linux-kernel - Re: [PATCH 4/4] i3c: master: svc: set ODSTOP to let I2C device see the STOP signal

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Date:   Fri, 16 Jul 2021 00:57:37 +0200
From:   Miquel Raynal <miquel.raynal@...tlin.com>
To:     Clark Wang <xiaoning.wang@....com>
Cc:     conor.culhane@...vaco.com, alexandre.belloni@...tlin.com,
        vitor.soares@...opsys.com, boris.brezillon@...tlin.com,
        linux-i3c@...ts.infradead.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH 4/4] i3c: master: svc: set ODSTOP to let I2C device see
 the STOP signal

Hi Clark,

Clark Wang <xiaoning.wang@....com> wrote on Thu, 15 Jul 2021 16:24:13
+0800:

> If using I2C/I3C mixed mode, need to set ODSTOP. Otherwise, the I2C
> devices cannot see the stop signal. It may cause message sending errors.

Reviewed-by: Miquel Raynal <miquel.raynal@...tlin.com>

> 
> Signed-off-by: Clark Wang <xiaoning.wang@....com>
> ---
>  drivers/i3c/master/svc-i3c-master.c | 7 +++++--
>  1 file changed, 5 insertions(+), 2 deletions(-)
> 
> diff --git a/drivers/i3c/master/svc-i3c-master.c b/drivers/i3c/master/svc-i3c-master.c
> index 892e57fec4b0..b05cc7f521e6 100644
> --- a/drivers/i3c/master/svc-i3c-master.c
> +++ b/drivers/i3c/master/svc-i3c-master.c
> @@ -449,7 +449,7 @@ static int svc_i3c_master_bus_init(struct i3c_master_controller *m)
>  	struct i3c_device_info info = {};
>  	unsigned long fclk_rate, fclk_period_ns;
>  	unsigned int high_period_ns, od_low_period_ns;
> -	u32 ppbaud, pplow, odhpp, odbaud, i2cbaud, reg;
> +	u32 ppbaud, pplow, odhpp, odbaud, odstop, i2cbaud, reg;
>  	int ret;
>  
>  	/* Timings derivation */
> @@ -479,6 +479,7 @@ static int svc_i3c_master_bus_init(struct i3c_master_controller *m)
>  	switch (bus->mode) {
>  	case I3C_BUS_MODE_PURE:
>  		i2cbaud = 0;
> +		odstop = 0;
>  		break;
>  	case I3C_BUS_MODE_MIXED_FAST:
>  	case I3C_BUS_MODE_MIXED_LIMITED:
> @@ -487,6 +488,7 @@ static int svc_i3c_master_bus_init(struct i3c_master_controller *m)
>  		 * between the high and low period does not really matter.
>  		 */
>  		i2cbaud = DIV_ROUND_UP(1000, od_low_period_ns) - 2;
> +		odstop = 1;
>  		break;
>  	case I3C_BUS_MODE_MIXED_SLOW:
>  		/*
> @@ -494,6 +496,7 @@ static int svc_i3c_master_bus_init(struct i3c_master_controller *m)
>  		 * constraints as the FM+ mode.
>  		 */
>  		i2cbaud = DIV_ROUND_UP(2500, od_low_period_ns) - 2;
> +		odstop = 1;
>  		break;
>  	default:
>  		return -EINVAL;
> @@ -502,7 +505,7 @@ static int svc_i3c_master_bus_init(struct i3c_master_controller *m)
>  	reg = SVC_I3C_MCONFIG_MASTER_EN |
>  	      SVC_I3C_MCONFIG_DISTO(0) |
>  	      SVC_I3C_MCONFIG_HKEEP(0) |
> -	      SVC_I3C_MCONFIG_ODSTOP(0) |
> +	      SVC_I3C_MCONFIG_ODSTOP(odstop) |
>  	      SVC_I3C_MCONFIG_PPBAUD(ppbaud) |
>  	      SVC_I3C_MCONFIG_PPLOW(pplow) |
>  	      SVC_I3C_MCONFIG_ODBAUD(odbaud) |




Thanks,
Miquèl