[PATCH v2 0/4] eUSB2 support

[PATCH v2 0/4] eUSB2 support

[Sakari Ailus]

This series adds support for eUSB2 Double Isochronous IN Bandwidth to the
UVC and xHCI drivers specified in 'USB 2.0 Double Isochronous IN
Bandwidth' ECN. In short, it adds support for new integrated USB2 webcams
that can send twice the data compared to conventional USB2 webcams.

These devices are identified by the device descriptor bcdUSB 0x0220 value.
They have an additional eUSB2 Isochronous Endpoint Companion Descriptor,
and a zero max packet size in regular isoc endpoint descriptor. Support
for parsing that new descriptor was added in commit

c749f058b437 ("USB: core: Add eUSB2 descriptor and parsing in USB core")

This series adds support to UVC, USB core, and xHCI to identify eUSB2
double isoc devices, and allow and set proper max packet, iso frame desc
sizes, bytes per interval, and other values in URBs and xHCI endpoint
contexts needed to support the double data rates for eUSB2 double isoc
devices.

v1 can be found here
<URL:https://lore.kernel.org/linux-usb/20250616093730.2569328-2-mathias.nyman@linux.intel.com/>.

since v1:

- Introduce uvc_endpoint_max_isoc_bpi() to obtain maximum bytes per interval
  value for an endpoint, in a new patch (3rd). This code has been slightly
  reworked from the instance in the UVC driver, adding support for
  SuperSpeedPlus Isochronous Endpoint Companion besides the USB 2.0 Double
  Isochronous In Bandwidth ECN.

- Use uvc_endpoint_max_isoc_bpi() in the UVC driver instead of open-coding
  eUSB2 Double Isochronous In Bandwidth ECNsupport there.

- Use u32 for maximum bpi and related information in the UVC driver -- the
  value could be larger than a 16-bit type can hold.

- Assume max in usb_submit_urb() is a natural number as
  usb_endpoint_maxp() returns only natural numbers (2nd patch).

- Fixed endianness issues in usb_submit_urb() (2nd patch).

- Move the comment on eUSB2 double isoc bw endpoints in
  xhci_get_endpoint_max_burst() to a better location and remove an
  unneeded else clause in the same function (1st patch).

Rai, Amardeep (3):
  xhci: Add host support for eUSB2 double isochronous bandwidth devices
  USB: core: support eUSB2 double bandwidth large isoc URB frames
  USB: Add a function to obtain USB version independent maximum bpi
    value

Tao Q Tao (1):
  media: uvcvideo: eUSB2 double isochronous bandwidth support

 drivers/media/usb/uvc/uvc_driver.c |  4 +-
 drivers/media/usb/uvc/uvc_video.c  | 24 ++----------
 drivers/media/usb/uvc/uvcvideo.h   |  4 +-
 drivers/usb/core/urb.c             | 18 +++++++--
 drivers/usb/host/xhci-caps.h       |  2 +
 drivers/usb/host/xhci-mem.c        | 60 ++++++++++++++++++++++++------
 drivers/usb/host/xhci-ring.c       |  6 +--
 drivers/usb/host/xhci.c            | 16 +++++++-
 drivers/usb/host/xhci.h            | 20 ++++++++++
 include/linux/usb.h                | 22 +++++++++++
 10 files changed, 130 insertions(+), 46 deletions(-)

-- 
2.39.5

[PATCH v2 1/4] xhci: Add host support for eUSB2 double isochronous bandwidth devices

[Sakari Ailus]

From: "Rai, Amardeep" <amardeep.rai@intel.com>

Detect eUSB2 double isoc bw capable hosts and devices, and set the proper
xhci endpoint context values such as 'Mult', 'Max Burst Size', and 'Max
ESIT Payload' to enable the double isochronous bandwidth endpoints.

Intel xHC uses the endpoint context 'Mult' field for eUSB2 isoc
endpoints even if hosts supporting Large ESIT Payload Capability should
normally ignore the mult field.

Signed-off-by: Rai, Amardeep <amardeep.rai@intel.com>
Co-developed-by: Kannappan R <r.kannappan@intel.com>
Signed-off-by: Kannappan R <r.kannappan@intel.com>
Reviewed-by: Sakari Ailus <sakari.ailus@linux.intel.com>
Co-developed-by: Mathias Nyman <mathias.nyman@linux.intel.com>
Signed-off-by: Mathias Nyman <mathias.nyman@linux.intel.com>
Co-developed-by: Sakari Ailus <sakari.ailus@linux.intel.com>
Signed-off-by: Sakari Ailus <sakari.ailus@linux.intel.com>
---
 drivers/usb/host/xhci-caps.h |  2 ++
 drivers/usb/host/xhci-mem.c  | 60 ++++++++++++++++++++++++++++--------
 drivers/usb/host/xhci-ring.c |  6 ++--
 drivers/usb/host/xhci.c      | 16 +++++++++-
 drivers/usb/host/xhci.h      | 20 ++++++++++++
 5 files changed, 88 insertions(+), 16 deletions(-)

diff --git a/drivers/usb/host/xhci-caps.h b/drivers/usb/host/xhci-caps.h
index 4b8ff4815644..723a56052439 100644
--- a/drivers/usb/host/xhci-caps.h
+++ b/drivers/usb/host/xhci-caps.h
@@ -89,3 +89,5 @@
 #define HCC2_GSC(p)             ((p) & (1 << 8))
 /* true: HC support Virtualization Based Trusted I/O Capability */
 #define HCC2_VTC(p)             ((p) & (1 << 9))
+/* true: HC support Double BW on a eUSB2 HS ISOC EP */
+#define HCC2_EUSB2_DIC(p)	((p) & (1 << 11))
diff --git a/drivers/usb/host/xhci-mem.c b/drivers/usb/host/xhci-mem.c
index 6680afa4f596..ea51434c80fa 100644
--- a/drivers/usb/host/xhci-mem.c
+++ b/drivers/usb/host/xhci-mem.c
@@ -1328,18 +1328,36 @@ static unsigned int xhci_get_endpoint_interval(struct usb_device *udev,
 	return interval;
 }
 
