Re: [PATCH V7 6/6] backlight: qcom-wled: Add auto string detection logic

[kgunda]

On 2019-10-17 19:00, Lee Jones wrote:
> On Thu, 17 Oct 2019, kgunda@xxxxxxxxxxxxxx wrote:
>
> > On 2019-10-17 17:56, Lee Jones wrote:
> > > On Wed, 16 Oct 2019, Kiran Gunda wrote:
> > >
> > > > The auto string detection algorithm checks if the current WLED
> > > > sink configuration is valid. It tries enabling every sink and
> > > > checks if the OVP fault is observed. Based on this information
> > > > it detects and enables the valid sink configuration.
> > > > Auto calibration will be triggered when the OVP fault interrupts
> > > > are seen frequently thereby it tries to fix the sink configuration.
> > > >
> > > > The auto-detection also kicks in when the connected LED string
> > > > of the display-backlight malfunctions (because of damage) and
> > > > requires the damaged string to be turned off to prevent the
> > > > complete panel and/or board from being damaged.
> > > >
> > > > Signed-off-by: Kiran Gunda <kgunda@xxxxxxxxxxxxxx>
> > > > ---
> > > >  drivers/video/backlight/qcom-wled.c | 410
> > > > +++++++++++++++++++++++++++++++++++-
> > > >  1 file changed, 404 insertions(+), 6 deletions(-)
> > > >
> > > > diff --git a/drivers/video/backlight/qcom-wled.c
> > > > b/drivers/video/backlight/qcom-wled.c
> > > > index b5b125c..ff7c409 100644
> > > > --- a/drivers/video/backlight/qcom-wled.c
> > > > +++ b/drivers/video/backlight/qcom-wled.c
>
> [...]
>
> > > > +		if (int_sts & WLED3_CTRL_REG_OVP_FAULT_STATUS)
> > > > +			dev_dbg(wled->dev, "WLED OVP fault detected with SINK %d\n",
> > > > +				i + 1);
> > >
> > > I haven't reviewed the whole patch, but this caught my eye.
> > >
> > > I think this should be upgraded to dev_warn().
> > >
> > Thought of keeping these messages silent, Because the string 
> > configuration
> > will be corrected in this
> > and informing it at end of the auto string detection.
>
> [...]
>
> > > > +	} else {
> > > > +		dev_warn(wled->dev, "New WLED string configuration found %x\n",
> > > > +			 sink_valid);
> > >
> > > Why would the user care about this?  Is it not normal?
> > >
> > Actually, it comes here if the user provided string configuration in 
> > the
> > device tree is in-correct.
> > That's why just informing the user about the right string 
> > configuration,
> > after the auto string detection.
>
> Then I think we need to be more forthcoming.  Tell the user the
> configuration is incorrect and what you've done to rectify it.
>
> "XXX is not a valid configuration - using YYY instead"
Sure. Will update it in the next series.
> [...]
>
> > > > +static int wled_configure_ovp_irq(struct wled *wled,
> > > > +				  struct platform_device *pdev)
> > > > +{
> > > > +	int rc;
> > > > +	u32 val;
> > > > +
> > > > +	wled->ovp_irq = platform_get_irq_byname(pdev, "ovp");
> > > > +	if (wled->ovp_irq < 0) {
> > > > +		dev_dbg(&pdev->dev, "ovp irq is not used\n");
> > >
> > > I assume this is optional.  What happens if no IRQ is provided?
> > >
> > Here OVP IRQ is used to detect the wrong string detection. If it is 
> > not
> > provided the auto string detection logic won't work.
>
> "OVP IRQ not found - disabling automatic string detection"
Sure. Will update it in the next series.
> > > If, for instance, polling mode is enabled, maybe something like this
> > > would be better?
> > >
> > >       dev_warn(&pdev->dev, "No IRQ found, falling back to polling
> > > mode\n");