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[PATCH v1 1/2] i3c: master: svc: Use manual response for IBI events

Stanley Chu posted 2 patches 1 month ago
There is a newer version of this series
[PATCH v1 1/2] i3c: master: svc: Use manual response for IBI events
Posted by Stanley Chu 1 month ago 
From: Stanley Chu <yschu@nuvoton.com>

Driver wants to nack the IBI request when the target is not in the
known address list. In below code, svc_i3c_master_nack_ibi() will
cause undefined behavior when using AUTOIBI with auto response rule,
because hw always auto ack the IBI request.

    switch (ibitype) {
    case SVC_I3C_MSTATUS_IBITYPE_IBI:
            dev = svc_i3c_master_dev_from_addr(master, ibiaddr);
            if (!dev || !is_events_enabled(master, SVC_I3C_EVENT_IBI))
                    svc_i3c_master_nack_ibi(master);
            ...
            break;

AutoIBI has another issue that the controller doesn't quit AutoIBI state
after IBIWON polling timeout when there is a SDA glitch(high->low->high).
1. SDA high->low: raising an interrupt to execute IBI ISR
2. SDA low->high
3. Driver writes an AutoIBI request
4. AutoIBI process does not start because SDA is not low
5. IBIWON polling times out
6. Controller reamins in AutoIBI state and doesn't accept EmitStop request

Emitting broadcast address with IBIRESP_MANUAL avoids both issues.

Signed-off-by: Stanley Chu <yschu@nuvoton.com>
---
 drivers/i3c/master/svc-i3c-master.c | 28 +++++++++++++++++++++++-----
 1 file changed, 23 insertions(+), 5 deletions(-)

diff --git a/drivers/i3c/master/svc-i3c-master.c b/drivers/i3c/master/svc-i3c-master.c
index 701ae165b25b..baf3059fd668 100644
--- a/drivers/i3c/master/svc-i3c-master.c
+++ b/drivers/i3c/master/svc-i3c-master.c
@@ -517,9 +517,22 @@ static void svc_i3c_master_ibi_isr(struct svc_i3c_master *master)
 	 */
 	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,
+	/*
+	 * Write REQUEST_START_ADDR request to emit broadcast address for arbitration,
+	 * instend of using AUTO_IBI.
+	 *
+	 * Using AutoIBI request may cause controller to remain in AutoIBI state when
+	 * there is a glitch on SDA line (high->low->high).
+	 * 1. SDA high->low, raising an interrupt to execute IBI isr.
+	 * 2. SDA low->high.
+	 * 3. IBI isr writes an AutoIBI request.
+	 * 4. The controller will not start AutoIBI process because SDA is not low.
+	 * 5. IBIWON polling times out.
+	 * 6. Controller reamins in AutoIBI state and doesn't accept EmitStop request.
+	 */
+	writel(SVC_I3C_MCTRL_REQUEST_START_ADDR |
+	       SVC_I3C_MCTRL_IBIRESP_MANUAL |
+	       SVC_I3C_MCTRL_ADDR(I3C_BROADCAST_ADDR),
 	       master->regs + SVC_I3C_MCTRL);
 
 	/* Wait for IBIWON, should take approximately 100us */
@@ -539,10 +552,15 @@ static void svc_i3c_master_ibi_isr(struct svc_i3c_master *master)
 	switch (ibitype) {
 	case SVC_I3C_MSTATUS_IBITYPE_IBI:
 		dev = svc_i3c_master_dev_from_addr(master, ibiaddr);
-		if (!dev || !is_events_enabled(master, SVC_I3C_EVENT_IBI))
+		if (!dev || !is_events_enabled(master, SVC_I3C_EVENT_IBI)) {
 			svc_i3c_master_nack_ibi(master);
-		else
+		} else {
+			if (dev->info.bcr & I3C_BCR_IBI_PAYLOAD)
+				svc_i3c_master_ack_ibi(master, true);
+			else
+				svc_i3c_master_ack_ibi(master, false);
 			svc_i3c_master_handle_ibi(master, dev);
+		}
 		break;
 	case SVC_I3C_MSTATUS_IBITYPE_HOT_JOIN:
 		if (is_events_enabled(master, SVC_I3C_EVENT_HOTJOIN))
-- 
2.34.1
Re: [PATCH v1 1/2] i3c: master: svc: Use manual response for IBI events
Posted by Frank Li 1 month ago 
On Thu, Aug 28, 2025 at 04:32:24PM +0800, Stanley Chu wrote:
> From: Stanley Chu <yschu@nuvoton.com>
>
> Driver wants to nack the IBI request when the target is not in the
> known address list. In below code, svc_i3c_master_nack_ibi() will
> cause undefined behavior when using AUTOIBI with auto response rule,
> because hw always auto ack the IBI request.
>
>     switch (ibitype) {
>     case SVC_I3C_MSTATUS_IBITYPE_IBI:
>             dev = svc_i3c_master_dev_from_addr(master, ibiaddr);
>             if (!dev || !is_events_enabled(master, SVC_I3C_EVENT_IBI))
>                     svc_i3c_master_nack_ibi(master);
>             ...
>             break;
>
> AutoIBI has another issue that the controller doesn't quit AutoIBI state
> after IBIWON polling timeout when there is a SDA glitch(high->low->high).
> 1. SDA high->low: raising an interrupt to execute IBI ISR
> 2. SDA low->high
> 3. Driver writes an AutoIBI request
> 4. AutoIBI process does not start because SDA is not low
> 5. IBIWON polling times out
> 6. Controller reamins in AutoIBI state and doesn't accept EmitStop request
>
> Emitting broadcast address with IBIRESP_MANUAL avoids both issues.
>

