linux-kernel - Re: [PATCH 6/6] i3c: master: svc: fix random hot join failure since timeout error

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Message-ID: <20231017163335.16770af2@xps-13>
Date:   Tue, 17 Oct 2023 16:33:35 +0200
From:   Miquel Raynal <miquel.raynal@...tlin.com>
To:     Frank Li <Frank.Li@....com>
Cc:     conor.culhane@...vaco.com, alexandre.belloni@...tlin.com,
        joe@...ches.com, linux-i3c@...ts.infradead.org,
        linux-kernel@...r.kernel.org, imx@...ts.linux.dev
Subject: Re: [PATCH 6/6] i3c: master: svc: fix random hot join failure since
 timeout error

Hi Frank,

Frank.Li@....com wrote on Mon, 16 Oct 2023 11:32:32 -0400:

> master side report:
>   silvaco-i3c-master 44330000.i3c-master: Error condition: MSTATUS 0x020090c7, MERRWARN 0x00100000
> 
> BIT 20: TIMEOUT error
>   The module has stalled too long in a frame. This happens when:
>   - The TX FIFO or RX FIFO is not handled and the bus is stuck in the
> middle of a message,
>   - No STOP was issued and between messages,
>   - IBI manual is used and no decision was made.
>   The maximum stall period is 10 KHz or 100 μs.
> 
> This is a just warning. System irq thread schedule latency is possible

							can be bigger
> bigger than 100us. Just omit this waring.

I'm not sure this is the correct approach. It's a real issue but there
is not much we can do about it. Perhaps dev_err is too high, but I
would not entirely drop this message. Maybe a comment and turning the
message into a dbg printk would be more appropriate?

> Fixes: dd3c52846d59 ("i3c: master: svc: Add Silvaco I3C master driver")
> Cc: stable@...r.kernel.org
> Signed-off-by: Frank Li <Frank.Li@....com>
> ---
>  drivers/i3c/master/svc-i3c-master.c | 6 ++++++
>  1 file changed, 6 insertions(+)
> 
> diff --git a/drivers/i3c/master/svc-i3c-master.c b/drivers/i3c/master/svc-i3c-master.c
> index 5bca369d6912..18bc277edc8a 100644
> --- a/drivers/i3c/master/svc-i3c-master.c
> +++ b/drivers/i3c/master/svc-i3c-master.c
> @@ -93,6 +93,7 @@
>  #define SVC_I3C_MINTMASKED   0x098
>  #define SVC_I3C_MERRWARN     0x09C
>  #define   SVC_I3C_MERRWARN_NACK BIT(2)
> +#define   SVC_I3C_MERRWARN_TIMEOUT BIT(20)
>  #define SVC_I3C_MDMACTRL     0x0A0
>  #define SVC_I3C_MDATACTRL    0x0AC
>  #define   SVC_I3C_MDATACTRL_FLUSHTB BIT(0)
> @@ -225,6 +226,11 @@ static bool svc_i3c_master_error(struct svc_i3c_master *master)
>  	if (SVC_I3C_MSTATUS_ERRWARN(mstatus)) {
>  		merrwarn = readl(master->regs + SVC_I3C_MERRWARN);
>  		writel(merrwarn, master->regs + SVC_I3C_MERRWARN);
> +
> +		/* ignore timeout error */
> +		if (merrwarn & SVC_I3C_MERRWARN_TIMEOUT)
> +			return false;
> +
>  		dev_err(master->dev,
>  			"Error condition: MSTATUS 0x%08x, MERRWARN 0x%08x\n",
>  			mstatus, merrwarn);


Thanks,
Miquèl