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[PATCH v2 3/3] usb: gadget: f_sourcesink: Addition of SSP endpoint for ISOC transfers

Srikanth Chary Chennoju posted 3 patches 1 month ago
[PATCH v2 3/3] usb: gadget: f_sourcesink: Addition of SSP endpoint for ISOC transfers
Posted by Srikanth Chary Chennoju 1 month ago 
This patch is created to support super speed plus endpoint for Isoc
transfers. Now super speed endpoint companion is accompanied by super
speed plus endpoint companion. With this change we could see the Isoc IN
and OUT performance reaching to ~749MB/sec which is 96K per uframe.
The performance numbers are confirmed through Lecroy trace.

Signed-off-by: Srikanth Chary Chennoju <srikanth.chary-chennoju@amd.com>
---
 drivers/usb/gadget/function/f_sourcesink.c | 23 ++++++++++++++++++++--
 include/uapi/linux/usb/ch9.h               |  2 ++
 2 files changed, 23 insertions(+), 2 deletions(-)

diff --git a/drivers/usb/gadget/function/f_sourcesink.c b/drivers/usb/gadget/function/f_sourcesink.c
index a3a69166c343..79efb6295725 100644
--- a/drivers/usb/gadget/function/f_sourcesink.c
+++ b/drivers/usb/gadget/function/f_sourcesink.c
@@ -232,6 +232,12 @@ static struct usb_ss_ep_comp_descriptor ss_iso_source_comp_desc = {
 	.wBytesPerInterval =	cpu_to_le16(1024),
 };
 
+static struct usb_ssp_isoc_ep_comp_descriptor ssp_iso_source_comp_desc = {
+	.bLength =		USB_DT_SSP_ISOC_EP_COMP_SIZE,
+	.bDescriptorType =	USB_DT_SSP_ISOC_ENDPOINT_COMP,
+	.dwBytesPerInterval =	cpu_to_le32(1024),
+};
+
 static struct usb_endpoint_descriptor ss_iso_sink_desc = {
 	.bLength =		USB_DT_ENDPOINT_SIZE,
 	.bDescriptorType =	USB_DT_ENDPOINT,
@@ -250,6 +256,12 @@ static struct usb_ss_ep_comp_descriptor ss_iso_sink_comp_desc = {
 	.wBytesPerInterval =	cpu_to_le16(1024),
 };
 
+static struct usb_ssp_isoc_ep_comp_descriptor ssp_iso_sink_comp_desc = {
+	.bLength =		USB_DT_SSP_ISOC_EP_COMP_SIZE,
+	.bDescriptorType =	USB_DT_SSP_ISOC_ENDPOINT_COMP,
+	.dwBytesPerInterval =	cpu_to_le32(1024),
+};
+
 static struct usb_descriptor_header *ss_source_sink_descs[] = {
 	(struct usb_descriptor_header *) &source_sink_intf_alt0,
 	(struct usb_descriptor_header *) &ss_source_desc,
@@ -264,8 +276,10 @@ static struct usb_descriptor_header *ss_source_sink_descs[] = {
 	(struct usb_descriptor_header *) &ss_sink_comp_desc,
 	(struct usb_descriptor_header *) &ss_iso_source_desc,
 	(struct usb_descriptor_header *) &ss_iso_source_comp_desc,
+	(struct usb_descriptor_header *) &ssp_iso_source_comp_desc,
 	(struct usb_descriptor_header *) &ss_iso_sink_desc,
 	(struct usb_descriptor_header *) &ss_iso_sink_comp_desc,
+	(struct usb_descriptor_header *) &ssp_iso_sink_comp_desc,
 	NULL,
 };
 
@@ -423,7 +437,7 @@ sourcesink_bind(struct usb_configuration *c, struct usb_function *f)
 	 */
 	ss_iso_source_desc.wMaxPacketSize = ss->isoc_maxpacket;
 	ss_iso_source_desc.bInterval = ss->isoc_interval;
-	ss_iso_source_comp_desc.bmAttributes = ss->isoc_mult;
+	ss_iso_source_comp_desc.bmAttributes = USB_DT_SSP_ISOC_COMP | ss->isoc_mult;
 	ss_iso_source_comp_desc.bMaxBurst = ss->isoc_maxburst;
 	ss_iso_source_comp_desc.wBytesPerInterval = ss->isoc_maxpacket *
 		(ss->isoc_mult + 1) * (ss->isoc_maxburst + 1);
@@ -432,12 +446,17 @@ sourcesink_bind(struct usb_configuration *c, struct usb_function *f)
 
 	ss_iso_sink_desc.wMaxPacketSize = ss->isoc_maxpacket;
 	ss_iso_sink_desc.bInterval = ss->isoc_interval;
-	ss_iso_sink_comp_desc.bmAttributes = ss->isoc_mult;
+	ss_iso_sink_comp_desc.bmAttributes = USB_DT_SSP_ISOC_COMP | ss->isoc_mult;
 	ss_iso_sink_comp_desc.bMaxBurst = ss->isoc_maxburst;
 	ss_iso_sink_comp_desc.wBytesPerInterval = ss->isoc_maxpacket *
 		(ss->isoc_mult + 1) * (ss->isoc_maxburst + 1);
 	ss_iso_sink_desc.bEndpointAddress = fs_iso_sink_desc.bEndpointAddress;
 
