Re: [RFC][PATCH] drm: adv7511/33: Fix adv7511_cec_init() failure handling

[Archit Taneja]

On 11/29/2017 03:02 AM, John Stultz wrote:
> On Sun, Nov 26, 2017 at 4:56 AM, Archit Taneja <architt@xxxxxxxxxxxxxx> wrote:
> > On 11/17/2017 04:29 AM, John Stultz wrote:
> > > diff --git a/drivers/gpu/drm/bridge/adv7511/adv7511_drv.c
> > > b/drivers/gpu/drm/bridge/adv7511/adv7511_drv.c
> > > index 0e14f15..939c3b9 100644
> > > --- a/drivers/gpu/drm/bridge/adv7511/adv7511_drv.c
> > > +++ b/drivers/gpu/drm/bridge/adv7511/adv7511_drv.c
> > > @@ -1203,12 +1203,12 @@ static int adv7511_probe(struct i2c_client *i2c,
> > > const struct i2c_device_id *id)
> > >      #ifdef CONFIG_DRM_I2C_ADV7511_CEC
> > >          ret = adv7511_cec_init(dev, adv7511, offset);
> > > -       if (ret)
> > > -               goto err_unregister_cec;
> > >    #else
> > > -       regmap_write(adv7511->regmap, ADV7511_REG_CEC_CTRL + offset,
> > > -                    ADV7511_CEC_CTRL_POWER_DOWN);
> > > +       ret = 1;
> > >    #endif
> > > +       if (ret)
> > > +               regmap_write(adv7511->regmap, ADV7511_REG_CEC_CTRL +
> > > offset,
> > > +                            ADV7511_CEC_CTRL_POWER_DOWN);
> >
> >
> > This would force CEC to be powered off even if adv7511_cec_init() returned
> > 0, right?
>
> I don't think so. The initent was its only powered off if
> adv7511_cec_init returns an error or if  CONFIG_DRM_I2C_ADV7511_CEC is
> not set.
>
> > Do we know why the call to adv7511_cec_init() is failing on the Hikey board?
> > If it's
> > because there isn't a "cec" clock specified in DT, it's not really a fatal
> > error, it
> > just means that the platform hasn't been set up to support CEC. In that
>
> Yea. I believe this is the case w/ HiKey.  I don't have deeply
> detailed docs on the board so I'm not sure if we will be able to
> enable that or not (Xinliang/Guodong: Do you know if its possible?).
> In the meantime though, we shouldn't regress.
>
> > case, we
> > should just power down the CEC block. So, if adv7511_cec_init() would return
> > a
> > -ENOENT, which we could use as a hint to power down CEC. So, maybe something
> > like this?:
> >
> > #ifdef CONFIG_DRM_I2C_ADV7511_CEC
> >          ret = adv7511_cec_init(dev, adv7511, offset);
> >          if (ret && ret != -ENOENT)
> >                  goto err_unregister_cec;
> > #endif
> >          if (ret)
> >              regmap_write(adv7511->regmap, ADV7511_REG_CEC_CTRL + offset,
> >                          ADV7511_CEC_CTRL_POWER_DOWN);
> >
> > Apart from this, we should also move adv7511_cec_init() up in the probe so
> > that
> > it's called before the drm_bridge is registered.
>
> Hans has since reworked the patch w/ a new version. You might want to
> check his patches and see if they fit what your imagining.

Yes, I saw Hans's patch after I wrote to you. That patch looks perfect. I'll
queue that to the drm-misc repo once it's rebased on 4.15-rc1.

Thanks,
Archit

> thanks
> -john

--
Qualcomm Innovation Center, Inc. is a member of Code Aurora Forum,
a Linux Foundation Collaborative Project