From: Alexander Hölzl <alexander.hoelzl(a)gmx.net>
The J1939 standard requires the transmission of messages of length 0.
For example proprietary messages are specified with a data length of 0
to 1785. The transmission of such messages is not possible. Sending
results in no error being returned but no corresponding can frame
being generated.
Enable the transmission of zero length J1939 messages. In order to
facilitate this two changes are necessary:
1) If the transmission of a new message is requested from user space
the message is segmented in j1939_sk_send_loop(). Let the segmentation
take into account zero length messages, do not terminate immediately,
queue the corresponding skb.
2) j1939_session_skb_get_by_offset() selects the next skb to transmit
for a session. Take into account that there might be zero length skbs
in the queue.
Signed-off-by: Alexander Hölzl <alexander.hoelzl(a)gmx.net>
Acked-by: Oleksij Rempel <o.rempel(a)pengutronix.de>
Link: https://patch.msgid.link/20250205174651.103238-1-alexander.hoelzl@gmx.net
Fixes: 9d71dd0c7009 ("can: add support of SAE J1939 protocol")
Cc: stable(a)vger.kernel.org
[mkl: commit message rephrased]
Signed-off-by: Marc Kleine-Budde <mkl(a)pengutronix.de>
---
net/can/j1939/socket.c | 4 ++--
net/can/j1939/transport.c | 5 +++--
2 files changed, 5 insertions(+), 4 deletions(-)
diff --git a/net/can/j1939/socket.c b/net/can/j1939/socket.c
index 305dd72c844c..17226b2341d0 100644
--- a/net/can/j1939/socket.c
+++ b/net/can/j1939/socket.c
@@ -1132,7 +1132,7 @@ static int j1939_sk_send_loop(struct j1939_priv *priv, struct sock *sk,
todo_size = size;
- while (todo_size) {
+ do {
struct j1939_sk_buff_cb *skcb;
segment_size = min_t(size_t, J1939_MAX_TP_PACKET_SIZE,
@@ -1177,7 +1177,7 @@ static int j1939_sk_send_loop(struct j1939_priv *priv, struct sock *sk,
todo_size -= segment_size;
session->total_queued_size += segment_size;
- }
+ } while (todo_size);
switch (ret) {
case 0: /* OK */
diff --git a/net/can/j1939/transport.c b/net/can/j1939/transport.c
index 95f7a7e65a73..9b72d118d756 100644
--- a/net/can/j1939/transport.c
+++ b/net/can/j1939/transport.c
@@ -382,8 +382,9 @@ sk_buff *j1939_session_skb_get_by_offset(struct j1939_session *session,
skb_queue_walk(&session->skb_queue, do_skb) {
do_skcb = j1939_skb_to_cb(do_skb);
- if (offset_start >= do_skcb->offset &&
- offset_start < (do_skcb->offset + do_skb->len)) {
+ if ((offset_start >= do_skcb->offset &&
+ offset_start < (do_skcb->offset + do_skb->len)) ||
+ (offset_start == 0 && do_skcb->offset == 0 && do_skb->len == 0)) {
skb = do_skb;
}
}
--
2.47.2
When the device is in a low power state, access to the following
registers takes a long time:
- EP_CFG
- EP_TRADDR
- EP_CMD
- EP_SEL
- EP_STS
- USB_CONF
To address this, the fast register access feature can be enabled by
setting PUSB_PWR_FST_REG_ACCESS bit of the USB_PWR register, which
allows quick access by software. Software is expected to poll on
PUSB_PWR_FST_REG_ACCESS_STAT to ensure that fast register access has
been enabled by the controller. Attempting to access any of the
aforementioned registers after setting PUSB_PWR_FST_REG_ACCESS but
before PUSB_PWR_FST_REG_ACCESS_STAT has been set will result in
undefined behavior and potentially result in system hang.
Hence, poll on PUSB_PWR_FST_REG_ACCESS_STAT before proceeding with
gadget configuration, and exit if it cannot be enabled.
Fixes: b5148d946f45 ("usb: cdns3: gadget: set fast access bit")
Cc: <stable(a)vger.kernel.org>
Signed-off-by: Siddharth Vadapalli <s-vadapalli(a)ti.com>
---
Hello,
This patch is based on commit
92514ef226f5 Merge tag 'for-6.14-rc1-tag' of git://git.kernel.org/pub/scm/linux/kernel/git/kdave/linux
of Mainline Linux.
Regards,
Siddharth.
drivers/usb/cdns3/cdns3-gadget.c | 18 ++++++++++++++++--
1 file changed, 16 insertions(+), 2 deletions(-)
diff --git a/drivers/usb/cdns3/cdns3-gadget.c b/drivers/usb/cdns3/cdns3-gadget.c
index fd1beb10bba7..b62691944272 100644
--- a/drivers/usb/cdns3/cdns3-gadget.c
+++ b/drivers/usb/cdns3/cdns3-gadget.c
@@ -2971,8 +2971,6 @@ static void cdns3_gadget_config(struct cdns3_device *priv_dev)
/* enable generic interrupt*/
writel(USB_IEN_INIT, ®s->usb_ien);
writel(USB_CONF_CLK2OFFDS | USB_CONF_L1DS, ®s->usb_conf);
- /* keep Fast Access bit */
- writel(PUSB_PWR_FST_REG_ACCESS, &priv_dev->regs->usb_pwr);
cdns3_configure_dmult(priv_dev, NULL);
}
@@ -2990,6 +2988,8 @@ static int cdns3_gadget_udc_start(struct usb_gadget *gadget,
struct cdns3_device *priv_dev = gadget_to_cdns3_device(gadget);
unsigned long flags;
enum usb_device_speed max_speed = driver->max_speed;
+ int ret;
+ u32 reg;
spin_lock_irqsave(&priv_dev->lock, flags);
priv_dev->gadget_driver = driver;
@@ -2997,6 +2997,20 @@ static int cdns3_gadget_udc_start(struct usb_gadget *gadget,
/* limit speed if necessary */
max_speed = min(driver->max_speed, gadget->max_speed);
+ /* keep Fast Access bit */
+ writel(PUSB_PWR_FST_REG_ACCESS, &priv_dev->regs->usb_pwr);
+ reg = readl(&priv_dev->regs->usb_pwr);
+ if (!(reg & PUSB_PWR_FST_REG_ACCESS_STAT)) {
+ ret = readl_poll_timeout_atomic(&priv_dev->regs->usb_pwr, reg,
+ (reg & PUSB_PWR_FST_REG_ACCESS_STAT),
+ 10, 1000);
+ if (ret) {
+ dev_err(priv_dev->dev, "Failed to enable fast access\n");
+ spin_unlock_irqrestore(&priv_dev->lock, flags);
+ return ret;
+ }
+ }
+
switch (max_speed) {
case USB_SPEED_FULL:
writel(USB_CONF_SFORCE_FS, &priv_dev->regs->usb_conf);
--
2.43.0