+	ssp_iso_source_comp_desc.dwBytesPerInterval = ss->isoc_maxpacket *
+	  (ss->isoc_mult + 1) * (ss->isoc_maxburst + 1) * USB_LANE_SPEED_MANTISSA_GEN2_BY_GEN1;
+	ssp_iso_sink_comp_desc.dwBytesPerInterval = ss->isoc_maxpacket *
+	  (ss->isoc_mult + 1) * (ss->isoc_maxburst + 1) * USB_LANE_SPEED_MANTISSA_GEN2_BY_GEN1;
+
 	ret = usb_assign_descriptors(f, fs_source_sink_descs,
 			hs_source_sink_descs, ss_source_sink_descs,
 			ss_source_sink_descs);
diff --git a/include/uapi/linux/usb/ch9.h b/include/uapi/linux/usb/ch9.h
index 8003243a4937..22782c5cb2f3 100644
--- a/include/uapi/linux/usb/ch9.h
+++ b/include/uapi/linux/usb/ch9.h
@@ -702,6 +702,8 @@ struct usb_ssp_isoc_ep_comp_descriptor {
 } __attribute__ ((packed));
 
 #define USB_DT_SSP_ISOC_EP_COMP_SIZE		8
+#define USB_DT_SSP_ISOC_COMP			(1 << 7) /*support for SSP ISOC EP COMP*/
+#define USB_LANE_SPEED_MANTISSA_GEN2_BY_GEN1    2
 
 /*-------------------------------------------------------------------------*/
 
-- 
2.25.1
Re: [PATCH v2 3/3] usb: gadget: f_sourcesink: Addition of SSP endpoint for ISOC transfers
Posted by Thinh Nguyen 1 month ago 
On Thu, Aug 28, 2025, Srikanth Chary Chennoju wrote:
> This patch is created to support super speed plus endpoint for Isoc
> transfers. Now super speed endpoint companion is accompanied by super
> speed plus endpoint companion. With this change we could see the Isoc IN
> and OUT performance reaching to ~749MB/sec which is 96K per uframe.
> The performance numbers are confirmed through Lecroy trace.
> 
> Signed-off-by: Srikanth Chary Chennoju <srikanth.chary-chennoju@amd.com>
> ---
>  drivers/usb/gadget/function/f_sourcesink.c | 23 ++++++++++++++++++++--
>  include/uapi/linux/usb/ch9.h               |  2 ++
>  2 files changed, 23 insertions(+), 2 deletions(-)
> 
> diff --git a/drivers/usb/gadget/function/f_sourcesink.c b/drivers/usb/gadget/function/f_sourcesink.c
> index a3a69166c343..79efb6295725 100644
> --- a/drivers/usb/gadget/function/f_sourcesink.c
> +++ b/drivers/usb/gadget/function/f_sourcesink.c
> @@ -232,6 +232,12 @@ static struct usb_ss_ep_comp_descriptor ss_iso_source_comp_desc = {
>  	.wBytesPerInterval =	cpu_to_le16(1024),
>  };
>  
> +static struct usb_ssp_isoc_ep_comp_descriptor ssp_iso_source_comp_desc = {
> +	.bLength =		USB_DT_SSP_ISOC_EP_COMP_SIZE,
> +	.bDescriptorType =	USB_DT_SSP_ISOC_ENDPOINT_COMP,
> +	.dwBytesPerInterval =	cpu_to_le32(1024),

Why set the dwBytesPerInterval and wBytesPerInterval when they will be
overwritten on bind later?

