[PATCH] can: peak_usb: Add support of loopback mode to the PCAN-USB FD family

[PATCH] can: peak_usb: Add support of loopback mode to the PCAN-USB FD family

[Stéphane Grosjean]

From: Stéphane Grosjean <s.grosjean@peak-system.fr>

This commit adds loopback mode support for all PEAK-System USB-to-CAN FD
interfaces.

The implementation follows the same approach as the peak_pciefd driver.
The only difference is local echo handling: on USB devices, transmit
confirmations are provided through USB write acknowledgments rather than
through the reception of a controller-generated loopback frame.

Signed-off-by: Stéphane Grosjean <s.grosjean@peak-system.fr>
---
 drivers/net/can/usb/peak_usb/pcan_usb_fd.c | 14 ++++++++++----
 1 file changed, 10 insertions(+), 4 deletions(-)

diff --git a/drivers/net/can/usb/peak_usb/pcan_usb_fd.c b/drivers/net/can/usb/peak_usb/pcan_usb_fd.c
index 5840623662af..a00ce1f52341 100644
--- a/drivers/net/can/usb/peak_usb/pcan_usb_fd.c
+++ b/drivers/net/can/usb/peak_usb/pcan_usb_fd.c
@@ -934,6 +934,12 @@ static int pcan_usb_fd_encode_msg(struct peak_usb_device *dev,
 	if (dev->can.ctrlmode & CAN_CTRLMODE_ONE_SHOT)
 		tx_msg_flags |= PUCAN_MSG_SINGLE_SHOT;
 
+	/* Request controller loopback and mark the frame as self-received,
+	 * matching the behavior of the peak_pciefd driver.
+	 */
+	if (dev->can.ctrlmode & CAN_CTRLMODE_LOOPBACK)
+		tx_msg_flags |= PUCAN_MSG_LOOPED_BACK | PUCAN_MSG_SELF_RECEIVE;
+
 	tx_msg->flags = cpu_to_le16(tx_msg_flags);
 	tx_msg->channel_dlc = PUCAN_MSG_CHANNEL_DLC(dev->ctrl_idx, dlc);
 	memcpy(tx_msg->d, cfd->data, cfd->len);
@@ -1266,7 +1272,7 @@ const struct peak_usb_adapter pcan_usb_fd = {
 	.ctrlmode_supported = CAN_CTRLMODE_FD |
 			CAN_CTRLMODE_3_SAMPLES | CAN_CTRLMODE_LISTENONLY |
 			CAN_CTRLMODE_ONE_SHOT | CAN_CTRLMODE_CC_LEN8_DLC |
-			CAN_CTRLMODE_BERR_REPORTING,
+			CAN_CTRLMODE_BERR_REPORTING | CAN_CTRLMODE_LOOPBACK,
 	.clock = {
 		.freq = PCAN_UFD_CRYSTAL_HZ,
 	},
@@ -1343,7 +1349,7 @@ const struct peak_usb_adapter pcan_usb_chip = {
 	.ctrlmode_supported = CAN_CTRLMODE_FD |
 		CAN_CTRLMODE_3_SAMPLES | CAN_CTRLMODE_LISTENONLY |
 		CAN_CTRLMODE_ONE_SHOT | CAN_CTRLMODE_CC_LEN8_DLC |
-		CAN_CTRLMODE_BERR_REPORTING,
+		CAN_CTRLMODE_BERR_REPORTING | CAN_CTRLMODE_LOOPBACK,
 	.clock = {
 		.freq = PCAN_UFD_CRYSTAL_HZ,
 	},
@@ -1420,7 +1426,7 @@ const struct peak_usb_adapter pcan_usb_pro_fd = {
 	.ctrlmode_supported = CAN_CTRLMODE_FD |
 			CAN_CTRLMODE_3_SAMPLES | CAN_CTRLMODE_LISTENONLY |
 			CAN_CTRLMODE_ONE_SHOT | CAN_CTRLMODE_CC_LEN8_DLC |
-			CAN_CTRLMODE_BERR_REPORTING,
+			CAN_CTRLMODE_BERR_REPORTING | CAN_CTRLMODE_LOOPBACK,
 	.clock = {
 		.freq = PCAN_UFD_CRYSTAL_HZ,
 	},
@@ -1497,7 +1503,7 @@ const struct peak_usb_adapter pcan_usb_x6 = {
 	.ctrlmode_supported = CAN_CTRLMODE_FD |
 			CAN_CTRLMODE_3_SAMPLES | CAN_CTRLMODE_LISTENONLY |
 			CAN_CTRLMODE_ONE_SHOT | CAN_CTRLMODE_CC_LEN8_DLC |
-			CAN_CTRLMODE_BERR_REPORTING,
+			CAN_CTRLMODE_BERR_REPORTING | CAN_CTRLMODE_LOOPBACK,
 	.clock = {
 		.freq = PCAN_UFD_CRYSTAL_HZ,
 	},

