Re: [PATCH 2/2] i3c: master: svc: fix invalidate IBI type and miss call client IBI handler

From: Miquel Raynal
Date: Mon May 06 2024 - 05:00:08 EST


Hi Frank,

Frank.Li@xxxxxxx wrote on Wed, 24 Apr 2024 15:00:30 -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>
> ---
> drivers/i3c/master/svc-i3c-master.c | 6 +++---
> 1 file changed, 3 insertions(+), 3 deletions(-)
>
> diff --git a/drivers/i3c/master/svc-i3c-master.c b/drivers/i3c/master/svc-i3c-master.c
> index a2298ab460a37..3bfe8e694f840 100644
> --- a/drivers/i3c/master/svc-i3c-master.c
> +++ b/drivers/i3c/master/svc-i3c-master.c
> @@ -415,6 +415,9 @@ static void svc_i3c_master_ibi_work(struct work_struct *work)
> int ret;
>
> mutex_lock(&master->lock);
> + /* Clear the interrupt status */

Could you improve the comment to explain why this is needed here?

Otherwise seems okay, but I don't have any strong feelings here.

> + writel(SVC_I3C_MINT_IBIWON, master->regs + SVC_I3C_MSTATUS);
> +
> /* Acknowledge the incoming interrupt with the AUTOIBI mechanism */
> writel(SVC_I3C_MCTRL_REQUEST_AUTO_IBI |
> SVC_I3C_MCTRL_IBIRESP_AUTO,
> @@ -429,9 +432,6 @@ static void svc_i3c_master_ibi_work(struct work_struct *work)
> goto reenable_ibis;
> }
>
> - /* Clear the interrupt status */
> - writel(SVC_I3C_MINT_IBIWON, master->regs + SVC_I3C_MSTATUS);
> -
> status = readl(master->regs + SVC_I3C_MSTATUS);
> ibitype = SVC_I3C_MSTATUS_IBITYPE(status);
> ibiaddr = SVC_I3C_MSTATUS_IBIADDR(status);

Thanks,
Miquèl