Re: [PATCH 2/6] i3c: master: svc: fix wrong data return when IBI happen during start frame

Miquel Raynal
2023-10-17T14:21:41Z

Hi Frank,

Frank.Li@nxp.com wrote on Mon, 16 Oct 2023 11:32:28 -0400:

> ┌─────┐ ┏──┐ ┏──┐ ┏──┐ ┏──┐ ┏──┐ ┏──┐ ┏──┐ ┏──┐ ┌─────
> SCL: ┘ └─────┛ └──┛ └──┛ └──┛ └──┛ └──┛ └──┛ └──┛ └──┘
> ───┐ ┌─────┐ ┌─────┐ ┌───────────┐
> SDA: └───────────────────────┘ └─────┘ └─────┘ └─────
> xxx╱ ╲╱ ╲╱ ╲╱ ╲╱ ╲
> : xxx╲IBI ╱╲ Addr(0x0a) ╱╲ RW ╱╲NACK╱╲ S ╱
>
> In-Band Interrupt (IBI) occurred and IBI work thread may not to be

If an In-Band... occurs and the IBI work thread is not
immediately scheduled, when svc... initiates an I3C transfer and
attempts...

> scheduled. When svc_i3c_master_priv_xfers() initiates the I3C transfer
> frame and attempts to send address 0x7e, the target interprets it as an
> IBI handler and returns the target address 0x0a.
>
> However, svc_i3c_master_priv_xfers() does not handle this case and proceeds
> with other transfers, resulting in incorrect data being returned.
>
> IBIWON check has been added in svc_i3c_master_xfer(). In case this

Add IBIWON check in svc_...

> situation occurs, a failure is now returned to the driver.

return a failure...

>
> Fixes: dd3c52846d59 ("i3c: master: svc: Add Silvaco I3C master driver")
> Cc: stable@vger.kernel.org
> Signed-off-by: Frank Li <Frank.Li@nxp.com>
> ---
> drivers/i3c/master/svc-i3c-master.c | 20 ++++++++++++++++++++
> 1 file changed, 20 insertions(+)
>
> diff --git a/drivers/i3c/master/svc-i3c-master.c b/drivers/i3c/master/svc-i3c-master.c
> index ebdb3ea1af9d..0f57a5f75e39 100644
> --- a/drivers/i3c/master/svc-i3c-master.c
> +++ b/drivers/i3c/master/svc-i3c-master.c
> @@ -1009,6 +1009,9 @@ static int svc_i3c_master_xfer(struct svc_i3c_master *master,
> u32 reg;
> int ret;
>
> + /* clean SVC_I3C_MINT_IBIWON w1c bits */
> + writel(SVC_I3C_MINT_IBIWON, master->regs + SVC_I3C_MSTATUS);
> +
> writel(SVC_I3C_MCTRL_REQUEST_START_ADDR |
> xfer_type |
> SVC_I3C_MCTRL_IBIRESP_NACK |
> @@ -1027,6 +1030,23 @@ static int svc_i3c_master_xfer(struct svc_i3c_master *master,
> goto emit_stop;
> }
>
> + /*
> + * According to I3C spec ver 1.1.1, 5.1.2.2.3 Consequence of Controller Starting a Frame
> + * with I3C Target Address.
> + *
> + * The I3C Controller normally should start a Frame, the Address may be arbitrated, and so
> + * the Controller shall monitor to see whether an In-Band Interrupt request, a Controller
> + * Role Request (i.e., Secondary Controller requests to become the Active Controller), or
> + * a Hot-Join Request has been made.
> + *
> + * If missed IBIWON check, the wrong data will be return. When IBIWON happen, return falure
> + * and yeild the above events handler.

Typos: yeild and falure

> + */
> + if (SVC_I3C_MSTATUS_IBIWON(reg)) {
> + ret = -ENXIO;
> + goto emit_stop;
> + }
> +
> if (rnw)
> ret = svc_i3c_master_read(master, in, xfer_len);
> else

With all the typos fixed:

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

Thanks,
Miquèl