usb: gadget: f_uvc: disallow the CPU to enter deeper sleep when streamon

I test on RK3399 IND EVB running Android R system, and
set the USB gadget as UVC function via configfs, both
the USB 2.0 and 3.0 UVC have preview abnormal problems.
If the CPU enter deeper sleep, the USB DMA transfer gets
corrupted, and the UVC ISOC transmission lost data.

This patch puts in a "pm_qos_latency" requirement which
will keep the CPU out of the deeper sleep states when
UVC stream on. And allow the CPU to enter deeper sleep
state after UVC stream off.

Change-Id: I808290f124c6a32da3888819348093a205bfad61
Signed-off-by: William Wu <william.wu@rock-chips.com>

Author: wuliangfeng

drivers/usb/gadget/function/f_uvc.c

@@ -1112,6 +1112,7 @@ static struct usb_function_instance *uvc_alloc_inst(void)
 
 	opts->streaming_interval = 1;
 	opts->streaming_maxpacket = 1024;
+	opts->pm_qos_latency = 0;
 
 	ret = uvcg_attach_configfs(opts);
 	if (ret < 0) {

drivers/usb/gadget/function/u_uvc.h

@@ -87,6 +87,7 @@ struct f_uvc_opts {
 	 */
 	struct mutex			lock;
 	int				refcnt;
+	int				pm_qos_latency;
 };
 
 #endif /* U_UVC_H */

drivers/usb/gadget/function/uvc.h

@@ -18,6 +18,7 @@
 #include <linux/spinlock.h>
 #include <linux/usb/composite.h>
 #include <linux/videodev2.h>
+#include <linux/pm_qos.h>
 
 #include <media/v4l2-device.h>
 #include <media/v4l2-dev.h>
@@ -119,6 +120,8 @@ struct uvc_device {
 	enum uvc_state state;
 	struct usb_function func;
 	struct uvc_video video;
+	/* for creating and issuing QoS requests */
+	struct pm_qos_request pm_qos;
 
 	/* Descriptors */
 	struct {

drivers/usb/gadget/function/uvc_configfs.c

@@ -14,6 +14,7 @@
  */
 
 #include <linux/sort.h>
+#include <linux/pm_qos.h>
 
 #include "u_uvc.h"
 #include "uvc_configfs.h"
@@ -2768,6 +2769,7 @@ UVCG_OPTS_ATTR(streaming_bulk, streaming_bulk, 1);
 UVCG_OPTS_ATTR(streaming_interval, streaming_interval, 16);
 UVCG_OPTS_ATTR(streaming_maxpacket, streaming_maxpacket, 3072);
 UVCG_OPTS_ATTR(streaming_maxburst, streaming_maxburst, 15);
+UVCG_OPTS_ATTR(pm_qos_latency, pm_qos_latency, PM_QOS_LATENCY_ANY);
 
 #undef UVCG_OPTS_ATTR
 
@@ -2776,6 +2778,7 @@ static struct configfs_attribute *uvc_attrs[] = {
 	&f_uvc_opts_attr_streaming_interval,
 	&f_uvc_opts_attr_streaming_maxpacket,
 	&f_uvc_opts_attr_streaming_maxburst,
+	&f_uvc_opts_attr_pm_qos_latency,
 	NULL,
 };
 

drivers/usb/gadget/function/uvc_video.c

@@ -16,12 +16,14 @@
 #include <linux/usb/ch9.h>
 #include <linux/usb/gadget.h>
 #include <linux/usb/video.h>
+#include <linux/pm_qos.h>
 
 #include <media/v4l2-dev.h>
 
 #include "uvc.h"
 #include "uvc_queue.h"
 #include "uvc_video.h"
+#include "u_uvc.h"
 
 /* --------------------------------------------------------------------------
  * Video codecs
@@ -365,23 +367,32 @@ int uvcg_video_enable(struct uvc_video *video, int enable)
 {
 	unsigned int i;
 	int ret;
+	struct uvc_device *uvc;
+	struct f_uvc_opts *opts;
 
 	if (video->ep == NULL) {
 		uvcg_info(&video->uvc->func,
 			  "Video enable failed, device is uninitialized.\n");
 		return -ENODEV;
 	}
 
+	uvc = container_of(video, struct uvc_device, video);
+	opts = fi_to_f_uvc_opts(uvc->func.fi);
+
 	if (!enable) {
 		for (i = 0; i < UVC_NUM_REQUESTS; ++i)
 			if (video->req[i])
 				usb_ep_dequeue(video->ep, video->req[i]);
 
 		uvc_video_free_requests(video);
 		uvcg_queue_enable(&video->queue, 0);
+		if (pm_qos_request_active(&uvc->pm_qos))
+			pm_qos_remove_request(&uvc->pm_qos);
 		return 0;
 	}
 
+	pm_qos_add_request(&uvc->pm_qos, PM_QOS_CPU_DMA_LATENCY,
+			   opts->pm_qos_latency);
 	if ((ret = uvcg_queue_enable(&video->queue, 1)) < 0)
 		return ret;
 

drivers/usb/gadget/legacy/webcam.c

@@ -386,6 +386,7 @@ webcam_bind(struct usb_composite_dev *cdev)
 	uvc_opts->fs_streaming = uvc_fs_streaming_cls;
 	uvc_opts->hs_streaming = uvc_hs_streaming_cls;
 	uvc_opts->ss_streaming = uvc_ss_streaming_cls;
+	uvc_opts->pm_qos_latency = 0;
 
 	/* Allocate string descriptor numbers ... note that string contents
 	 * can be overridden by the composite_dev glue.