Re: [PATCH 4/8] pinctrl: qcom: sdm845: Provide ACPI support

Bjorn Andersson
2019-06-05T19:06:19Z

On Wed 05 Jun 00:31 PDT 2019, Lee Jones wrote:

> On Tue, 04 Jun 2019, Bjorn Andersson wrote:
>
> > On Tue 04 Jun 03:44 PDT 2019, Lee Jones wrote:
> >
> > > This patch provides basic support for booting with ACPI instead
> > > of the currently supported Device Tree. When doing so there are a
> > > couple of differences which we need to taken into consideration.
> > >
> > > Firstly, the SDM850 ACPI tables omit information pertaining to the
> > > 4 reserved GPIOs on the platform. If Linux attempts to touch/
> > > initialise any of these lines, the firmware will restart the
> > > platform.
> > >
> > > Secondly, when booting with ACPI, it is expected that the firmware
> > > will set-up things like; Regulators, Clocks, Pin Functions, etc in
> > > their ideal configuration. Thus, the possible Pin Functions
> > > available to this platform are not advertised when providing the
> > > higher GPIOD/Pinctrl APIs with pin information.
> > >
> > > Signed-off-by: Lee Jones <lee.jones@linaro.org>
> > > ---
> > > drivers/pinctrl/qcom/Kconfig | 2 +-
> > > drivers/pinctrl/qcom/pinctrl-sdm845.c | 35 ++++++++++++++++++++++++++-
> > > 2 files changed, 35 insertions(+), 2 deletions(-)
> > >
> > > diff --git a/drivers/pinctrl/qcom/Kconfig b/drivers/pinctrl/qcom/Kconfig
> > > index 2e66ab72c10b..aafbe932424f 100644
> > > --- a/drivers/pinctrl/qcom/Kconfig
> > > +++ b/drivers/pinctrl/qcom/Kconfig
> > > @@ -168,7 +168,7 @@ config PINCTRL_SDM660
> > >
> > > config PINCTRL_SDM845
> > > tristate "Qualcomm Technologies Inc SDM845 pin controller driver"
> > > - depends on GPIOLIB && OF
> > > + depends on GPIOLIB && (OF || ACPI)
> > > select PINCTRL_MSM
> > > help
> > > This is the pinctrl, pinmux, pinconf and gpiolib driver for the
> > > diff --git a/drivers/pinctrl/qcom/pinctrl-sdm845.c b/drivers/pinctrl/qcom/pinctrl-sdm845.c
> > > index c97f20fca5fd..7188bee3cf3e 100644
> > > --- a/drivers/pinctrl/qcom/pinctrl-sdm845.c
> > > +++ b/drivers/pinctrl/qcom/pinctrl-sdm845.c
> > > @@ -3,6 +3,7 @@
> > > * Copyright (c) 2016-2018, The Linux Foundation. All rights reserved.
> > > */
> > >
> > > +#include <linux/acpi.h>
> > > #include <linux/module.h>
> > > #include <linux/of.h>
> > > #include <linux/platform_device.h>
> > > @@ -1277,6 +1278,10 @@ static const struct msm_pingroup sdm845_groups[] = {
> > > UFS_RESET(ufs_reset, 0x99f000),
> > > };
> > >
> > > +static const int sdm845_acpi_reserved_gpios[] = {
> > > + 0, 1, 2, 3, 81, 82, 83, 84, -1
> > > +};
> > > +
> > > static const struct msm_pinctrl_soc_data sdm845_pinctrl = {
> > > .pins = sdm845_pins,
> > > .npins = ARRAY_SIZE(sdm845_pins),
> > > @@ -1284,14 +1289,41 @@ static const struct msm_pinctrl_soc_data sdm845_pinctrl = {
> > > .nfunctions = ARRAY_SIZE(sdm845_functions),
> > > .groups = sdm845_groups,
> > > .ngroups = ARRAY_SIZE(sdm845_groups),
> > > + .reserved_gpios = sdm845_acpi_reserved_gpios,
> >
> > The reason why put these in DT is because the list is board/firmware
> > dependent. E.g. the firmware on db845c does not support the peripherals
> > that sits on these 8 pins and as such these are not reserved.
>
> If we need to be more particular about which platform(s) this affects,
> we could add matching based on their differences (some ACPI HID or F/W
> version/descriptor, etc) as and when we enable them for booting with
> ACPI.
>

You're making an assumption that all SDM845 (the platform) devices using
ACPI will have this list of GPIOs reserved for secure firmware to use,
this is questionable but I don't have any better suggestion.

But you do this by adding a new struct msm_pinctrl_soc_data
sdm845_acpi_pinctrl, specifically for the ACPI case. And then, on the
line I object to here, you add this list as the list of reserved GPIOs
for the DT case as well.

> > But given that the two structs looks identical now, did you perhaps not
> > intend to add.reserved_gpios for the non-ACPI case?
>
> Given your example above, I think it's best that we let the
> configuration tables advertise these in the first instance. I only
> add them here because it is not possible to obtain them from
> elsewhere.
>

Then add it for ACPI only - which I still presume you intended to do by
adding sdm845_acpi_pinctrl (which is now identical to sdm845_pinctrl).

Regards,
Bjorn