| Message ID | 20240506164009.21375-3-Frank.Li@nxp.com (mailing list archive) |
|---|---|
| State | Accepted |
| Headers | show |
| Series | [v2,1/3] i3c: Add comment for -EAGAIN in i3c_device_do_priv_xfers() | expand |
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: > > 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@vger.kernel.org > Fixes: 5e5e3c92e748 ("i3c: master: svc: fix wrong data return when IBI happen during start frame") > Signed-off-by: Frank Li <Frank.Li@nxp.com> > --- > > 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@bootlin.com> Thanks, Miquèl
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. + */ + 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 +442,6 @@ 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);
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@vger.kernel.org Fixes: 5e5e3c92e748 ("i3c: master: svc: fix wrong data return when IBI happen during start frame") Signed-off-by: Frank Li <Frank.Li@nxp.com> --- Notes: Change from v1 to v2 - improve comments. drivers/i3c/master/svc-i3c-master.c | 16 +++++++++++++--- 1 file changed, 13 insertions(+), 3 deletions(-)