[PATCH] media: fix au0828 dvb suspend/resume to call dvb_frontend_suspend/resume

[PATCH] media: fix au0828 dvb suspend/resume to call dvb_frontend_suspend/resume

[Shuah Khan]

au0828 doesn't resume correctly and TV tuning fails with
xc_set_signal_source(0) failed message. Change au0828 dvb
suspend and resume interfaces to suspend and resume frontend
during suspend and resume respectively. au0828_dvb_suspend()
calls dvb_frontend_suspend() which in turn invokes tuner ops
sleep followed by fe ops sleep. au0828_dvb_resume() calls
dvb_frontend_resume() which in turn calls fe ops ini follwed
by tuner ops ini before waking up the frontend. With this change
HVR950Q suspend and resume work when system gets suspended when
digital function is tuned to a channel and with active TV stream,
and after resume it went right back to active TV stream.

Signed-off-by: Shuah Khan <shuah.kh@samsung.com>
---
 drivers/media/usb/au0828/au0828-dvb.c |   37 ++++++++++++++-------------------
 1 file changed, 16 insertions(+), 21 deletions(-)

diff --git a/drivers/media/usb/au0828/au0828-dvb.c b/drivers/media/usb/au0828/au0828-dvb.c
index 821f86e..50e7c82 100644
--- a/drivers/media/usb/au0828/au0828-dvb.c
+++ b/drivers/media/usb/au0828/au0828-dvb.c
@@ -619,35 +619,30 @@ int au0828_dvb_register(struct au0828_dev *dev)
 
 void au0828_dvb_suspend(struct au0828_dev *dev)
 {
-	struct au0828_dvb *dvb = &dev->dvb;
-
-	if (dvb->frontend && dev->urb_streaming) {
-		pr_info("stopping DVB\n");
+	struct au0828_dvb *dvb;
+	int rc;
 
-		cancel_work_sync(&dev->restart_streaming);
+	if (dev == NULL)
+		return;
 
-		/* Stop transport */
-		mutex_lock(&dvb->lock);
-		stop_urb_transfer(dev);
-		au0828_stop_transport(dev, 1);
-		mutex_unlock(&dvb->lock);
-		dev->need_urb_start = 1;
+	dvb = &dev->dvb;
+	if (dvb->frontend) {
+		rc = dvb_frontend_suspend(dvb->frontend);
+		pr_info("au0828_dvb_suspend(): Suspending DVB fe %d\n", rc);
 	}
 }
 
 void au0828_dvb_resume(struct au0828_dev *dev)
 {
-	struct au0828_dvb *dvb = &dev->dvb;
-
-	if (dvb->frontend && dev->need_urb_start) {
-		pr_info("resuming DVB\n");
+	struct au0828_dvb *dvb;
+	int rc;
 
-		au0828_set_frontend(dvb->frontend);
+	if (dev == NULL)
+		return;
 
-		/* Start transport */
-		mutex_lock(&dvb->lock);
-		au0828_start_transport(dev);
-		start_urb_transfer(dev);
-		mutex_unlock(&dvb->lock);
+	dvb = &dev->dvb;
+	if (dvb->frontend) {
+		rc = dvb_frontend_resume(dvb->frontend);
+		pr_info("au0828_dvb_resume(): Resuming DVB fe %d\n", rc);
 	}
 }
-- 
1.7.10.4

Re: [PATCH] media: fix au0828 dvb suspend/resume to call dvb_frontend_suspend/resume

[Mauro Carvalho Chehab]

Hi Shuah,

Em Mon, 11 Aug 2014 21:13:55 -0600
Shuah Khan <shuah.kh@samsung.com> escreveu:

> au0828 doesn't resume correctly and TV tuning fails with
> xc_set_signal_source(0) failed message. Change au0828 dvb
> suspend and resume interfaces to suspend and resume frontend
> during suspend and resume respectively. au0828_dvb_suspend()
> calls dvb_frontend_suspend() which in turn invokes tuner ops
> sleep followed by fe ops sleep. au0828_dvb_resume() calls
> dvb_frontend_resume() which in turn calls fe ops ini follwed
> by tuner ops ini before waking up the frontend. With this change
> HVR950Q suspend and resume work when system gets suspended when
> digital function is tuned to a channel and with active TV stream,
> and after resume it went right back to active TV stream.
> 
> Signed-off-by: Shuah Khan <shuah.kh@samsung.com>
> ---
>  drivers/media/usb/au0828/au0828-dvb.c |   37 ++++++++++++++-------------------
>  1 file changed, 16 insertions(+), 21 deletions(-)
> 
> diff --git a/drivers/media/usb/au0828/au0828-dvb.c b/drivers/media/usb/au0828/au0828-dvb.c
> index 821f86e..50e7c82 100644
> --- a/drivers/media/usb/au0828/au0828-dvb.c
> +++ b/drivers/media/usb/au0828/au0828-dvb.c
> @@ -619,35 +619,30 @@ int au0828_dvb_register(struct au0828_dev *dev)
>  
>  void au0828_dvb_suspend(struct au0828_dev *dev)
>  {
> -	struct au0828_dvb *dvb = &dev->dvb;
> -
> -	if (dvb->frontend && dev->urb_streaming) {
> -		pr_info("stopping DVB\n");
> +	struct au0828_dvb *dvb;
> +	int rc;
>  
> -		cancel_work_sync(&dev->restart_streaming);

The restart streaming delayed work still needs to be canceled if
active. This work can be active while DVB is streaming, to workaround
on a chipset bug.

The best is to first call cancel the pending URBs and stop_urb_transfer(),
in order to avoid race conditions.

> +	if (dev == NULL)
> +		return;

In this specific device driver, I think that this condition will never
happen:

	$ git grep "dev = NULL" drivers/media/usb/au0828/au0828*
	drivers/media/usb/au0828/au0828-core.c: dev->usbdev = NULL;

>  
> -		/* Stop transport */
> -		mutex_lock(&dvb->lock);
> -		stop_urb_transfer(dev);

My understanding is that we still need to cancel the pending URBs before
suspending, in order to stop the DMA engine.

> -		au0828_stop_transport(dev, 1);
> -		mutex_unlock(&dvb->lock);
> -		dev->need_urb_start = 1;
> +	dvb = &dev->dvb;
> +	if (dvb->frontend) {
> +		rc = dvb_frontend_suspend(dvb->frontend);
> +		pr_info("au0828_dvb_suspend(): Suspending DVB fe %d\n", rc);
>  	}
>  }
>  
>  void au0828_dvb_resume(struct au0828_dev *dev)
>  {
> -	struct au0828_dvb *dvb = &dev->dvb;
> -
> -	if (dvb->frontend && dev->need_urb_start) {
> -		pr_info("resuming DVB\n");
> +	struct au0828_dvb *dvb;
> +	int rc;
>  
> -		au0828_set_frontend(dvb->frontend);
> +	if (dev == NULL)
> +		return;
>  
> -		/* Start transport */
> -		mutex_lock(&dvb->lock);
> -		au0828_start_transport(dev);
> -		start_urb_transfer(dev);
> -		mutex_unlock(&dvb->lock);

As we need to stop pending URB transfers and stop the DMA engine,
we still need the above code. We don't need to restart a pending
work, because what the pending work would be doing is to stop and
restart the transfer, and the suspend/resume code should do it already.

> +	dvb = &dev->dvb;
> +	if (dvb->frontend) {
> +		rc = dvb_frontend_resume(dvb->frontend);
> +		pr_info("au0828_dvb_resume(): Resuming DVB fe %d\n", rc);
>  	}
>  }

Regards,
Mauro