[PATCH 04/16] pinctrl: samsung: Parse pin banks from DT
Tomasz Figa
t.figa at samsung.com
Wed Oct 10 04:39:30 EDT 2012
On Wednesday 10 of October 2012 09:34:05 Linus Walleij wrote:
> On Mon, Oct 8, 2012 at 10:39 AM, Tomasz Figa <t.figa at samsung.com> wrote:
> > Currently SoC-specific properties such as list of pin banks, register
> > offsets and bitfield sizes are being taken from static data structures
> > residing in pinctrl-exynos.c.
> >
> > This patch modifies the pinctrl-samsung driver to parse all
> > SoC-specific
> > data from device tree, which will allow to remove the static data
> > structures and facilitate adding of further SoC variants to the
> > pinctrl-samsung driver.
>
> So why? Two approaches:
>
> - Put as much info as possible into the device tree
> - Put as much info as possible into the driver
>
> The first approach is currently only used by pinctrl-single.c.
>
> That driver is designed for the case where all info about
> the hardware arrives in some description language that
> can be translated into a simple DT description.
>
> If you want to use that approach, you should use that
> driver. If that driver does not work for you, then it's not
> fulfilling it's purpose as a one-stop shop for simple
> pin controllers entirely contained within the device tree,
> and should be renamed or redesigned.
>
> If you will end up with a hybrid approach with some
> stuff in the device tree and some stuff in the code,
> it's better to keep the old driver.
This will allow us to cover all the existing Samsung SoCs, starting from
S3C24xx, through S3C64xx, S5P*, all supported Exynos SoCs and ending on any
future SoCs using this kind of pin controller, without bloating the driver
with hardly readable macros, lots of (often duplicated) static data and
similar.
If there are some serious problems with this approach, just let me know and
I will reconsider it, but if not, I'd like to keep it, because of the
benefits it gives.
(Even if I moved all those SoC-specific data to static structures located
in the driver, to keep the most readable way of GPIO specification in DT, I
would have to create nodes for all banks in DT anyway and the driver would
have to match particular nodes with their static data. I don't like this
kind of approach.)
Best regards,
--
Tomasz Figa
Samsung Poland R&D Center
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