Re: [PATCH v5 14/20] pinctrl: samsung: Add gs101 SoC pinctrl configuration

[Peter Griffin <peter.griffin@linaro.org>]

Hi Krzysztof / Sam,

On Wed, 6 Dec 2023 at 11:38, Krzysztof Kozlowski
<krzysztof.kozlowski@linaro.org> wrote:
>
> On 02/12/2023 02:36, Alim Akhtar wrote:
> >
> >>
> >> On Fri, Dec 1, 2023 at 10:11 AM Peter Griffin <peter.griffin@linaro.org>
> >> wrote:
> >>>
> >>> Add support for the pin-controller found on the gs101 SoC used in
> >>> Pixel 6 phones.
> >>>
> >>> Signed-off-by: Peter Griffin <peter.griffin@linaro.org>
> >>> ---
> >>>  .../pinctrl/samsung/pinctrl-exynos-arm64.c    | 159 ++++++++++++++++++
> >>>  drivers/pinctrl/samsung/pinctrl-exynos.c      |   2 +
> >>>  drivers/pinctrl/samsung/pinctrl-exynos.h      |  34 ++++
> >>>  drivers/pinctrl/samsung/pinctrl-samsung.c     |   2 +
> >>>  drivers/pinctrl/samsung/pinctrl-samsung.h     |   1 +
> >>>  5 files changed, 198 insertions(+)
> >>>
> >>> diff --git a/drivers/pinctrl/samsung/pinctrl-exynos-arm64.c
> >>> b/drivers/pinctrl/samsung/pinctrl-exynos-arm64.c
> >>> index cb965cf93705..e1a0668ecb16 100644
> >>> --- a/drivers/pinctrl/samsung/pinctrl-exynos-arm64.c
> >>> +++ b/drivers/pinctrl/samsung/pinctrl-exynos-arm64.c
> >>> @@ -796,3 +796,162 @@ const struct samsung_pinctrl_of_match_data
> >> fsd_of_data __initconst = {
> >>>         .ctrl           = fsd_pin_ctrl,
> >>>         .num_ctrl       = ARRAY_SIZE(fsd_pin_ctrl),
> >>>  };
> >>> +
> >>> +/*
> >>> + * bank type for non-alive type
> >>> + * (CON bit field: 4, DAT bit field: 1, PUD bit field: 4, DRV bit
> >>> +field: 4)
> >>> + * (CONPDN bit field: 2, PUDPDN bit field: 4)  */ static struct
> >>> +samsung_pin_bank_type gs101_bank_type_off  = {
> >>> +       .fld_width = { 4, 1, 4, 4, 2, 4, },
> >>> +       .reg_offset = { 0x00, 0x04, 0x08, 0x0c, 0x10, 0x14, }, };
> >>
> >> This is just the same as exynos850_bank_type_off (100% duplication).
> >> Here is what I suggest. Now that it's obvious there is some common platform
> >> for moder Exynos SoCs, and it's probably Exynos9, I'd suggest next course of
> >> action (if maintainers agree):
> >>   1. Remove this one
> >>   2. Rename exynos850_bank_type_off to exynos9_bank_type_off
> >>   3. Use it for both gs101 and exynos850
> >>
> >> Does it make sense?
> >>
> > My opinion is to reuse exynos850 for gs101 (wherever applicable), same philosophy was historically followed in this file.
> > That way (using exynos850 for gs101) things will be simple.
> > Adding exynos9_* is not adding any benefit, rather it create confusion.
>
> I don't see much value in renaming exynos850 bank type to exynos9
> considering:
> 1. We don't really know the bank types for all of Exynos9xxx SoCs,
> 2. Exynos7885 also uses Exynos850 bank types. Exynos7885 was much
> earlier than Exynos9xxx family.

Thanks Alim and Krzysztof for your input.

Exynos7885 (Exynos 8 family) using Exynos850 bank types looks like a
mistake to me. I found some downstream code for 7885, and it doesn't
look like selecting a filter was supported downstream [1] [2]. As Sam
confirmed this hardware is present on e850 downstream, so 7885 and
e850 have different hardware at least for these banks.

As the EXYNOS850_PIN_BANK_EINTW macro is being used by Exynos850,
exynosautov9 and exynos7885 using a generic macro with gs101 doesn't
look possible (I have no way to find out these filter register
offsets, or if those platforms actually have these registers).

Therefore I propose:
1. For bank types that match exactly use exynos850 versions
2. For bank types which have fltcon_offset we add a new macro
EXYNOS9_PIN_BANK_EINTW like it exists in this series or
GS101_PIN_BANK_EINTW if people prefer that

That still leaves us in the rather unfortunate position that if
Exynos850 wants selectable filter support then it wouldn't be using
the EXYNOS850_PIN_BANK_EINTW macro. But I suggest we cross that bridge
if/when Sam decides to support selectable filters on e850. We could do
some sort of macro renaming, but what we rename it to though I have no
idea EXYNOS7885_blah or EXYNOSAUTOV9_blah.

@Chanho do you know if ExynosAutov9 supports selectable filters on alive banks?

regards,

Peter

[1] https://github.com/samsungexynos7885/android_kernel_samsung_universal7885/blob/android-9.0/drivers/pinctrl/samsung/pinctrl-exynos.c#L1696
[2] https://github.com/samsungexynos7885/android_kernel_samsung_universal7885/blob/android-9.0/drivers/pinctrl/samsung/pinctrl-exynos.h#L108