Re: [PATCH v2 3/3] i3c: master: svc: fix invalidate IBI type and miss call client IBI handler

From: Miquel Raynal
Date: Tue May 07 2024 - 04:04:45 EST


Hi Frank,

Frank.Li@xxxxxxx wrote on Mon, 6 May 2024 12:40:09 -0400:

> In an In-Band Interrupt (IBI) handle, the code logic is as follows:
>
> 1: writel(SVC_I3C_MCTRL_REQUEST_AUTO_IBI | SVC_I3C_MCTRL_IBIRESP_AUTO,
> master->regs + SVC_I3C_MCTRL);
>
> 2: ret = readl_relaxed_poll_timeout(master->regs + SVC_I3C_MSTATUS, val,
> SVC_I3C_MSTATUS_IBIWON(val), 0, 1000);
> ...
> 3: ibitype = SVC_I3C_MSTATUS_IBITYPE(status);
> ibiaddr = SVC_I3C_MSTATUS_IBIADDR(status);
>
> SVC_I3C_MSTATUS_IBIWON may be set before step 1. Thus, step 2 will return
> immediately, and the I3C controller has not sent out the 9th SCL yet.
> Consequently, ibitype and ibiaddr are 0, resulting in an unknown IBI type
> occurrence and missing call I3C client driver's IBI handler.
>
> A typical case is that SVC_I3C_MSTATUS_IBIWON is set when an IBI occurs
> during the controller send start frame in svc_i3c_master_xfer().
>
> Clear SVC_I3C_MSTATUS_IBIWON before issue SVC_I3C_MCTRL_REQUEST_AUTO_IBI
> to fix this issue.
>
> Cc: stable@xxxxxxxxxxxxxxx
> Fixes: 5e5e3c92e748 ("i3c: master: svc: fix wrong data return when IBI happen during start frame")
> Signed-off-by: Frank Li <Frank.Li@xxxxxxx>
> ---
>
> Notes:
> Change from v1 to v2
> - improve comments.
>
> drivers/i3c/master/svc-i3c-master.c | 16 +++++++++++++---
> 1 file changed, 13 insertions(+), 3 deletions(-)
>
> diff --git a/drivers/i3c/master/svc-i3c-master.c b/drivers/i3c/master/svc-i3c-master.c
> index 94e4954509558..032fe032ec433 100644
> --- a/drivers/i3c/master/svc-i3c-master.c
> +++ b/drivers/i3c/master/svc-i3c-master.c
> @@ -415,6 +415,19 @@ static void svc_i3c_master_ibi_work(struct work_struct *work)
> int ret;
>
> mutex_lock(&master->lock);
> + /*
> + * IBIWON may be set before SVC_I3C_MCTRL_REQUEST_AUTO_IBI, causing
> + * readl_relaxed_poll_timeout() to return immediately. Consequently,
> + * ibitype will be 0 since it was last updated only after the 8th SCL
> + * cycle, leading to missed client IBI handlers.
> + *
> + * A typical scenario is when IBIWON occurs and bus arbitration is lost
> + * at svc_i3c_master_priv_xfers().
> + *
> + * Clear SVC_I3C_MINT_IBIWON before sending SVC_I3C_MCTRL_REQUEST_AUTO_IBI.
> + */

Thanks a lot.

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

Thanks,
Miquèl