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Message-ID:
<VI1PR04MB50058C9E30C4A357E43CB34FE8AD2@VI1PR04MB5005.eurprd04.prod.outlook.com>
Date: Fri, 19 Jul 2024 16:37:01 +0000
From: Carlos Song <carlos.song@....com>
To: Frank Li <frank.li@....com>
CC: "miquel.raynal@...tlin.com" <miquel.raynal@...tlin.com>,
"conor.culhane@...vaco.com" <conor.culhane@...vaco.com>,
"alexandre.belloni@...tlin.com" <alexandre.belloni@...tlin.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: [PATCH v2] i3c: master: svc: adjust the first broadcast speed
> -----Original Message-----
> From: Frank Li <frank.li@....com>
> Sent: Friday, July 19, 2024 11:01 PM
> To: Carlos Song <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; imx@...ts.linux.dev; dl-linux-imx
> <linux-imx@....com>
> Subject: Re: [PATCH v2] i3c: master: svc: adjust the first broadcast speed
>
> On Fri, Jul 19, 2024 at 04:03:51PM +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>
> > ---
> > Change for V2:
> > - use slow_speed instead of first_broadcast
> > - add default_speed variable in svc_i3c_xfer to avoid set default
> > speed every time
> > - change start_xfer if else for easy understand
> > ---
> > drivers/i3c/master/svc-i3c-master.c | 55
> > +++++++++++++++++++++++++++++
> > 1 file changed, 55 insertions(+)
> >
> > diff --git a/drivers/i3c/master/svc-i3c-master.c
> > b/drivers/i3c/master/svc-i3c-master.c
> > index 78116530f431..7cd3a9a4d7dd 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 +215,11 @@ struct svc_i3c_master {
> > } ibi;
> > struct mutex lock;
> > int enabled_events;
> > +
> > + unsigned long fclk_rate;
> > + u32 mctrl_config;
> > + bool slow_speed;
> > + bool default_speed;
>
> I think you needn't two varible 'slow_speed' and 'default_speed'.
> default_speed should always !slow_speed
>
> Frank
>
Hi, Frank
In fact, I am struggling for using just one variable: slow speed. Adding a variable "default_speed "was also a have-to move.
If I use "if else" in xfer for easy understand, it means I only can change the MCTRL register value one time in every xfer. So in the first xfer, I must change slow_speed to false, then next xfer cmd->slow_address will be false. So in next xfer, I can set initial configuration back to the controller.
But the question is I have to set it every time, so I add the extra variable to avoid writel in every xfer.
It looks bad... Sorry for my poor coding.
If only one variable " slow_speed " is used , I think "if else" and "writel one time", only one can be used. Maybe there is a better code method but I don't get it?
Carlos
> > };
> >
> > /**
> > @@ -531,6 +537,43 @@ 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 = false;
> > +}
> > +
> > +static void svc_i3c_master_set_default_speed(struct svc_i3c_master
> > +*master) {
> > + /*
> > + * The bus mode is already determined when the bus is initialized, so
> setting initial
> > + * configuration back to the controller. No need to set it in every transfer,
> just
> > + * restore it once time.
> > + */
> > + if (!master->default_speed) {
> > + writel(master->mctrl_config, master->regs + SVC_I3C_MCONFIG);
> > + master->default_speed = true;
> > + }
> > +}
> > +
> > static int svc_i3c_master_bus_init(struct i3c_master_controller *m)
> > {
> > struct svc_i3c_master *master = to_svc_i3c_master(m); @@ -624,6
> > +667,8 @@ 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->slow_speed = true;
> > + master->fclk_rate = fclk_rate;
> > /* Master core's registration */
> > ret = i3c_master_get_free_addr(m, 0);
> > if (ret < 0)
> > @@ -1251,6 +1296,11 @@ 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);
> > + else
> > + svc_i3c_master_set_default_speed(master);
> > +
> > ret = svc_i3c_master_xfer(master, cmd->rnw, xfer->type,
> > cmd->addr, cmd->in, cmd->out,
> > cmd->len, &cmd->actual_len,
> > @@ -1346,6 +1396,11 @@ static int
> svc_i3c_master_send_bdcast_ccc_cmd(struct svc_i3c_master *master,
> > cmd->actual_len = 0;
> > cmd->continued = false;
> >
> > + if (master->slow_speed)
> > + 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
> >
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