_SLAVE_STOP on the next interrupt if it was a new
transaction. Does this seem too hacky to you? What are your thoughts?

Thanks,
Kevin

Thanks,
Kevin


On Wed, Dec 9, 2020 at 6:16 PM Biwen Li <biwen.li@nxp.com> wrote:
>
> Hi Kevin,
>
>
>
> After enabling idle interrupts, the i2c register will generate an idle in=
terrupts(whatever read or write) when i2c bus enter idle status. Then get I=
2C_SLAVE_STOP event.
>
> But don=E2=80=99t have the IBIC register(Maybe it=E2=80=99s a hidden regi=
ster) in imx. You can query about the AE of imx about this.
>
> static void i2c_imx_enable_bus_idle(struct imx_i2c_struct *i2c_imx)
>
> {
>
>         if (is_vf610_i2c(i2c_imx)) {
>
>                 unsigned int temp;
>
>
>
>                 temp =3D imx_i2c_read_reg(i2c_imx, IMX_I2C_IBIC);
>
>                 temp |=3D IBIC_BIIE;
>
>                 imx_i2c_write_reg(temp, i2c_imx, IMX_I2C_IBIC);
>
>         }
>
> }
>
>
>
> Best Regards,
>
> Biwen Li
>
> From: Kevin Herbert <kph@platinasystems.com>
> Sent: 2020=E5=B9=B412=E6=9C=8810=E6=97=A5 1:18
> To: Wolfram Sang <wsa@the-dreams.de>; Kevin Herbert <kph@platinasystems.c=
om>; Biwen Li (OSS) <biwen.li@oss.nxp.com>; Leo Li <leoyang.li@nxp.com>; li=
nux@rempel-privat.de; kernel@pengutronix.de; shawnguo@kernel.org; s.hauer@p=
engutronix.de; festevam@gmail.com; Aisheng Dong <aisheng.dong@nxp.com>; Cla=
rk Wang <xiaoning.wang@nxp.com>; o.rempel@pengutronix.de; linux-i2c@vger.ke=
rnel.org; linux-kernel@vger.kernel.org; Jiafei Pan <jiafei.pan@nxp.com>; Xi=
aobo Xie <xiaobo.xie@nxp.com>; linux-arm-kernel@lists.infradead.org; Biwen =
Li <biwen.li@nxp.com>
> Subject: [EXT] Re: [v10] i2c: imx: support slave mode for imx I2C driver
>
>
>
> Caution: EXT Email
>
> Even on an operation like writing a byte, I get I2C_SLAVE_WRITE_REQUESTED=
 followed by I2C_SLAVE_WRITE_RECEIVED, but no I2C_SLAVE_STOP. If I do a I2C=
 write of multiple bytes, I get I2c_SLAVE_WRITE_REQUESTED followed by multi=
ple I2C_SLAVE_WRITE_RECEIVED.
>
>
>
> Kevin
>
>
>
> On Wed, Dec 9, 2020 at 9:10 AM Wolfram Sang <wsa@the-dreams.de> wrote:
>
> On Wed, Dec 09, 2020 at 09:03:50AM -0800, Kevin Herbert wrote:
> > What is the protocol for the I2C_SLAVE_STOP event? I am working on my o=
wn
> > backend, and I've only tried it with this i.mx driver, and I do not rec=
eive
> > I2C_SLAVE_STOP at the end of every I2C transaction. It was my expectati=
on
> > I'd receive this event at the end of every frame. In my testing, I've n=
ever
> > received this event at all.
> >
> > Where are the I2C registers on the i.mx documented? My board is an i.mx=
6sx.
>
> Hmm, from a glimpse, it looks the STOP event is only sent after a write
> and not after a read? Does this match your findings?