-/* The "Mult" field in the endpoint context is only set for SuperSpeed isoc eps.
+/*
+ * xHCs without LEC use the "Mult" field in the endpoint context for SuperSpeed
+ * isoc eps, and High speed isoc eps that support bandwidth doubling. Standard
  * High speed endpoint descriptors can define "the number of additional
  * transaction opportunities per microframe", but that goes in the Max Burst
  * endpoint context field.
  */
-static u32 xhci_get_endpoint_mult(struct usb_device *udev,
-		struct usb_host_endpoint *ep)
+static u32 xhci_get_endpoint_mult(struct xhci_hcd *xhci,
+				  struct usb_device *udev,
+				  struct usb_host_endpoint *ep)
 {
-	if (udev->speed < USB_SPEED_SUPER ||
-			!usb_endpoint_xfer_isoc(&ep->desc))
+	bool lec;
+
+	/* xHCI 1.1 with LEC set does not use mult field, except intel eUSB2 */
+	lec = xhci->hci_version > 0x100 && HCC2_LEC(xhci->hcc_params2);
+
+	/* eUSB2 double isoc bw devices are the only USB2 devices using mult */
+	if (xhci_eusb2_is_isoc_bw_double(udev, ep)) {
+		if (!lec || xhci->quirks & XHCI_INTEL_HOST)
+			return 1;
+	}
+
+	/* Oherwise only isoc transfers on hosts without LEC uses mult field */
+	if (!usb_endpoint_xfer_isoc(&ep->desc) || lec)
 		return 0;
-	return ep->ss_ep_comp.bmAttributes;
+
+	if (udev->speed >= USB_SPEED_SUPER)
+		return ep->ss_ep_comp.bmAttributes;
+
+	return 0;
 }
 
 static u32 xhci_get_endpoint_max_burst(struct usb_device *udev,
@@ -1351,8 +1369,18 @@ static u32 xhci_get_endpoint_max_burst(struct usb_device *udev,
 
 	if (udev->speed == USB_SPEED_HIGH &&
 	    (usb_endpoint_xfer_isoc(&ep->desc) ||
-	     usb_endpoint_xfer_int(&ep->desc)))
+	     usb_endpoint_xfer_int(&ep->desc))) {
+		/*
+		 * eUSB2 double isoc bw endpoints max packet field service
+		 * opportunity bits 12:11 are not valid, so set the ctx burst to
+		 * max service opportunity "2" as these eps support transferring
+		 * over 3072 bytes per interval
+		 */
+		if (xhci_eusb2_is_isoc_bw_double(udev, ep))
+			return 2;
+
 		return usb_endpoint_maxp_mult(&ep->desc) - 1;
+	}
 
 	return 0;
 }
@@ -1400,6 +1428,10 @@ static u32 xhci_get_max_esit_payload(struct usb_device *udev,
 	if (udev->speed >= USB_SPEED_SUPER)
 		return le16_to_cpu(ep->ss_ep_comp.wBytesPerInterval);
 
+	/* High speed eUSB2 double isoc bw with over 3072 bytes per esit */
+	if (xhci_eusb2_is_isoc_bw_double(udev, ep))
+		return le32_to_cpu(ep->eusb2_isoc_ep_comp.dwBytesPerInterval);
+
 	max_packet = usb_endpoint_maxp(&ep->desc);
 	max_burst = usb_endpoint_maxp_mult(&ep->desc);
 	/* A 0 in max burst means 1 transfer per ESIT */
@@ -1437,6 +1469,13 @@ int xhci_endpoint_init(struct xhci_hcd *xhci,
 
 	ring_type = usb_endpoint_type(&ep->desc);
 
+	/* Ensure host supports double isoc bandwidth for eUSB2 devices */
+	if (xhci_eusb2_is_isoc_bw_double(udev, ep) &&
+	    !HCC2_EUSB2_DIC(xhci->hcc_params2))	{
+		dev_dbg(&udev->dev, "Double Isoc Bandwidth not supported by xhci\n");
+		return -EINVAL;
+	}
+
 	/*
 	 * Get values to fill the endpoint context, mostly from ep descriptor.
 	 * The average TRB buffer lengt for bulk endpoints is unclear as we
@@ -1460,8 +1499,8 @@ int xhci_endpoint_init(struct xhci_hcd *xhci,
 		}
 	}
 
-	mult = xhci_get_endpoint_mult(udev, ep);
-	max_packet = usb_endpoint_maxp(&ep->desc);
+	mult = xhci_get_endpoint_mult(xhci, udev, ep);
+	max_packet = xhci_usb_endpoint_maxp(udev, ep);
 	max_burst = xhci_get_endpoint_max_burst(udev, ep);
 	avg_trb_len = max_esit_payload;
 
@@ -1482,9 +1521,6 @@ int xhci_endpoint_init(struct xhci_hcd *xhci,
 	/* xHCI 1.0 and 1.1 indicates that ctrl ep avg TRB Length should be 8 */
 	if (usb_endpoint_xfer_control(&ep->desc) && xhci->hci_version >= 0x100)
 		avg_trb_len = 8;
-	/* xhci 1.1 with LEC support doesn't use mult field, use RsvdZ */
-	if ((xhci->hci_version > 0x100) && HCC2_LEC(xhci->hcc_params2))
-		mult = 0;
 
 	/* Set up the endpoint ring */
 	virt_dev->eps[ep_index].new_ring =
diff --git a/drivers/usb/host/xhci-ring.c b/drivers/usb/host/xhci-ring.c
index 94c9c9271658..9abc5bc4e1c0 100644
--- a/drivers/usb/host/xhci-ring.c
+++ b/drivers/usb/host/xhci-ring.c
@@ -3542,7 +3542,7 @@ static u32 xhci_td_remainder(struct xhci_hcd *xhci, int transferred,
 	if ((xhci->quirks & XHCI_MTK_HOST) && (xhci->hci_version < 0x100))
 		trb_buff_len = 0;
 
-	maxp = usb_endpoint_maxp(&urb->ep->desc);
+	maxp = xhci_usb_endpoint_maxp(urb->dev, urb->ep);
 	total_packet_count = DIV_ROUND_UP(td_total_len, maxp);
 
 	/* Queueing functions don't count the current TRB into transferred */
@@ -3559,7 +3559,7 @@ static int xhci_align_td(struct xhci_hcd *xhci, struct urb *urb, u32 enqd_len,
 	u32 new_buff_len;
 	size_t len;
 
-	max_pkt = usb_endpoint_maxp(&urb->ep->desc);
+	max_pkt = xhci_usb_endpoint_maxp(urb->dev, urb->ep);
 	unalign = (enqd_len + *trb_buff_len) % max_pkt;
 
 	/* we got lucky, last normal TRB data on segment is packet aligned */
@@ -4130,7 +4130,7 @@ static int xhci_queue_isoc_tx(struct xhci_hcd *xhci, gfp_t mem_flags,
 		addr = start_addr + urb->iso_frame_desc[i].offset;
 		td_len = urb->iso_frame_desc[i].length;
 		td_remain_len = td_len;
-		max_pkt = usb_endpoint_maxp(&urb->ep->desc);
+		max_pkt = xhci_usb_endpoint_maxp(urb->dev, urb->ep);
 		total_pkt_count = DIV_ROUND_UP(td_len, max_pkt);
 
