[PATCH v3 2/2] ARM: EXYNOS: Add Gscaler device from DT

[Kukjin Kim]

Sylwester Nawrocki wrote:
> 
> On 08/01/2012 09:48 AM, Thomas Abraham wrote:
> > On 1 August 2012 12:10, Kukjin Kim <kgene.kim at samsung.com> wrote:
> >> Shaik Ameer Basha wrote:
> >
> > [...]
> >
> >>> +* Samsung Exynos5 Gscaler device
> >>> +
> >>> +Gscaler is used for scaling and color space conversion on EXYNOS5
> SoCs.
> >>> +
> >>> +Required properties:
> >>> +- compatible: should be "samsung,exynos5250-gsc"
> >>
> >> IMO, should be "samsung,exynos5-gsc" because upcoming EXYNOS5 SoCs can
> use
> >> same gscaler driver.
> 
> In addition to the below explanation, perhaps it's obvious, but the driver
> can claim compatibility with multiple devices, i.e. match with multiple
> 'compatible' properties.
> 

The name of exact model is 'gscaler' for EXYNOS5 SoCs not only for
EXYNOS5250. So the driver which has been submitted is also 'exynos-gsc' not
'exynos5250-gsc'. Note that there is no gscaler on EXYNOS4 SoCs now, it can
be either 'exynos5-gsc' or 'exynos-gsc'. In addition, since some
peripherals/drivers can be used for multiple SoCs and actually it does, I'm
still thinking the compatible should be represent its usage. I don't know
why restricted name is much clearer. And if multiple 'compatible' is
required, we can add it later.

Thanks.

Best regards,
Kgene.
--
Kukjin Kim <kgene.kim at samsung.com>, Senior Engineer,
SW Solution Development Team, Samsung Electronics Co., Ltd.

> 
> > The compatible string should always be specific and it should clearly
> > identify the type of the controller. If there are other variants of
> > the GSC controller in previous of upcoming SoC's, then those
> > controllers will have a different compatible value.
> >
> > This allows device drivers to know the type of the controller and
> > handle the differences among them. And, the node in the dts/dtsi file
> > should always claim compatibility to the base version of the
> > controller that the platform supports.
> >
> > So the compatible value "samsung,exynos5250-gsc" is right one. If a
> > new SoC in the Exynos5 family has the same GSC controller as that in
> > Exynos5250 (no difference at all), then GSC device node in its dts
> > file can continue to claim compatibility to Exynos5250 type. The
> > "samsung,s3c2410-wdt is an example of this case which has been used on
> > all Samsung SoC's .
> >