---
base-commit: baf950233c8efcd3807f771ae5dc3cd6f5326278
change-id: 20260930-peak_usb-canfd-loopback-ffffe0ff9015

Best regards,
--  
Stéphane Grosjean <s.grosjean@peak-system.fr>

Re: [PATCH] can: peak_usb: Add support of loopback mode to the PCAN-USB FD family

[Marc Kleine-Budde]

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On 30.09.2026 15:34:48, Stéphane Grosjean wrote:
> From: Stéphane Grosjean <s.grosjean@peak-system.fr>
>
> This commit adds loopback mode support for all PEAK-System USB-to-CAN FD
> interfaces.
>
> The implementation follows the same approach as the peak_pciefd driver.
> The only difference is local echo handling: on USB devices, transmit
> confirmations are provided through USB write acknowledgments rather than
> through the reception of a controller-generated loopback frame.
>
> Signed-off-by: Stéphane Grosjean <s.grosjean@peak-system.fr>
> ---
>  drivers/net/can/usb/peak_usb/pcan_usb_fd.c | 14 ++++++++++----
>  1 file changed, 10 insertions(+), 4 deletions(-)
>
> diff --git a/drivers/net/can/usb/peak_usb/pcan_usb_fd.c b/drivers/net/can/usb/peak_usb/pcan_usb_fd.c
> index 5840623662af..a00ce1f52341 100644
> --- a/drivers/net/can/usb/peak_usb/pcan_usb_fd.c
> +++ b/drivers/net/can/usb/peak_usb/pcan_usb_fd.c
> @@ -934,6 +934,12 @@ static int pcan_usb_fd_encode_msg(struct peak_usb_device *dev,
>  	if (dev->can.ctrlmode & CAN_CTRLMODE_ONE_SHOT)
>  		tx_msg_flags |= PUCAN_MSG_SINGLE_SHOT;
>
> +	/* Request controller loopback and mark the frame as self-received,
> +	 * matching the behavior of the peak_pciefd driver.
> +	 */
> +	if (dev->can.ctrlmode & CAN_CTRLMODE_LOOPBACK)
> +		tx_msg_flags |= PUCAN_MSG_LOOPED_BACK | PUCAN_MSG_SELF_RECEIVE;
> +
>  	tx_msg->flags = cpu_to_le16(tx_msg_flags);
>  	tx_msg->channel_dlc = PUCAN_MSG_CHANNEL_DLC(dev->ctrl_idx, dlc);
>  	memcpy(tx_msg->d, cfd->data, cfd->len);
> @@ -1266,7 +1272,7 @@ const struct peak_usb_adapter pcan_usb_fd = {
>  	.ctrlmode_supported = CAN_CTRLMODE_FD |
>  			CAN_CTRLMODE_3_SAMPLES | CAN_CTRLMODE_LISTENONLY |
>  			CAN_CTRLMODE_ONE_SHOT | CAN_CTRLMODE_CC_LEN8_DLC |
> -			CAN_CTRLMODE_BERR_REPORTING,
> +			CAN_CTRLMODE_BERR_REPORTING | CAN_CTRLMODE_LOOPBACK,

Can you keep the CAN_CTRLMODE sorted by their value?