 		/* A zero-length transfer still involves at least one packet. */
diff --git a/drivers/usb/host/xhci.c b/drivers/usb/host/xhci.c
index 8a819e853288..1ea7d2fb5876 100644
--- a/drivers/usb/host/xhci.c
+++ b/drivers/usb/host/xhci.c
@@ -1332,7 +1332,7 @@ static bool xhci_urb_temp_buffer_required(struct usb_hcd *hcd,
 	struct scatterlist *tail_sg;
 
 	tail_sg = urb->sg;
-	max_pkt = usb_endpoint_maxp(&urb->ep->desc);
+	max_pkt = xhci_usb_endpoint_maxp(urb->dev, urb->ep);
 
 	if (!urb->num_sgs)
 		return ret;
@@ -2920,6 +2920,20 @@ int xhci_stop_endpoint_sync(struct xhci_hcd *xhci, struct xhci_virt_ep *ep, int
 }
 EXPORT_SYMBOL_GPL(xhci_stop_endpoint_sync);
 
+/*
+ * xhci_usb_endpoint_maxp - get endpoint max packet size
+ * @host_ep: USB host endpoint to be checked
+ *
+ * Returns max packet from the correct descriptor
+ */
+int xhci_usb_endpoint_maxp(struct usb_device *udev,
+			   struct usb_host_endpoint *host_ep)
+{
+	if (xhci_eusb2_is_isoc_bw_double(udev, host_ep))
+		return le16_to_cpu(host_ep->eusb2_isoc_ep_comp.wMaxPacketSize);
+	return usb_endpoint_maxp(&host_ep->desc);
+}
+
 /* Issue a configure endpoint command or evaluate context command
  * and wait for it to finish.
  */
diff --git a/drivers/usb/host/xhci.h b/drivers/usb/host/xhci.h
index a20f4e7cd43a..498b6f6cb7fb 100644
--- a/drivers/usb/host/xhci.h
+++ b/drivers/usb/host/xhci.h
@@ -1736,6 +1736,24 @@ static inline bool xhci_has_one_roothub(struct xhci_hcd *xhci)
 	       (!xhci->usb2_rhub.num_ports || !xhci->usb3_rhub.num_ports);
 }
 
+/*
+ * USB 2.0 specification, chapter 5.6.4 Isochronous Transfer Bus Access
+ * Constraint. A high speed endpoint can move up to 3072 bytes per microframe
+ * (or 192Mb/s).
+ */
+#define MAX_ISOC_XFER_SIZE_HS  3072
+
+static inline bool xhci_eusb2_is_isoc_bw_double(struct usb_device *udev,
+						struct usb_host_endpoint *ep)
+{
+	return le16_to_cpu(udev->descriptor.bcdUSB) == 0x220 &&
+		udev->speed == USB_SPEED_HIGH &&
+		usb_endpoint_xfer_isoc(&ep->desc) &&
+		le16_to_cpu(ep->desc.wMaxPacketSize) == 0 &&
+		le32_to_cpu(ep->eusb2_isoc_ep_comp.dwBytesPerInterval) >
+		MAX_ISOC_XFER_SIZE_HS;
+}
+
 #define xhci_dbg(xhci, fmt, args...) \
 	dev_dbg(xhci_to_hcd(xhci)->self.controller , fmt , ## args)
 #define xhci_err(xhci, fmt, args...) \
@@ -1957,6 +1975,8 @@ void xhci_update_erst_dequeue(struct xhci_hcd *xhci,
 			      struct xhci_interrupter *ir,
 			      bool clear_ehb);
 void xhci_add_interrupter(struct xhci_hcd *xhci, unsigned int intr_num);
+int xhci_usb_endpoint_maxp(struct usb_device *udev,
+			   struct usb_host_endpoint *host_ep);
 
 /* xHCI roothub code */
 void xhci_set_link_state(struct xhci_hcd *xhci, struct xhci_port *port,
-- 
2.39.5

[PATCH v2 2/4] USB: core: support eUSB2 double bandwidth large isoc URB frames

[Sakari Ailus]

From: "Rai, Amardeep" <amardeep.rai@intel.com>

eUSB2 double isochronous in bandwidth devices support up to 6 transactions
per microframe, and thus doubles the total bytes possible to receive per
microframe.

Support larger URB isoc frame sizes for eUSB2 double isoc in endpoints.

Also usb_endpoint_maxp() returns a natural number so there's no need to
assume it could be < 0.

Signed-off-by: Rai, Amardeep <amardeep.rai@intel.com>
Reviewed-by: Sakari Ailus <sakari.ailus@linux.intel.com>
Signed-off-by: Mathias Nyman <mathias.nyman@linux.intel.com>
Co-developed-by: Sakari Ailus <sakari.ailus@linux.intel.com>
Signed-off-by: Sakari Ailus <sakari.ailus@linux.intel.com>
---
 drivers/usb/core/urb.c | 18 ++++++++++++++----
 1 file changed, 14 insertions(+), 4 deletions(-)

diff --git a/drivers/usb/core/urb.c b/drivers/usb/core/urb.c
index 7a76d5a62db1..2c8698cc452c 100644
--- a/drivers/usb/core/urb.c
+++ b/drivers/usb/core/urb.c
@@ -372,6 +372,7 @@ int usb_submit_urb(struct urb *urb, gfp_t mem_flags)
 	struct usb_host_endpoint	*ep;
 	int				is_out;
 	unsigned int			allowed;
+	bool				is_eusb2_isoch_double;
 
 	if (!urb || !urb->complete)
 		return -EINVAL;
@@ -434,7 +435,12 @@ int usb_submit_urb(struct urb *urb, gfp_t mem_flags)
 		return -ENODEV;
 
 	max = usb_endpoint_maxp(&ep->desc);
-	if (max <= 0) {
+	is_eusb2_isoch_double = dev->speed == USB_SPEED_HIGH &&
+				xfertype == USB_ENDPOINT_XFER_ISOC &&
+				usb_endpoint_dir_in(&ep->desc) &&
+				le16_to_cpu(dev->descriptor.bcdUSB) == 0x220 &&
+				le16_to_cpu(ep->desc.wMaxPacketSize) == 0;
+	if (!max && !is_eusb2_isoch_double) {
 		dev_dbg(&dev->dev,
 			"bogus endpoint ep%d%s in %s (bad maxpacket %d)\n",
 			usb_endpoint_num(&ep->desc), is_out ? "out" : "in",
@@ -467,9 +473,13 @@ int usb_submit_urb(struct urb *urb, gfp_t mem_flags)
 			max = le32_to_cpu(isoc_ep_comp->dwBytesPerInterval);
 		}
 
-		/* "high bandwidth" mode, 1-3 packets/uframe? */
-		if (dev->speed == USB_SPEED_HIGH)
-			max *= usb_endpoint_maxp_mult(&ep->desc);
+		/* High speed, 1-3 packets/uframe, max 6 for eUSB2 double bw */
+		if (dev->speed == USB_SPEED_HIGH) {
+			if (is_eusb2_isoch_double)
+				max = le32_to_cpu(ep->eusb2_isoc_ep_comp.dwBytesPerInterval);
+			else
+				max *= usb_endpoint_maxp_mult(&ep->desc);
+		}
 
 		if (urb->number_of_packets <= 0)
 			return -EINVAL;
-- 
2.39.5

[PATCH v2 3/4] USB: Add a function to obtain USB version independent maximum bpi value

[Sakari Ailus]

From: "Rai, Amardeep" <amardeep.rai@intel.com>

Add usb_endpoint_max_isoc_bpi() to obtain maximum bytes per interval for
isochronous endpoints in a USB version independent way.

