Re: A patch for a bug in adv748x

[Simon Yuan <Simon.Yuan@navico.com>]

On Tuesday, 12 September 2017 07:00:33 NZST Kieran Bingham wrote:
> Hi Simon,
> 
> On 11/09/17 05:30, Simon Yuan wrote:
> > Hi Niklas,
> > 
> > How are you doing? I've picked you as my contact since I met you earlier
> > this year at ELC2017. Not sure if you still remember, but we had a very
> > brief chat about the status of the adv748x driver.
> 
> I'll let Niklas reply to this bit :D
> 
> > Anyway, the real reason for this email is due to a bug I found in the
> > driver while integrating it into our product. I've attached a patch which
> > should be self explanatory. If you are the wrong person to contact, feel
> > free to forward this email to the right person, or let me know who I
> > should contact.
> Thanks for trying out the driver!
> 
> You're right, I think you have indeed found a bug - but I'm not certain the
> fix is correct...
> 
> Comment inline on the patch below...
> 
> > I've also made significant changes to the driver in order to satisfy our
> > video path requirements. We need to be able to dynamically switch between
> > HDMI/ composite input connected to TXA.
> > 
> > Is there a plan to make the current driver more flexible? The way I worked
> > around the current limitations is by introducing a media_entity for each
> > connector (e.g. HDMI and 18 types of analog input) physically connected to
> > the video decoder, and dynamically change the internal routing based on
> > the user selected connector linked to CP/SDP.
> 
> We did try to design the driver such that we could extend the flexibility
> later, but have pushed the driver upstream as the current version.
> 
> I hope to add CEC, and hotplug support later ... but I don't know when that
> work will be scheduled yet. - Of course - I'm happy to review patches :D
> > I'm not entirely satisfied with my workaround, so I won't embarrass myself
> > by sending a patch for the modified routing scheme.
> 
> I would be interested in seeing your implementation, feel free to send off
> lists if you prefer :D - I won't judge!
> 
> Regards
> 
> Kieran
> 
> > From 35eea62811d15c096341221c02abab3daadb9a19 Mon Sep 17 00:00:00 2001
> > From: Simon Yuan <simon.yuan@navico.com>
> > Date: Mon, 11 Sep 2017 16:07:40 +1200
> > Subject: [PATCH] media: i2c: adv748x: Map v4l2_std_id to the internal reg
> > 
> >  value
> > 
> > The video standard was not mapped to the corresponding value of the
> > internal video standard in adv748x_afe_querystd, causing the wrong
> > video standard to be selected.
> > ---
> > 
> >  drivers/media/i2c/adv748x/adv748x-afe.c | 7 ++++++-
> >  1 file changed, 6 insertions(+), 1 deletion(-)
> > 
> > diff --git a/drivers/media/i2c/adv748x/adv748x-afe.c
> > b/drivers/media/i2c/adv748x/adv748x-afe.c index
> > b33ccfc08708..9692e9ea2b70 100644
> > --- a/drivers/media/i2c/adv748x/adv748x-afe.c
> > +++ b/drivers/media/i2c/adv748x/adv748x-afe.c
> > @@ -217,6 +217,7 @@ static int adv748x_afe_querystd(struct v4l2_subdev
> > *sd, v4l2_std_id *std)> 
> >  {
> >  
> >  	struct adv748x_afe *afe = adv748x_sd_to_afe(sd);
> >  	struct adv748x_state *state = adv748x_afe_to_state(afe);
> > 
> > +	int afe_std;
> > 
> >  	int ret;
> >  	
> >  	mutex_lock(&state->mutex);
> > 
> > @@ -235,8 +236,12 @@ static int adv748x_afe_querystd(struct v4l2_subdev
> > *sd, v4l2_std_id *std)> 
> >  	/* Read detected standard */
> >  	ret = adv748x_afe_status(afe, NULL, std);
> > 
> > +	afe_std = adv748x_afe_std(std);
> 
> I think this should get the afe_std for the afe->curr_norm. This function
> should leave the hardware in the configured state (not the detected state).
> 
> If you agree, I'll update the patch and send to the mailinglists for
> integration.
> > +	if (afe_std < 0)
> > +		goto unlock;
> > +
> > 
> >  	/* Restore original state */
> > 
> > -	adv748x_afe_set_video_standard(state, afe->curr_norm);
> > +	adv748x_afe_set_video_standard(state, afe_std);
> > 
> >  unlock:
> >  	mutex_unlock(&state->mutex);
> > 
> > Best regards,
> > Simon

Hi Kieran,

You are correct, I wasn't thinking straight. I've indeed introduced a bug 
within a bug :)

You are more than welcome to modify the patch and send it off for integration.

As for my implementation of the internal routing, I can certainly send it to 
you later once the implementation matures a bit.

Best regards,
Simon