On Tuesday 29 March 2016 00:11:13, Stefan Agner wrote:
> >> --- a/Documentation/devicetree/bindings/display/fsl,dcu.txt
> >> +++ b/Documentation/devicetree/bindings/display/fsl,dcu.txt
> >>
> >> @@ -14,6 +14,7 @@ Required properties:
> >> Optional properties:
> >> - clocks: Second handle for pixel clock.
> >> - clock-names: Second name "pix" for pixel clock.
> >>
> >> +- fsl,tcon: The phandle to the timing controller node.
> >
> > Maybe a comment this is (currently) only for Vybrid, but not LS1021A.
>
> IMHO, such references to SoCs in a peripheral binding is somewhat
> misplaced. If we would start doing this, we would end up in lots of SoC
> references, and nobody knows whether they are actually accurate and up
> to date... And I think we should add tcon to LS1021a, more on that
> below...
Well, I don't mind after all.
> >> --- /dev/null
> >> +++ b/drivers/gpu/drm/fsl-dcu/fsl_tcon.c
> >> [...]
> >> +struct fsl_tcon *fsl_tcon_init(struct device *dev)
> >> +{
> >> + struct fsl_tcon *tcon;
> >> + struct device_node *np;
> >> + int ret;
> >> +
> >> + tcon = devm_kzalloc(dev, sizeof(*tcon), GFP_KERNEL);
> >> + if (!tcon)
> >> + return NULL;
> >> +
> >> + np = of_parse_phandle(dev->of_node, "fsl,tcon", 0);
> >> + if (!np) {
> >> + dev_warn(dev, "Couldn't find the tcon node\n");
> >> + return NULL;
> >> + }
> >
> > Maybe check for device tree node before allocating struct fsl_tcon? Also
> > this should not be a warning, as on LS1021A this is to be expected.
>
> Agreed, definitely the smarter sequence.
>
> Afact LS1021a has also a TCON. At least in Jianwei Wangs initial patches
> it was part of the driver, see:
> https://lkml.org/lkml/2015/7/13/242
>
> Not sure how that driver can work without TCON support on LS1021a, maybe
> the bootloader sets the TCON to bypass?
>
> Since I do not have a LS1021a, I hesitated to just add it to the LS1021s
> dt's, but it should be fairly straight forward.
Interesting, but in Patch 3 (https://lists.freedesktop.org/archives/dri-devel/2015-July/086381.html) no TCON node is added and using is still
optional. Yet, I don't find any TCON hardware in the LS1021A reference manual,
e.g. in the memory map. I hard guess is that it doesn't require/use one.
Without memory address it would be pretty hard to add one.
Alexander
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