Signed-off-by: Rai, Amardeep <amardeep.rai@intel.com>
Signed-off-by: Mathias Nyman <mathias.nyman@linux.intel.com>
Co-developed-by: Sakari Ailus <sakari.ailus@linux.intel.com>
Signed-off-by: Sakari Ailus <sakari.ailus@linux.intel.com>
---
 include/linux/usb.h | 22 ++++++++++++++++++++++
 1 file changed, 22 insertions(+)

diff --git a/include/linux/usb.h b/include/linux/usb.h
index 68166718ab30..bd70bd5ca82d 100644
--- a/include/linux/usb.h
+++ b/include/linux/usb.h
@@ -2038,6 +2038,28 @@ static inline int usb_translate_errors(int error_code)
 	}
 }
 
+static inline u32 usb_endpoint_max_isoc_bpi(struct usb_device *dev,
+					    const struct usb_host_endpoint *ep)
+{
+	if (usb_endpoint_type(&ep->desc) != USB_ENDPOINT_XFER_ISOC)
+		return 0;
+
+	switch (dev->speed) {
+	case USB_SPEED_SUPER_PLUS:
+		if (USB_SS_SSP_ISOC_COMP(ep->ss_ep_comp.bmAttributes))
+			return le32_to_cpu(ep->ssp_isoc_ep_comp.dwBytesPerInterval);
+		fallthrough;
+	case USB_SPEED_SUPER:
+		return le16_to_cpu(ep->ss_ep_comp.wBytesPerInterval);
+	case USB_SPEED_HIGH:
+		if (!usb_endpoint_maxp(&ep->desc) && le16_to_cpu(dev->descriptor.bcdUSB) == 0x220)
+			return le32_to_cpu(ep->eusb2_isoc_ep_comp.dwBytesPerInterval);
+		fallthrough;
+	default:
+		return usb_endpoint_maxp(&ep->desc) * usb_endpoint_maxp_mult(&ep->desc);
+	}
+}
+
 /* Events from the usb core */
 #define USB_DEVICE_ADD		0x0001
 #define USB_DEVICE_REMOVE	0x0002
-- 
2.39.5

[PATCH v2 4/4] media: uvcvideo: eUSB2 double isochronous bandwidth support

[Sakari Ailus]

From: Tao Q Tao <tao.q.tao@intel.com>

Use usb_endpoint_max_isoc_bpi() from the USB framework to find the maximum
bytes per interval for the endpoint. Consequently this adds eUSB2
isochronous mode and SuperSpeedPlus Isochronous Endpoint Compaion support
where larger bpi values are possible.

Co-developed-by: Amardeep Rai <amardeep.rai@intel.com>
Signed-off-by: Amardeep Rai <amardeep.rai@intel.com>
Signed-off-by: Tao Q Tao <tao.q.tao@intel.com>
Signed-off-by: Mathias Nyman <mathias.nyman@linux.intel.com>
Co-developed-by: Sakari Ailus <sakari.ailus@linux.intel.com>
Signed-off-by: Sakari Ailus <sakari.ailus@linux.intel.com>
Reviewed-by: Ilpo Järvinen <ilpo.jarvinen@linux.intel.com>
---
 drivers/media/usb/uvc/uvc_driver.c |  4 ++--
 drivers/media/usb/uvc/uvc_video.c  | 24 +++---------------------
 drivers/media/usb/uvc/uvcvideo.h   |  4 +---
 3 files changed, 6 insertions(+), 26 deletions(-)

diff --git a/drivers/media/usb/uvc/uvc_driver.c b/drivers/media/usb/uvc/uvc_driver.c
index da24a655ab68..fde0bc95622c 100644
--- a/drivers/media/usb/uvc/uvc_driver.c
+++ b/drivers/media/usb/uvc/uvc_driver.c
@@ -536,7 +536,7 @@ static int uvc_parse_streaming(struct uvc_device *dev,
 	unsigned int nformats = 0, nframes = 0, nintervals = 0;
 	unsigned int size, i, n, p;
 	u32 *interval;
-	u16 psize;
+	u32 psize;
 	int ret = -EINVAL;
 
 	if (intf->cur_altsetting->desc.bInterfaceSubClass
@@ -772,7 +772,7 @@ static int uvc_parse_streaming(struct uvc_device *dev,
 				streaming->header.bEndpointAddress);
 		if (ep == NULL)
 			continue;
-		psize = uvc_endpoint_max_bpi(dev->udev, ep);
+		psize = usb_endpoint_max_isoc_bpi(dev->udev, ep);
 		if (psize > streaming->maxpsize)
 			streaming->maxpsize = psize;
 	}
diff --git a/drivers/media/usb/uvc/uvc_video.c b/drivers/media/usb/uvc/uvc_video.c
index e3567aeb0007..9f65cdbc1a1c 100644
--- a/drivers/media/usb/uvc/uvc_video.c
+++ b/drivers/media/usb/uvc/uvc_video.c
@@ -1895,24 +1895,6 @@ static void uvc_video_stop_transfer(struct uvc_streaming *stream,
 		uvc_free_urb_buffers(stream);
 }
 
-/*
- * Compute the maximum number of bytes per interval for an endpoint.
- */
-u16 uvc_endpoint_max_bpi(struct usb_device *dev, struct usb_host_endpoint *ep)
-{
-	u16 psize;
-
-	switch (dev->speed) {
-	case USB_SPEED_SUPER:
-	case USB_SPEED_SUPER_PLUS:
-		return le16_to_cpu(ep->ss_ep_comp.wBytesPerInterval);
-	default:
-		psize = usb_endpoint_maxp(&ep->desc);
-		psize *= usb_endpoint_maxp_mult(&ep->desc);
-		return psize;
-	}
-}
-
 /*
  * Initialize isochronous URBs and allocate transfer buffers. The packet size
  * is given by the endpoint.
@@ -1923,10 +1905,10 @@ static int uvc_init_video_isoc(struct uvc_streaming *stream,
 	struct urb *urb;
 	struct uvc_urb *uvc_urb;
 	unsigned int npackets, i;
-	u16 psize;
+	u32 psize;
 	u32 size;
 
-	psize = uvc_endpoint_max_bpi(stream->dev->udev, ep);
+	psize = usb_endpoint_max_isoc_bpi(stream->dev->udev, ep);
 	size = stream->ctrl.dwMaxVideoFrameSize;
 
 	npackets = uvc_alloc_urb_buffers(stream, size, psize, gfp_flags);
@@ -2067,7 +2049,7 @@ static int uvc_video_start_transfer(struct uvc_streaming *stream,
 				continue;
 
