linux-kernel - Re: [PATCH] i3c: master: svc: adjust the first broadcast speed

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Message-ID: <ZpkhwIoyMj37EZIT@lizhi-Precision-Tower-5810>
Date: Thu, 18 Jul 2024 10:08:00 -0400
From: Frank Li <Frank.li@....com>
To: carlos.song@....com
Cc: miquel.raynal@...tlin.com, conor.culhane@...vaco.com,
	alexandre.belloni@...tlin.com, linux-i3c@...ts.infradead.org,
	linux-kernel@...r.kernel.org, linux-imx@....com
Subject: Re: [PATCH] i3c: master: svc: adjust the first broadcast speed

On Thu, Jul 18, 2024 at 05:13:29PM +0800, carlos.song@....com wrote:
> From: Carlos Song <carlos.song@....com>
> 
> According to the i3c spec 6.2 Timing Specification, the first
> broadcast open drain timing should be adjust to High Period
> of SCL Clock is 200ns at least. I3C device working as a i2c
> device will see the broadcast to close its Spike Filter to
> change to i3c mode. After that I3C open drain SCL high level
> should be adjust to 32ns~45ns.
> 
> Signed-off-by: Carlos Song <carlos.song@....com>


If you sent two patch together, it should use "git format -n2", need
1/2, 2/2 in subject.

If create patch seperately, send patch one by one to avoid combine into
one email thread.

> ---
>  drivers/i3c/master/svc-i3c-master.c | 47 +++++++++++++++++++++++++++++
>  1 file changed, 47 insertions(+)
> 
> diff --git a/drivers/i3c/master/svc-i3c-master.c b/drivers/i3c/master/svc-i3c-master.c
> index 78116530f431..2d68c8d34089 100644
> --- a/drivers/i3c/master/svc-i3c-master.c
> +++ b/drivers/i3c/master/svc-i3c-master.c
> @@ -142,6 +142,7 @@ struct svc_i3c_cmd {
>  	unsigned int actual_len;
>  	struct i3c_priv_xfer *xfer;
>  	bool continued;
> +	bool slow_address;
>  };
>  
>  struct svc_i3c_xfer {
> @@ -214,6 +215,10 @@ struct svc_i3c_master {
>  	} ibi;
>  	struct mutex lock;
>  	int enabled_events;
> +
> +	unsigned long fclk_rate;
> +	u32 mctrl_config;
> +	bool first_broadcast;

	slow_speed may be better?
>  };
>  
>  /**
> @@ -531,6 +536,36 @@ static irqreturn_t svc_i3c_master_irq_handler(int irq, void *dev_id)
>  	return IRQ_HANDLED;
>  }
>  
> +static void svc_i3c_master_set_slow_address_speed(struct svc_i3c_master *master)
> +{
> +	struct i3c_bus *bus = i3c_master_get_bus(&master->base);
> +	u32 ppbaud, odbaud, odhpp, mconfig;
> +
> +	master->mctrl_config = readl(master->regs + SVC_I3C_MCONFIG);
> +	mconfig = master->mctrl_config;
> +
> +	/*
> +	 * Set the I3C OPEN-DRAIN mode to the FM speed of 50% duty-cycle(400K/2500ns),
> +	 * so that the first broadcast is visible to all devices on the i3c bus.
> +	 * I3C device with 50ns filter will turn off the filter.
> +	 */
> +
> +	ppbaud = FIELD_GET(GENMASK(11, 8), mconfig);
> +	odhpp = 0;
> +	odbaud = DIV_ROUND_UP(master->fclk_rate, bus->scl_rate.i2c * (2 + 2 * ppbaud)) - 1;
> +	mconfig &= ~GENMASK(24, 16);
> +	mconfig |= SVC_I3C_MCONFIG_ODBAUD(odbaud) | SVC_I3C_MCONFIG_ODHPP(odhpp);
> +
> +	writel(mconfig, master->regs + SVC_I3C_MCONFIG);

	master->slow_speed = true;
> +}
> +
> +static void svc_i3c_master_set_default_speed(struct svc_i3c_master *master)
> +{
	if (master->slow_speed)
		writel()
		master->slow_speed = false
	}
	
to avoid set default speed every time.

> +	/* Whatever, setting the controller to initial configuration */
> +	writel(master->mctrl_config, master->regs + SVC_I3C_MCONFIG);
> +	master->first_broadcast = false;
> +}
> +
>  static int svc_i3c_master_bus_init(struct i3c_master_controller *m)
>  {
>  	struct svc_i3c_master *master = to_svc_i3c_master(m);
> @@ -624,6 +659,8 @@ static int svc_i3c_master_bus_init(struct i3c_master_controller *m)
>  	      SVC_I3C_MCONFIG_I2CBAUD(i2cbaud);
>  	writel(reg, master->regs + SVC_I3C_MCONFIG);
>  
> +	master->first_broadcast = true;
> +	master->fclk_rate = fclk_rate;
>  	/* Master core's registration */
>  	ret = i3c_master_get_free_addr(m, 0);
>  	if (ret < 0)
> @@ -1250,6 +1287,8 @@ static void svc_i3c_master_start_xfer_locked(struct svc_i3c_master *master)
>  
>  	for (i = 0; i < xfer->ncmds; i++) {
>  		struct svc_i3c_cmd *cmd = &xfer->cmds[i];
> +		if (cmd->slow_address)
> +			svc_i3c_master_set_slow_address_speed(master);


		if (cmd->slow_address)
			svc_i3c_master_set_slow_address_speed(master);
		else
			svc_i3c_master_set_default_speed(master);

will be easy understand

>  
>  		ret = svc_i3c_master_xfer(master, cmd->rnw, xfer->type,
>  					  cmd->addr, cmd->in, cmd->out,
> @@ -1259,6 +1298,9 @@ static void svc_i3c_master_start_xfer_locked(struct svc_i3c_master *master)
>  		if (cmd->xfer)
>  			cmd->xfer->actual_len = cmd->actual_len;
>  
> +		if (cmd->slow_address)
> +			svc_i3c_master_set_default_speed(master);
> +
>  		if (ret)
>  			break;
>  	}
> @@ -1346,6 +1388,11 @@ static int svc_i3c_master_send_bdcast_ccc_cmd(struct svc_i3c_master *master,
>  	cmd->actual_len = 0;
>  	cmd->continued = false;
>  
> +	if (master->first_broadcast)
> +		cmd->slow_address = true;
> +	else
> +		cmd->slow_address = false;
> +
>  	mutex_lock(&master->lock);
>  	svc_i3c_master_enqueue_xfer(master, xfer);
>  	if (!wait_for_completion_timeout(&xfer->comp, msecs_to_jiffies(1000)))
> -- 
> 2.34.1
>