> +};
> +
>  static struct usb_endpoint_descriptor ss_iso_sink_desc = {
>  	.bLength =		USB_DT_ENDPOINT_SIZE,
>  	.bDescriptorType =	USB_DT_ENDPOINT,
> @@ -250,6 +256,12 @@ static struct usb_ss_ep_comp_descriptor ss_iso_sink_comp_desc = {
>  	.wBytesPerInterval =	cpu_to_le16(1024),
>  };
>  
> +static struct usb_ssp_isoc_ep_comp_descriptor ssp_iso_sink_comp_desc = {
> +	.bLength =		USB_DT_SSP_ISOC_EP_COMP_SIZE,
> +	.bDescriptorType =	USB_DT_SSP_ISOC_ENDPOINT_COMP,
> +	.dwBytesPerInterval =	cpu_to_le32(1024),
> +};
> +
>  static struct usb_descriptor_header *ss_source_sink_descs[] = {
>  	(struct usb_descriptor_header *) &source_sink_intf_alt0,
>  	(struct usb_descriptor_header *) &ss_source_desc,
> @@ -264,8 +276,10 @@ static struct usb_descriptor_header *ss_source_sink_descs[] = {
>  	(struct usb_descriptor_header *) &ss_sink_comp_desc,
>  	(struct usb_descriptor_header *) &ss_iso_source_desc,
>  	(struct usb_descriptor_header *) &ss_iso_source_comp_desc,
> +	(struct usb_descriptor_header *) &ssp_iso_source_comp_desc,
>  	(struct usb_descriptor_header *) &ss_iso_sink_desc,
>  	(struct usb_descriptor_header *) &ss_iso_sink_comp_desc,
> +	(struct usb_descriptor_header *) &ssp_iso_sink_comp_desc,
>  	NULL,
>  };
>  
> @@ -423,7 +437,7 @@ sourcesink_bind(struct usb_configuration *c, struct usb_function *f)
>  	 */
>  	ss_iso_source_desc.wMaxPacketSize = ss->isoc_maxpacket;
>  	ss_iso_source_desc.bInterval = ss->isoc_interval;
> -	ss_iso_source_comp_desc.bmAttributes = ss->isoc_mult;
> +	ss_iso_source_comp_desc.bmAttributes = USB_DT_SSP_ISOC_COMP | ss->isoc_mult;
>  	ss_iso_source_comp_desc.bMaxBurst = ss->isoc_maxburst;
>  	ss_iso_source_comp_desc.wBytesPerInterval = ss->isoc_maxpacket *
>  		(ss->isoc_mult + 1) * (ss->isoc_maxburst + 1);
> @@ -432,12 +446,17 @@ sourcesink_bind(struct usb_configuration *c, struct usb_function *f)
>  
>  	ss_iso_sink_desc.wMaxPacketSize = ss->isoc_maxpacket;
>  	ss_iso_sink_desc.bInterval = ss->isoc_interval;
> -	ss_iso_sink_comp_desc.bmAttributes = ss->isoc_mult;
> +	ss_iso_sink_comp_desc.bmAttributes = USB_DT_SSP_ISOC_COMP | ss->isoc_mult;

Don't automatically set USB_DT_SSP_ISOC_COMP if deviec is not connected
in SSP. probably need to create a separate set of descriptors for SSP.

>  	ss_iso_sink_comp_desc.bMaxBurst = ss->isoc_maxburst;
>  	ss_iso_sink_comp_desc.wBytesPerInterval = ss->isoc_maxpacket *
>  		(ss->isoc_mult + 1) * (ss->isoc_maxburst + 1);
>  	ss_iso_sink_desc.bEndpointAddress = fs_iso_sink_desc.bEndpointAddress;
>  
> +	ssp_iso_source_comp_desc.dwBytesPerInterval = ss->isoc_maxpacket *
> +	  (ss->isoc_mult + 1) * (ss->isoc_maxburst + 1) * USB_LANE_SPEED_MANTISSA_GEN2_BY_GEN1;
> +	ssp_iso_sink_comp_desc.dwBytesPerInterval = ss->isoc_maxpacket *
> +	  (ss->isoc_mult + 1) * (ss->isoc_maxburst + 1) * USB_LANE_SPEED_MANTISSA_GEN2_BY_GEN1;
> +

Missing cpu_to_le* endian conversions.

>  	ret = usb_assign_descriptors(f, fs_source_sink_descs,
>  			hs_source_sink_descs, ss_source_sink_descs,
>  			ss_source_sink_descs);
> diff --git a/include/uapi/linux/usb/ch9.h b/include/uapi/linux/usb/ch9.h
> index 8003243a4937..22782c5cb2f3 100644
> --- a/include/uapi/linux/usb/ch9.h
> +++ b/include/uapi/linux/usb/ch9.h
> @@ -702,6 +702,8 @@ struct usb_ssp_isoc_ep_comp_descriptor {
>  } __attribute__ ((packed));
>  
>  #define USB_DT_SSP_ISOC_EP_COMP_SIZE		8
> +#define USB_DT_SSP_ISOC_COMP			(1 << 7) /*support for SSP ISOC EP COMP*/

Put this under bmAttributes

> +#define USB_LANE_SPEED_MANTISSA_GEN2_BY_GEN1    2

There's no GEN2_BY_GEN1. There's Gen2x1. Also lane speed mantissa is not
2 for Gen2x1. What you probably wanted to put is probably gen value
multiply by lane count?

BR,
Thinh

>  
>  /*-------------------------------------------------------------------------*/
>  
> -- 
> 2.25.1
> 

BR,
Thinh

Patchew 2.1-devel-b67e4c2

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