 			/* Check if the bandwidth is high enough. */
-			psize = uvc_endpoint_max_bpi(stream->dev->udev, ep);
+			psize = usb_endpoint_max_isoc_bpi(stream->dev->udev, ep);
 			if (psize >= bandwidth && psize < best_psize) {
 				altsetting = alts->desc.bAlternateSetting;
 				best_psize = psize;
diff --git a/drivers/media/usb/uvc/uvcvideo.h b/drivers/media/usb/uvc/uvcvideo.h
index b9f8eb62ba1d..a77ba76e033a 100644
--- a/drivers/media/usb/uvc/uvcvideo.h
+++ b/drivers/media/usb/uvc/uvcvideo.h
@@ -450,7 +450,7 @@ struct uvc_streaming {
 
 	struct usb_interface *intf;
 	int intfnum;
-	u16 maxpsize;
+	u32 maxpsize;
 
 	struct uvc_streaming_header header;
 	enum v4l2_buf_type type;
@@ -818,8 +818,6 @@ void uvc_ctrl_cleanup_fh(struct uvc_fh *handle);
 /* Utility functions */
 struct usb_host_endpoint *uvc_find_endpoint(struct usb_host_interface *alts,
 					    u8 epaddr);
-u16 uvc_endpoint_max_bpi(struct usb_device *dev, struct usb_host_endpoint *ep);
-
 /* Quirks support */
 void uvc_video_decode_isight(struct uvc_urb *uvc_urb,
 			     struct uvc_buffer *buf,
-- 
2.39.5

Re: [PATCH v2 3/4] USB: Add a function to obtain USB version independent maximum bpi value

[Hans de Goede]

Hi Sarari,

On 11-Jul-25 10:34 AM, Sakari Ailus wrote:
> From: "Rai, Amardeep" <amardeep.rai@intel.com>
> 
> Add usb_endpoint_max_isoc_bpi() to obtain maximum bytes per interval for
> isochronous endpoints in a USB version independent way.

Nice, thank you for adding a generic helper for this.

> Signed-off-by: Rai, Amardeep <amardeep.rai@intel.com>
> Signed-off-by: Mathias Nyman <mathias.nyman@linux.intel.com>
> Co-developed-by: Sakari Ailus <sakari.ailus@linux.intel.com>
> Signed-off-by: Sakari Ailus <sakari.ailus@linux.intel.com>
> ---
>  include/linux/usb.h | 22 ++++++++++++++++++++++
>  1 file changed, 22 insertions(+)
> 
> diff --git a/include/linux/usb.h b/include/linux/usb.h
> index 68166718ab30..bd70bd5ca82d 100644
> --- a/include/linux/usb.h
> +++ b/include/linux/usb.h
> @@ -2038,6 +2038,28 @@ static inline int usb_translate_errors(int error_code)
>  	}
>  }
>  
> +static inline u32 usb_endpoint_max_isoc_bpi(struct usb_device *dev,
> +					    const struct usb_host_endpoint *ep)
> +{
> +	if (usb_endpoint_type(&ep->desc) != USB_ENDPOINT_XFER_ISOC)
> +		return 0;
> +
> +	switch (dev->speed) {
> +	case USB_SPEED_SUPER_PLUS:
> +		if (USB_SS_SSP_ISOC_COMP(ep->ss_ep_comp.bmAttributes))
> +			return le32_to_cpu(ep->ssp_isoc_ep_comp.dwBytesPerInterval);
> +		fallthrough;
> +	case USB_SPEED_SUPER:
> +		return le16_to_cpu(ep->ss_ep_comp.wBytesPerInterval);
> +	case USB_SPEED_HIGH:
> +		if (!usb_endpoint_maxp(&ep->desc) && le16_to_cpu(dev->descriptor.bcdUSB) == 0x220)
> +			return le32_to_cpu(ep->eusb2_isoc_ep_comp.dwBytesPerInterval);

Shouldn't there be a check here that ep->eusb2_isoc_ep_comp is filled?

Like how the USB_SPEED_SUPER_PLU code above checks
USB_SS_SSP_ISOC_COMP(ep->ss_ep_comp.bmAttributes)?

I know you check the bcdUSB, but in my experience that field sometimes
contains made up numbers, so I was wondering if there is an extra check
we can do here ?

Regards,

Hans



> +		fallthrough;
> +	default:
> +		return usb_endpoint_maxp(&ep->desc) * usb_endpoint_maxp_mult(&ep->desc);
> +	}
> +}
> +
>  /* Events from the usb core */
>  #define USB_DEVICE_ADD		0x0001
>  #define USB_DEVICE_REMOVE	0x0002

Re: [PATCH v2 3/4] USB: Add a function to obtain USB version independent maximum bpi value

[Alan Stern]

On Fri, Jul 11, 2025 at 11:34:12AM +0300, Sakari Ailus wrote:
> From: "Rai, Amardeep" <amardeep.rai@intel.com>
> 
> Add usb_endpoint_max_isoc_bpi() to obtain maximum bytes per interval for
> isochronous endpoints in a USB version independent way.
> 
> Signed-off-by: Rai, Amardeep <amardeep.rai@intel.com>
> Signed-off-by: Mathias Nyman <mathias.nyman@linux.intel.com>
> Co-developed-by: Sakari Ailus <sakari.ailus@linux.intel.com>
> Signed-off-by: Sakari Ailus <sakari.ailus@linux.intel.com>
> ---
>  include/linux/usb.h | 22 ++++++++++++++++++++++
>  1 file changed, 22 insertions(+)
> 
> diff --git a/include/linux/usb.h b/include/linux/usb.h
> index 68166718ab30..bd70bd5ca82d 100644
> --- a/include/linux/usb.h
> +++ b/include/linux/usb.h
> @@ -2038,6 +2038,28 @@ static inline int usb_translate_errors(int error_code)
>  	}
>  }
>  
> +static inline u32 usb_endpoint_max_isoc_bpi(struct usb_device *dev,
> +					    const struct usb_host_endpoint *ep)

The name "usb_endpoint_max_isoc_bpi" is sufficiently obscure that it 
deserves a kerneldoc comment saying what the function does.

Alan Stern

Re: [PATCH v2 3/4] USB: Add a function to obtain USB version independent maximum bpi value

[Sakari Ailus]

Hi Hans,

Thank you for the review.