missed fix tag

> Signed-off-by: Stanley Chu <yschu@nuvoton.com>
> ---
>  drivers/i3c/master/svc-i3c-master.c | 28 +++++++++++++++++++++++-----
>  1 file changed, 23 insertions(+), 5 deletions(-)
>
> diff --git a/drivers/i3c/master/svc-i3c-master.c b/drivers/i3c/master/svc-i3c-master.c
> index 701ae165b25b..baf3059fd668 100644
> --- a/drivers/i3c/master/svc-i3c-master.c
> +++ b/drivers/i3c/master/svc-i3c-master.c
> @@ -517,9 +517,22 @@ static void svc_i3c_master_ibi_isr(struct svc_i3c_master *master)
>  	 */
>  	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,
> +	/*
> +	 * Write REQUEST_START_ADDR request to emit broadcast address for arbitration,
> +	 * instend of using AUTO_IBI.
> +	 *
> +	 * Using AutoIBI request may cause controller to remain in AutoIBI state when
> +	 * there is a glitch on SDA line (high->low->high).
> +	 * 1. SDA high->low, raising an interrupt to execute IBI isr.
> +	 * 2. SDA low->high.
> +	 * 3. IBI isr writes an AutoIBI request.
> +	 * 4. The controller will not start AutoIBI process because SDA is not low.
> +	 * 5. IBIWON polling times out.
> +	 * 6. Controller reamins in AutoIBI state and doesn't accept EmitStop request.
> +	 */
> +	writel(SVC_I3C_MCTRL_REQUEST_START_ADDR |
> +	       SVC_I3C_MCTRL_IBIRESP_MANUAL |
> +	       SVC_I3C_MCTRL_ADDR(I3C_BROADCAST_ADDR),

Suggest build full fields, although these bits is 0, like.
	SVC_I3C_MCTRL_DIR()
	SVC_I3C_MCTRL_TYPE_I3C

Frank

>  	       master->regs + SVC_I3C_MCTRL);
>
>  	/* Wait for IBIWON, should take approximately 100us */
> @@ -539,10 +552,15 @@ static void svc_i3c_master_ibi_isr(struct svc_i3c_master *master)
>  	switch (ibitype) {
>  	case SVC_I3C_MSTATUS_IBITYPE_IBI:
>  		dev = svc_i3c_master_dev_from_addr(master, ibiaddr);
> -		if (!dev || !is_events_enabled(master, SVC_I3C_EVENT_IBI))
> +		if (!dev || !is_events_enabled(master, SVC_I3C_EVENT_IBI)) {
>  			svc_i3c_master_nack_ibi(master);
> -		else
> +		} else {
> +			if (dev->info.bcr & I3C_BCR_IBI_PAYLOAD)
> +				svc_i3c_master_ack_ibi(master, true);
> +			else
> +				svc_i3c_master_ack_ibi(master, false);
>  			svc_i3c_master_handle_ibi(master, dev);
> +		}
>  		break;
>  	case SVC_I3C_MSTATUS_IBITYPE_HOT_JOIN:
>  		if (is_events_enabled(master, SVC_I3C_EVENT_HOTJOIN))
> --
> 2.34.1
>
>
> --
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Patchew 2.1-devel-b67e4c2

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