Please make an incremental patch for the CAN_CTRLMODE_BERR_REPORTING,
I'll squash that...and add CAN_CTRLMODE_LOOPBACK in the appropriate
place.

Marc

-- 
Pengutronix e.K.                 | Marc Kleine-Budde          |
Embedded Linux                   | https://www.pengutronix.de |
Vertretung Nürnberg              | Phone: +49-5121-206917-129 |
Amtsgericht Hildesheim, HRA 2686 | Fax:   +49-5121-206917-9   |

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Re: [PATCH] can: peak_usb: Add support of loopback mode to the PCAN-USB FD family

[Stéphane Grosjean]

> > @@ -1266,7 +1272,7 @@ const struct peak_usb_adapter pcan_usb_fd = {
> >  	.ctrlmode_supported = CAN_CTRLMODE_FD |
> >  			CAN_CTRLMODE_3_SAMPLES | CAN_CTRLMODE_LISTENONLY |
> >  			CAN_CTRLMODE_ONE_SHOT | CAN_CTRLMODE_CC_LEN8_DLC |
> > -			CAN_CTRLMODE_BERR_REPORTING,
> > +			CAN_CTRLMODE_BERR_REPORTING | CAN_CTRLMODE_LOOPBACK,
> 
> Can you keep the CAN_CTRLMODE sorted by their value?
> 
> Please make an incremental patch for the CAN_CTRLMODE_BERR_REPORTING,
> I'll squash that...and add CAN_CTRLMODE_LOOPBACK in the appropriate
> place.
> 
Hello Marc,

Do you want me to post a v2 of this patch with the CAN_CTRLMODE flags sorted by value, or do you prefer a separate incremental patch on top of the bus error reporting series?

> Marc
> 
> --
> Pengutronix e.K.                 | Marc Kleine-Budde          |
> Embedded Linux                   | https://www.pengutronix.de |
> Vertretung Nürnberg              | Phone: +49-5121-206917-129 |
> Amtsgericht Hildesheim, HRA 2686 | Fax:   +49-5121-206917-9   |
> 

Re: [PATCH] can: peak_usb: Add support of loopback mode to the PCAN-USB FD family

[Marc Kleine-Budde]

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On 30.09.2026 16:24:44, Stéphane Grosjean wrote:
> > > @@ -1266,7 +1272,7 @@ const struct peak_usb_adapter pcan_usb_fd = {
> > >  	.ctrlmode_supported = CAN_CTRLMODE_FD |
> > >  			CAN_CTRLMODE_3_SAMPLES | CAN_CTRLMODE_LISTENONLY |
> > >  			CAN_CTRLMODE_ONE_SHOT | CAN_CTRLMODE_CC_LEN8_DLC |
> > > -			CAN_CTRLMODE_BERR_REPORTING,
> > > +			CAN_CTRLMODE_BERR_REPORTING | CAN_CTRLMODE_LOOPBACK,
> >
> > Can you keep the CAN_CTRLMODE sorted by their value?
> >
> > Please make an incremental patch for the CAN_CTRLMODE_BERR_REPORTING,
> > I'll squash that...and add CAN_CTRLMODE_LOOPBACK in the appropriate
> > place.
>
> Do you want me to post a v2 of this patch with the CAN_CTRLMODE flags
> sorted by value, or do you prefer a separate incremental patch on top
> of the bus error reporting series?

Sorry for being unclear. :)

Please a separate incremental patch on top of the bus error reporting
series.

Then post a v2 of the loopback patch on top of the incremental patch.

regards,
Marc

-- 
Pengutronix e.K.                 | Marc Kleine-Budde          |
Embedded Linux                   | https://www.pengutronix.de |
Vertretung Nürnberg              | Phone: +49-5121-206917-129 |
Amtsgericht Hildesheim, HRA 2686 | Fax:   +49-5121-206917-9   |

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