On Fri, Jul 11, 2025 at 03:44:21PM +0200, Hans de Goede wrote:
> Hi Sarari,
> 
> On 11-Jul-25 10:34 AM, Sakari Ailus wrote:
> > From: "Rai, Amardeep" <amardeep.rai@intel.com>
> > 
> > Add usb_endpoint_max_isoc_bpi() to obtain maximum bytes per interval for
> > isochronous endpoints in a USB version independent way.
> 
> Nice, thank you for adding a generic helper for this.
> 
> > Signed-off-by: Rai, Amardeep <amardeep.rai@intel.com>
> > Signed-off-by: Mathias Nyman <mathias.nyman@linux.intel.com>
> > Co-developed-by: Sakari Ailus <sakari.ailus@linux.intel.com>
> > Signed-off-by: Sakari Ailus <sakari.ailus@linux.intel.com>
> > ---
> >  include/linux/usb.h | 22 ++++++++++++++++++++++
> >  1 file changed, 22 insertions(+)
> > 
> > diff --git a/include/linux/usb.h b/include/linux/usb.h
> > index 68166718ab30..bd70bd5ca82d 100644
> > --- a/include/linux/usb.h
> > +++ b/include/linux/usb.h
> > @@ -2038,6 +2038,28 @@ static inline int usb_translate_errors(int error_code)
> >  	}
> >  }
> >  
> > +static inline u32 usb_endpoint_max_isoc_bpi(struct usb_device *dev,
> > +					    const struct usb_host_endpoint *ep)
> > +{
> > +	if (usb_endpoint_type(&ep->desc) != USB_ENDPOINT_XFER_ISOC)
> > +		return 0;
> > +
> > +	switch (dev->speed) {
> > +	case USB_SPEED_SUPER_PLUS:
> > +		if (USB_SS_SSP_ISOC_COMP(ep->ss_ep_comp.bmAttributes))
> > +			return le32_to_cpu(ep->ssp_isoc_ep_comp.dwBytesPerInterval);
> > +		fallthrough;
> > +	case USB_SPEED_SUPER:
> > +		return le16_to_cpu(ep->ss_ep_comp.wBytesPerInterval);
> > +	case USB_SPEED_HIGH:
> > +		if (!usb_endpoint_maxp(&ep->desc) && le16_to_cpu(dev->descriptor.bcdUSB) == 0x220)
> > +			return le32_to_cpu(ep->eusb2_isoc_ep_comp.dwBytesPerInterval);
> 
> Shouldn't there be a check here that ep->eusb2_isoc_ep_comp is filled?
> 
> Like how the USB_SPEED_SUPER_PLU code above checks
> USB_SS_SSP_ISOC_COMP(ep->ss_ep_comp.bmAttributes)?
> 
> I know you check the bcdUSB, but in my experience that field sometimes
> contains made up numbers, so I was wondering if there is an extra check
> we can do here ?

In the case of eUSB2, there's no such flag as for the SuperSpeedPlus
Isochronous Endpoint Companion. The eUSB2 Isochronous Endpoint Companion
Descriptor is simply expected to be present on eUSB2 (bcdUSB check)
isochronous IN endpoints that support more than 3KB per microframe.

Also what the USB_SS_SSP_ISOC_COMP() macro returns actually dependens on
the device telling there's such a descriptor but it's still different from
the device actually providing one. But what would you do if the device
indicates it provides no SSP_ISOC_COMP descriptor but still does provide
one?

How about adding a flag (or maybe a bit field?) to tell which endpoint
descriptors have been actually filled in struct usb_host_endpoint? I might
do that as a separate patch on top...

I wonder what Mathias thinks, too.

-- 
Kind regards,

Sakari Ailus

Re: [PATCH v2 4/4] media: uvcvideo: eUSB2 double isochronous bandwidth support

[Laurent Pinchart]

Hi Sakari, Tao,

Thank you for the patch.

On Fri, Jul 11, 2025 at 11:34:13AM +0300, Sakari Ailus wrote:
> From: Tao Q Tao <tao.q.tao@intel.com>
> 
> Use usb_endpoint_max_isoc_bpi() from the USB framework to find the maximum
> bytes per interval for the endpoint. Consequently this adds eUSB2
> isochronous mode and SuperSpeedPlus Isochronous Endpoint Compaion support
> where larger bpi values are possible.
> 
> Co-developed-by: Amardeep Rai <amardeep.rai@intel.com>
> Signed-off-by: Amardeep Rai <amardeep.rai@intel.com>
> Signed-off-by: Tao Q Tao <tao.q.tao@intel.com>
> Signed-off-by: Mathias Nyman <mathias.nyman@linux.intel.com>
> Co-developed-by: Sakari Ailus <sakari.ailus@linux.intel.com>
> Signed-off-by: Sakari Ailus <sakari.ailus@linux.intel.com>
> Reviewed-by: Ilpo Järvinen <ilpo.jarvinen@linux.intel.com>

Assuming usb_endpoint_max_isoc_bpi() works correctly :-),

Reviewed-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>

I won't queue this patch for the time being as it depends on the rest of
the series. Please let me know if I should queue it at a later point, or
if you would like to merge it through the linux-usb tree. We would need
to make sure there's no conflict with other scheduled patches for that
kernel development cycle.

