linux-kernel - Re: [PATCH V5 1/2] i3c: master: support to adjust first broadcast address speed

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Message-ID: <ZuhNIpoTe61M7rEL@lizhi-Precision-Tower-5810>
Date: Mon, 16 Sep 2024 11:22:10 -0400
From: Frank Li <Frank.li@....com>
To: carlos.song@....com, alexandre.belloni@...tlin.com
Cc: miquel.raynal@...tlin.com, conor.culhane@...vaco.com,
	linux-i3c@...ts.infradead.org, linux-kernel@...r.kernel.org,
	imx@...ts.linux.dev
Subject: Re: [PATCH V5 1/2] i3c: master: support to adjust first broadcast
 address speed

On Mon, Sep 16, 2024 at 11:13:08AM -0400, Frank Li wrote:
> On Tue, Sep 10, 2024 at 01:16:25PM +0800, carlos.song@....com wrote:
> > 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: Miquel Raynal <miquel.raynal@...tlin.com>
> > Reviewed-by: Frank Li <Frank.Li@....com>
> > ---
>
> Alex:
> 	I saw v6.11 tag, These two patches is critical for imx93-9x9-evk
> boards. without these two patch, all i3c devices can't be proble. I am
> sure if there still have chance to get merged for 6.12.

Sorry, miss 'not'
'I am not sure if there still have chance to get merged for 6.12.'

>
> Frank
>
>
> > Change for V5:
> > - No change. Resend this patch to list after subscribe to mail list.
> > Change for V4:
> > - No change. Send this patch with svc-i3c-master.c fix patch.
> > Change for V3:
> > - Modify comments from Miquel's suggestion
> > Change for V2:
> > - Fix set_speed description from Frank's comment
> > ---
> >  drivers/i3c/master.c       | 12 ++++++++++++
> >  include/linux/i3c/master.h | 16 ++++++++++++++++
> >  2 files changed, 28 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..2a1ed05d5782 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 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.
> > + */
> > +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 +450,7 @@ struct i3c_bus {
> >   *		      NULL.
> >   * @enable_hotjoin: enable hot join event detect.
> >   * @disable_hotjoin: disable hot join event detect.
> > + * @set_speed: adjust I3C open drain mode timing.
> >   */
> >  struct i3c_master_controller_ops {
> >  	int (*bus_init)(struct i3c_master_controller *master);
> > @@ -464,6 +479,7 @@ 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);
> >  };
> >
> >  /**
> > --
> > 2.34.1
> >