usb: gadget: introduce support for sg lists
Some controllers support scatter/gather transfers
and that might be very useful for some gadget drivers.
This means that we can make use of larger buffer
allocations which means we will have less completion
IRQs overtime, thus improving the perceived performance.
Signed-off-by: Felipe Balbi <balbi@ti.com>
diff --git a/include/linux/usb/gadget.h b/include/linux/usb/gadget.h
index 4d99805..da653b5 100644
--- a/include/linux/usb/gadget.h
+++ b/include/linux/usb/gadget.h
@@ -20,6 +20,7 @@
#include <linux/init.h>
#include <linux/list.h>
#include <linux/slab.h>
+#include <linux/scatterlist.h>
#include <linux/types.h>
#include <linux/usb/ch9.h>
@@ -32,6 +33,9 @@
* @dma: DMA address corresponding to 'buf'. If you don't set this
* field, and the usb controller needs one, it is responsible
* for mapping and unmapping the buffer.
+ * @sg: a scatterlist for SG-capable controllers.
+ * @num_sgs: number of SG entries
+ * @num_mapped_sgs: number of SG entries mapped to DMA (internal)
* @length: Length of that data
* @stream_id: The stream id, when USB3.0 bulk streams are being used
* @no_interrupt: If true, hints that no completion irq is needed.
@@ -88,6 +92,10 @@
unsigned length;
dma_addr_t dma;
+ struct scatterlist *sg;
+ unsigned num_sgs;
+ unsigned num_mapped_sgs;
+
unsigned stream_id:16;
unsigned no_interrupt:1;
unsigned zero:1;
@@ -479,6 +487,7 @@
* @speed: Speed of current connection to USB host.
* @max_speed: Maximal speed the UDC can handle. UDC must support this
* and all slower speeds.
+ * @sg_supported: true if we can handle scatter-gather
* @is_otg: True if the USB device port uses a Mini-AB jack, so that the
* gadget driver must provide a USB OTG descriptor.
* @is_a_peripheral: False unless is_otg, the "A" end of a USB cable
@@ -519,6 +528,7 @@
struct list_head ep_list; /* of usb_ep */
enum usb_device_speed speed;
enum usb_device_speed max_speed;
+ unsigned sg_supported:1;
unsigned is_otg:1;
unsigned is_a_peripheral:1;
unsigned b_hnp_enable:1;