> ---
>  drivers/media/usb/uvc/uvc_driver.c |  4 ++--
>  drivers/media/usb/uvc/uvc_video.c  | 24 +++---------------------
>  drivers/media/usb/uvc/uvcvideo.h   |  4 +---
>  3 files changed, 6 insertions(+), 26 deletions(-)
> 
> diff --git a/drivers/media/usb/uvc/uvc_driver.c b/drivers/media/usb/uvc/uvc_driver.c
> index da24a655ab68..fde0bc95622c 100644
> --- a/drivers/media/usb/uvc/uvc_driver.c
> +++ b/drivers/media/usb/uvc/uvc_driver.c
> @@ -536,7 +536,7 @@ static int uvc_parse_streaming(struct uvc_device *dev,
>  	unsigned int nformats = 0, nframes = 0, nintervals = 0;
>  	unsigned int size, i, n, p;
>  	u32 *interval;
> -	u16 psize;
> +	u32 psize;
>  	int ret = -EINVAL;
>  
>  	if (intf->cur_altsetting->desc.bInterfaceSubClass
> @@ -772,7 +772,7 @@ static int uvc_parse_streaming(struct uvc_device *dev,
>  				streaming->header.bEndpointAddress);
>  		if (ep == NULL)
>  			continue;
> -		psize = uvc_endpoint_max_bpi(dev->udev, ep);
> +		psize = usb_endpoint_max_isoc_bpi(dev->udev, ep);
>  		if (psize > streaming->maxpsize)
>  			streaming->maxpsize = psize;
>  	}
> diff --git a/drivers/media/usb/uvc/uvc_video.c b/drivers/media/usb/uvc/uvc_video.c
> index e3567aeb0007..9f65cdbc1a1c 100644
> --- a/drivers/media/usb/uvc/uvc_video.c
> +++ b/drivers/media/usb/uvc/uvc_video.c
> @@ -1895,24 +1895,6 @@ static void uvc_video_stop_transfer(struct uvc_streaming *stream,
>  		uvc_free_urb_buffers(stream);
>  }
>  
> -/*
> - * Compute the maximum number of bytes per interval for an endpoint.
> - */
> -u16 uvc_endpoint_max_bpi(struct usb_device *dev, struct usb_host_endpoint *ep)
> -{
> -	u16 psize;
> -
> -	switch (dev->speed) {
> -	case USB_SPEED_SUPER:
> -	case USB_SPEED_SUPER_PLUS:
> -		return le16_to_cpu(ep->ss_ep_comp.wBytesPerInterval);
> -	default:
> -		psize = usb_endpoint_maxp(&ep->desc);
> -		psize *= usb_endpoint_maxp_mult(&ep->desc);
> -		return psize;
> -	}
> -}
> -
>  /*
>   * Initialize isochronous URBs and allocate transfer buffers. The packet size
>   * is given by the endpoint.
> @@ -1923,10 +1905,10 @@ static int uvc_init_video_isoc(struct uvc_streaming *stream,
>  	struct urb *urb;
>  	struct uvc_urb *uvc_urb;
>  	unsigned int npackets, i;
> -	u16 psize;
> +	u32 psize;
>  	u32 size;
>  
> -	psize = uvc_endpoint_max_bpi(stream->dev->udev, ep);
> +	psize = usb_endpoint_max_isoc_bpi(stream->dev->udev, ep);
>  	size = stream->ctrl.dwMaxVideoFrameSize;
>  
>  	npackets = uvc_alloc_urb_buffers(stream, size, psize, gfp_flags);
> @@ -2067,7 +2049,7 @@ static int uvc_video_start_transfer(struct uvc_streaming *stream,
>  				continue;
>  
>  			/* Check if the bandwidth is high enough. */
> -			psize = uvc_endpoint_max_bpi(stream->dev->udev, ep);
> +			psize = usb_endpoint_max_isoc_bpi(stream->dev->udev, ep);
>  			if (psize >= bandwidth && psize < best_psize) {
>  				altsetting = alts->desc.bAlternateSetting;
>  				best_psize = psize;
> diff --git a/drivers/media/usb/uvc/uvcvideo.h b/drivers/media/usb/uvc/uvcvideo.h
> index b9f8eb62ba1d..a77ba76e033a 100644
> --- a/drivers/media/usb/uvc/uvcvideo.h
> +++ b/drivers/media/usb/uvc/uvcvideo.h
> @@ -450,7 +450,7 @@ struct uvc_streaming {
>  
>  	struct usb_interface *intf;
>  	int intfnum;
> -	u16 maxpsize;
> +	u32 maxpsize;
>  
>  	struct uvc_streaming_header header;
>  	enum v4l2_buf_type type;
> @@ -818,8 +818,6 @@ void uvc_ctrl_cleanup_fh(struct uvc_fh *handle);
>  /* Utility functions */
>  struct usb_host_endpoint *uvc_find_endpoint(struct usb_host_interface *alts,
>  					    u8 epaddr);
> -u16 uvc_endpoint_max_bpi(struct usb_device *dev, struct usb_host_endpoint *ep);
> -
>  /* Quirks support */
>  void uvc_video_decode_isight(struct uvc_urb *uvc_urb,
>  			     struct uvc_buffer *buf,

-- 
Regards,

Laurent Pinchart

Re: [PATCH v2 3/4] USB: Add a function to obtain USB version independent maximum bpi value

[Hans de Goede]

Hi Sakari,

On 15-Jul-25 10:13 AM, Sakari Ailus wrote:
> Hi Hans,
> 
> Thank you for the review.
> 
> On Fri, Jul 11, 2025 at 03:44:21PM +0200, Hans de Goede wrote:
>> Hi Sarari,
>>
>> On 11-Jul-25 10:34 AM, Sakari Ailus wrote:
>>> From: "Rai, Amardeep" <amardeep.rai@intel.com>
>>>
>>> Add usb_endpoint_max_isoc_bpi() to obtain maximum bytes per interval for
>>> isochronous endpoints in a USB version independent way.
>>
>> Nice, thank you for adding a generic helper for this.
>>
>>> Signed-off-by: Rai, Amardeep <amardeep.rai@intel.com>
>>> Signed-off-by: Mathias Nyman <mathias.nyman@linux.intel.com>
>>> Co-developed-by: Sakari Ailus <sakari.ailus@linux.intel.com>
>>> Signed-off-by: Sakari Ailus <sakari.ailus@linux.intel.com>
>>> ---
>>>  include/linux/usb.h | 22 ++++++++++++++++++++++
>>>  1 file changed, 22 insertions(+)
>>>
>>> diff --git a/include/linux/usb.h b/include/linux/usb.h
>>> index 68166718ab30..bd70bd5ca82d 100644
>>> --- a/include/linux/usb.h
>>> +++ b/include/linux/usb.h
>>> @@ -2038,6 +2038,28 @@ static inline int usb_translate_errors(int error_code)
>>>  	}
>>>  }
>>>  
>>> +static inline u32 usb_endpoint_max_isoc_bpi(struct usb_device *dev,
>>> +					    const struct usb_host_endpoint *ep)
>>> +{
>>> +	if (usb_endpoint_type(&ep->desc) != USB_ENDPOINT_XFER_ISOC)
>>> +		return 0;
>>> +
>>> +	switch (dev->speed) {
>>> +	case USB_SPEED_SUPER_PLUS:
>>> +		if (USB_SS_SSP_ISOC_COMP(ep->ss_ep_comp.bmAttributes))
>>> +			return le32_to_cpu(ep->ssp_isoc_ep_comp.dwBytesPerInterval);
>>> +		fallthrough;
>>> +	case USB_SPEED_SUPER:
>>> +		return le16_to_cpu(ep->ss_ep_comp.wBytesPerInterval);
>>> +	case USB_SPEED_HIGH:
>>> +		if (!usb_endpoint_maxp(&ep->desc) && le16_to_cpu(dev->descriptor.bcdUSB) == 0x220)
>>> +			return le32_to_cpu(ep->eusb2_isoc_ep_comp.dwBytesPerInterval);
>>
>> Shouldn't there be a check here that ep->eusb2_isoc_ep_comp is filled?
>>
>> Like how the USB_SPEED_SUPER_PLU code above checks
>> USB_SS_SSP_ISOC_COMP(ep->ss_ep_comp.bmAttributes)?
>>
>> I know you check the bcdUSB, but in my experience that field sometimes
>> contains made up numbers, so I was wondering if there is an extra check
>> we can do here ?
> 
> In the case of eUSB2, there's no such flag as for the SuperSpeedPlus
> Isochronous Endpoint Companion. The eUSB2 Isochronous Endpoint Companion
> Descriptor is simply expected to be present on eUSB2 (bcdUSB check)
> isochronous IN endpoints that support more than 3KB per microframe.
> 
> Also what the USB_SS_SSP_ISOC_COMP() macro returns actually dependens on
> the device telling there's such a descriptor but it's still different from
> the device actually providing one. But what would you do if the device
> indicates it provides no SSP_ISOC_COMP descriptor but still does provide
> one?
> 
> How about adding a flag (or maybe a bit field?) to tell which endpoint
> descriptors have been actually filled in struct usb_host_endpoint? I might
> do that as a separate patch on top...

Adding a bit-field with which endpoint descriptors have actually
been filled sounds like a good idea.

