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Message-ID:
<VI1PR04MB500513D0A8E03D49EA2558ECE88F2@VI1PR04MB5005.eurprd04.prod.outlook.com>
Date: Thu, 22 Aug 2024 03:04:42 +0000
From: Carlos Song <carlos.song@....com>
To: Miquel Raynal <miquel.raynal@...tlin.com>
CC: "alexandre.belloni@...tlin.com" <alexandre.belloni@...tlin.com>, Frank Li
<frank.li@....com>, "conor.culhane@...vaco.com" <conor.culhane@...vaco.com>,
"linux-i3c@...ts.infradead.org" <linux-i3c@...ts.infradead.org>,
"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
"imx@...ts.linux.dev" <imx@...ts.linux.dev>, dl-linux-imx <linux-imx@....com>
Subject: RE: [EXT] Re: [PATCH v2 1/2] i3c: master: support to adjust first
broadcast address speed
> -----Original Message-----
> From: Miquel Raynal <miquel.raynal@...tlin.com>
> Sent: Thursday, August 22, 2024 12:07 AM
> To: Carlos Song <carlos.song@....com>
> Cc: alexandre.belloni@...tlin.com; Frank Li <frank.li@....com>;
> conor.culhane@...vaco.com; linux-i3c@...ts.infradead.org;
> linux-kernel@...r.kernel.org; imx@...ts.linux.dev; dl-linux-imx
> <linux-imx@....com>
> Subject: [EXT] Re: [PATCH v2 1/2] i3c: master: support to adjust first broadcast
> address speed
>
> Caution: This is an external email. Please take care when clicking links or
> opening attachments. When in doubt, report the message using the 'Report
> this email' button
>
>
> Hi carlos.song@....com,
>
> carlos.song@....com wrote on Wed, 7 Aug 2024 14:13:05 +0800:
>
> > From: Carlos Song <carlos.song@....com>
> >
> > According to I3C spec 6.2 Timing Specification, the Open Drain High
> > Period of SCL Clock timing for first broadcast address should be
> > adjusted to 200ns at least. I3C device working as i2c device will see
> > the broadcast to close its Spike Filter then change to work at I3C
> > mode. After that I3C open drain SCL high level should be adjusted back.
> >
> > Signed-off-by: Carlos Song <carlos.song@....com>
> > Reviewed-by: Frank Li <Frank.Li@....com>
> > ---
> > - Fix set_speed description from Frank's comment
> > ---
> > drivers/i3c/master.c | 12 ++++++++++++
> > include/linux/i3c/master.h | 18 ++++++++++++++++++
> > 2 files changed, 30 insertions(+)
> >
> > diff --git a/drivers/i3c/master.c b/drivers/i3c/master.c index
> > 7028f03c2c42..6f3eb710a75d 100644
> > --- a/drivers/i3c/master.c
> > +++ b/drivers/i3c/master.c
> > @@ -1868,6 +1868,12 @@ static int i3c_master_bus_init(struct
> i3c_master_controller *master)
> > goto err_bus_cleanup;
> > }
> >
> > + if (master->ops->set_speed) {
> > + ret = master->ops->set_speed(master,
> I3C_OPEN_DRAIN_SLOW_SPEED);
> > + if (ret)
> > + goto err_bus_cleanup;
> > + }
> > +
> > /*
> > * Reset all dynamic address that may have been assigned before
> > * (assigned by the bootloader for example).
> > @@ -1876,6 +1882,12 @@ static int i3c_master_bus_init(struct
> i3c_master_controller *master)
> > if (ret && ret != I3C_ERROR_M2)
> > goto err_bus_cleanup;
> >
> > + if (master->ops->set_speed) {
> > + master->ops->set_speed(master,
> I3C_OPEN_DRAIN_NORMAL_SPEED);
> > + if (ret)
> > + goto err_bus_cleanup;
> > + }
> > +
> > /* Disable all slave events before starting DAA. */
> > ret = i3c_master_disec_locked(master, I3C_BROADCAST_ADDR,
> > I3C_CCC_EVENT_SIR |
> > I3C_CCC_EVENT_MR | diff --git a/include/linux/i3c/master.h
> > b/include/linux/i3c/master.h index 074f632868d9..b8daf09a9a4a 100644
> > --- a/include/linux/i3c/master.h
> > +++ b/include/linux/i3c/master.h
> > @@ -277,6 +277,20 @@ enum i3c_bus_mode {
> > I3C_BUS_MODE_MIXED_SLOW,
> > };
> >
> > +/**
> > + * enum i3c_open_drain_speed - I3C open drain speed
> > + * @I3C_OPEN_DRAIN_SLOW_SPEED: Slow open drain speed for First
> Broadcast Address.
>
> A few minor style comments:
>
> open-drain
>
> ...for sending the first broadcast address.
>
> > + * First Broadcast Address in this speed is
> visible to all I2C/I3C
>
> The first broadcast address at this speed will be visible to all
>
> > + * devices on the I3C bus. I3C device working
> as a I2C device will
>
> ... I3C devices working in I2C mode will
>
> > + * turn off its 50ns Spike Filter to change to
> work in I3C mode.
>
> their spike filter when
> switching into I3C mode.
>
> > + * @I3C_OPEN_DRAIN_NORMAL_SPEED: Normal open drain speed
> configured
> > + according to
>
> open-drain
>
> > + * I3C bus mode.
>
> I'm sorry, can you rephrase "configured according to I3C bus mode" ?
>
Hi! Thank you for your ack! I will change above to:
/**
* enum i3c_open_drain_speed - I3C open-drain speed
* @I3C_OPEN_DRAIN_SLOW_SPEED: Slow open-drain speed for sending the first
* broadcast address. The first broadcast address at this speed
* will be visible to all devices on the I3C bus. I3C devices
* working in I2C mode will turn off their spike filter when
* switching into I3C mode.
* @I3C_OPEN_DRAIN_NORMAL_SPEED: Normal open-drain speed in I3C bus mode.
*/
Is this acceptable?
> > + */
> > +enum i3c_open_drain_speed {
> > + I3C_OPEN_DRAIN_SLOW_SPEED,
> > + I3C_OPEN_DRAIN_NORMAL_SPEED,
> > +};
> > +
> > /**
> > * enum i3c_addr_slot_status - I3C address slot status
> > * @I3C_ADDR_SLOT_FREE: address is free @@ -436,6 +450,9 @@ struct
> > i3c_bus {
> > * NULL.
> > * @enable_hotjoin: enable hot join event detect.
> > * @disable_hotjoin: disable hot join event detect.
> > + * @set_speed: adjust I3C bus speed, which is generally used for reducing
> the speed
> > + * for first broardcast address.
> > + *
> > */
> > struct i3c_master_controller_ops {
> > int (*bus_init)(struct i3c_master_controller *master); @@ -464,6
> > +481,7 @@ struct i3c_master_controller_ops {
> > struct i3c_ibi_slot *slot);
> > int (*enable_hotjoin)(struct i3c_master_controller *master);
> > int (*disable_hotjoin)(struct i3c_master_controller *master);
> > + int (*set_speed)(struct i3c_master_controller *master, enum
> > + i3c_open_drain_speed speed);
> > };
> >
> > /**
>
> Otherwise lgtm.
>
> Thanks,
> Miquèl
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