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Date: Tue, 7 May 2024 10:04:24 +0200
From: Miquel Raynal <miquel.raynal@bootlin.com>
To: Frank Li <Frank.Li@nxp.com>
Cc: alexandre.belloni@bootlin.com, conor.culhane@silvaco.com,
 imx@lists.linux.dev, linux-i3c@lists.infradead.org,
 linux-kernel@vger.kernel.org
Subject: Re: [PATCH v2 3/3] i3c: master: svc: fix invalidate IBI type and
 miss call client IBI handler
Message-ID: <20240507100424.611181f1@xps-13>
In-Reply-To: <20240506164009.21375-3-Frank.Li@nxp.com>
References: <20240506164009.21375-1-Frank.Li@nxp.com>
	<20240506164009.21375-3-Frank.Li@nxp.com>
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Hi Frank,

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

> In an In-Band Interrupt (IBI) handle, the code logic is as follows:
>=20
> 1: writel(SVC_I3C_MCTRL_REQUEST_AUTO_IBI | SVC_I3C_MCTRL_IBIRESP_AUTO,
> 	  master->regs + SVC_I3C_MCTRL);
>=20
> 2: ret =3D readl_relaxed_poll_timeout(master->regs + SVC_I3C_MSTATUS, val,
>                                     SVC_I3C_MSTATUS_IBIWON(val), 0, 1000);
> 	...
> 3: ibitype =3D SVC_I3C_MSTATUS_IBITYPE(status);
>    ibiaddr =3D SVC_I3C_MSTATUS_IBIADDR(status);
>=20
> 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.
>=20
> 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().
>=20
> Clear SVC_I3C_MSTATUS_IBIWON before issue SVC_I3C_MCTRL_REQUEST_AUTO_IBI
> to fix this issue.
>=20
> Cc: stable@vger.kernel.org
> Fixes: 5e5e3c92e748 ("i3c: master: svc: fix wrong data return when IBI ha=
ppen during start frame")
> Signed-off-by: Frank Li <Frank.Li@nxp.com>
> ---
>=20
> Notes:
>     Change from v1 to v2
>     - improve comments.
>=20
>  drivers/i3c/master/svc-i3c-master.c | 16 +++++++++++++---
>  1 file changed, 13 insertions(+), 3 deletions(-)
>=20
> 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_stru=
ct *work)
>  	int ret;
> =20
>  	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@bootlin.com>

Thanks,
Miqu=C3=A8l