I also agree with doing that as a follow-up patch and moving forward with
this patch as is, so:

Reviewed-by: Hans de Goede <hansg@kernel.org>

Regards,

Hans

Re: [PATCH v2 3/4] USB: Add a function to obtain USB version independent maximum bpi value

[Sakari Ailus]

Hi Hans,

On Wed, Jul 16, 2025 at 06:35:24PM +0200, Hans de Goede wrote:
> Hi Sakari,
> 
> On 15-Jul-25 10:13 AM, Sakari Ailus wrote:
> > Hi Hans,
> > 
> > Thank you for the review.
> > 
> > On Fri, Jul 11, 2025 at 03:44:21PM +0200, Hans de Goede wrote:
> >> Hi Sarari,
> >>
> >> On 11-Jul-25 10:34 AM, Sakari Ailus wrote:
> >>> From: "Rai, Amardeep" <amardeep.rai@intel.com>
> >>>
> >>> Add usb_endpoint_max_isoc_bpi() to obtain maximum bytes per interval for
> >>> isochronous endpoints in a USB version independent way.
> >>
> >> Nice, thank you for adding a generic helper for this.
> >>
> >>> Signed-off-by: Rai, Amardeep <amardeep.rai@intel.com>
> >>> Signed-off-by: Mathias Nyman <mathias.nyman@linux.intel.com>
> >>> Co-developed-by: Sakari Ailus <sakari.ailus@linux.intel.com>
> >>> Signed-off-by: Sakari Ailus <sakari.ailus@linux.intel.com>
> >>> ---
> >>>  include/linux/usb.h | 22 ++++++++++++++++++++++
> >>>  1 file changed, 22 insertions(+)
> >>>
> >>> diff --git a/include/linux/usb.h b/include/linux/usb.h
> >>> index 68166718ab30..bd70bd5ca82d 100644
> >>> --- a/include/linux/usb.h
> >>> +++ b/include/linux/usb.h
> >>> @@ -2038,6 +2038,28 @@ static inline int usb_translate_errors(int error_code)
> >>>  	}
> >>>  }
> >>>  
> >>> +static inline u32 usb_endpoint_max_isoc_bpi(struct usb_device *dev,
> >>> +					    const struct usb_host_endpoint *ep)
> >>> +{
> >>> +	if (usb_endpoint_type(&ep->desc) != USB_ENDPOINT_XFER_ISOC)
> >>> +		return 0;
> >>> +
> >>> +	switch (dev->speed) {
> >>> +	case USB_SPEED_SUPER_PLUS:
> >>> +		if (USB_SS_SSP_ISOC_COMP(ep->ss_ep_comp.bmAttributes))
> >>> +			return le32_to_cpu(ep->ssp_isoc_ep_comp.dwBytesPerInterval);
> >>> +		fallthrough;
> >>> +	case USB_SPEED_SUPER:
> >>> +		return le16_to_cpu(ep->ss_ep_comp.wBytesPerInterval);
> >>> +	case USB_SPEED_HIGH:
> >>> +		if (!usb_endpoint_maxp(&ep->desc) && le16_to_cpu(dev->descriptor.bcdUSB) == 0x220)
> >>> +			return le32_to_cpu(ep->eusb2_isoc_ep_comp.dwBytesPerInterval);
> >>
> >> Shouldn't there be a check here that ep->eusb2_isoc_ep_comp is filled?
> >>
> >> Like how the USB_SPEED_SUPER_PLU code above checks
> >> USB_SS_SSP_ISOC_COMP(ep->ss_ep_comp.bmAttributes)?
> >>
> >> I know you check the bcdUSB, but in my experience that field sometimes
> >> contains made up numbers, so I was wondering if there is an extra check
> >> we can do here ?
> > 
> > In the case of eUSB2, there's no such flag as for the SuperSpeedPlus
> > Isochronous Endpoint Companion. The eUSB2 Isochronous Endpoint Companion
> > Descriptor is simply expected to be present on eUSB2 (bcdUSB check)
> > isochronous IN endpoints that support more than 3KB per microframe.
> > 
> > Also what the USB_SS_SSP_ISOC_COMP() macro returns actually dependens on
> > the device telling there's such a descriptor but it's still different from
> > the device actually providing one. But what would you do if the device
> > indicates it provides no SSP_ISOC_COMP descriptor but still does provide
> > one?
> > 
> > How about adding a flag (or maybe a bit field?) to tell which endpoint
> > descriptors have been actually filled in struct usb_host_endpoint? I might
> > do that as a separate patch on top...
> 
> Adding a bit-field with which endpoint descriptors have actually
> been filled sounds like a good idea.
> 
> I also agree with doing that as a follow-up patch and moving forward with
> this patch as is, so:
> 
> Reviewed-by: Hans de Goede <hansg@kernel.org>

Thanks.

The descriptors appear to already have bDescriptorType field which can tell
the same -- it's non-zero for the valid ones. I think I'll use that instead
of adding new ones.

-- 
Regards,

Sakari Ailus

Re: [PATCH v2 4/4] media: uvcvideo: eUSB2 double isochronous bandwidth support

[Sakari Ailus]

Hi Laurent,

On Tue, Jul 15, 2025 at 12:10:32PM +0300, Laurent Pinchart wrote:
> Hi Sakari, Tao,
> 
> Thank you for the patch.
> 
> On Fri, Jul 11, 2025 at 11:34:13AM +0300, Sakari Ailus wrote:
> > From: Tao Q Tao <tao.q.tao@intel.com>
> > 
> > Use usb_endpoint_max_isoc_bpi() from the USB framework to find the maximum
> > bytes per interval for the endpoint. Consequently this adds eUSB2
> > isochronous mode and SuperSpeedPlus Isochronous Endpoint Compaion support
> > where larger bpi values are possible.
> > 
> > Co-developed-by: Amardeep Rai <amardeep.rai@intel.com>
> > Signed-off-by: Amardeep Rai <amardeep.rai@intel.com>
> > Signed-off-by: Tao Q Tao <tao.q.tao@intel.com>
> > Signed-off-by: Mathias Nyman <mathias.nyman@linux.intel.com>
> > Co-developed-by: Sakari Ailus <sakari.ailus@linux.intel.com>
> > Signed-off-by: Sakari Ailus <sakari.ailus@linux.intel.com>
> > Reviewed-by: Ilpo Järvinen <ilpo.jarvinen@linux.intel.com>
> 
> Assuming usb_endpoint_max_isoc_bpi() works correctly :-),
> 
> Reviewed-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>

Thank you!

> 
> I won't queue this patch for the time being as it depends on the rest of
> the series. Please let me know if I should queue it at a later point, or
> if you would like to merge it through the linux-usb tree. We would need
> to make sure there's no conflict with other scheduled patches for that
> kernel development cycle.

I think we'd prefer to go through the linux-usb tree, it seems like the
simplest way to get these to the same kernel release. The changes aren't
very big either.

Are you aware of UVC patches that might conflict with this one?

-- 
Kind regards,

Sakari Ailus