[PATCH] drm/etnaviv: make THERMAL selectable

[Emil Velikov]

Hi Philipp,

On 1 December 2017 at 14:30, Philipp Zabel <p.zabel at pengutronix.de> wrote:
> Depending on THERMAL || !THERMAL caused a Kconfig dependency loop on
> x86_64:
>
>   drivers/gpu/drm/tve200/Kconfig:1:error: recursive dependency detected!
>   For a resolution refer to Documentation/kbuild/kconfig-language.txt
>   subsection "Kconfig recursive dependency limitations"
>   drivers/gpu/drm/tve200/Kconfig:1:       symbol DRM_TVE200 depends on CMA
>   For a resolution refer to Documentation/kbuild/kconfig-language.txt
>   subsection "Kconfig recursive dependency limitations"
>   mm/Kconfig:489: symbol CMA is selected by DRM_ETNAVIV
>   For a resolution refer to Documentation/kbuild/kconfig-language.txt
>   subsection "Kconfig recursive dependency limitations"
>   drivers/gpu/drm/etnaviv/Kconfig:2:      symbol DRM_ETNAVIV depends on THERMAL
>   For a resolution refer to Documentation/kbuild/kconfig-language.txt
>   subsection "Kconfig recursive dependency limitations"
>   drivers/thermal/Kconfig:5:      symbol THERMAL is selected by ACPI_VIDEO
>   For a resolution refer to Documentation/kbuild/kconfig-language.txt
>   subsection "Kconfig recursive dependency limitations"
>   drivers/acpi/Kconfig:189:       symbol ACPI_VIDEO is selected by BACKLIGHT_CLASS_DEVICE
>   For a resolution refer to Documentation/kbuild/kconfig-language.txt
>   subsection "Kconfig recursive dependency limitations"
>   drivers/video/backlight/Kconfig:158:    symbol BACKLIGHT_CLASS_DEVICE is selected by DRM_PARADE_PS8622
>   For a resolution refer to Documentation/kbuild/kconfig-language.txt
>   subsection "Kconfig recursive dependency limitations"
>   drivers/gpu/drm/bridge/Kconfig:62:      symbol DRM_PARADE_PS8622 depends on DRM_BRIDGE
>   For a resolution refer to Documentation/kbuild/kconfig-language.txt
>   subsection "Kconfig recursive dependency limitations"
>   drivers/gpu/drm/bridge/Kconfig:1:       symbol DRM_BRIDGE is selected by DRM_TVE200
>
> To work around this, add a new option to make DRM_ETNAVIV select THERMAL
> instead.
>
> Reported-by: Stephen Rothwell <sfr at canb.auug.org.au>
> Fixes: dba536cd9538 ("drm/etnaviv: add THERMAL dependency")
> Signed-off-by: Philipp Zabel <p.zabel at pengutronix.de>
> ---
>  drivers/gpu/drm/etnaviv/Kconfig       | 11 ++++++++++-
>  drivers/gpu/drm/etnaviv/etnaviv_gpu.c | 12 +++++++++---
>  2 files changed, 19 insertions(+), 4 deletions(-)
>
> diff --git a/drivers/gpu/drm/etnaviv/Kconfig b/drivers/gpu/drm/etnaviv/Kconfig
> index bbf2828ca5768..c446e867b3a24 100644
> --- a/drivers/gpu/drm/etnaviv/Kconfig
> +++ b/drivers/gpu/drm/etnaviv/Kconfig
> @@ -4,9 +4,9 @@ config DRM_ETNAVIV
>         depends on DRM
>         depends on ARCH_MXC || ARCH_DOVE || (ARM && COMPILE_TEST)
>         depends on MMU
> -       depends on THERMAL || !THERMAL # if THERMAL=m, this can't be 'y'
>         select SHMEM
>         select SYNC_FILE
> +       select THERMAL if DRM_ETNAVIV_THERMAL
>         select TMPFS
>         select WANT_DEV_COREDUMP
>         select CMA if HAVE_DMA_CONTIGUOUS
> @@ -14,6 +14,15 @@ config DRM_ETNAVIV
>         help
>           DRM driver for Vivante GPUs.
>
> +config DRM_ETNAVIV_THERMAL
> +       bool "enable ETNAVIV thermal throttling"
> +       depends on DRM_ETNAVIV
> +       default y
> +       select THERMAL
Just a quick braindump, while waiting for coffee to kick-in:

Having a separate toggle sounds cool, but yet select(ing) THERMAL, a
user visible option, seems like an abuse.
One should swap the select with the original depends line.
  depends on THERMAL || !THERMAL # if THERMAL=m, this can't be 'y'

That doesn't help with the original circular dependency, yet it seems
that ACPI is also abusing THERMAL.
If one swaps the "select THERMAL" with depends... while guarding the
respective code behind IS_ENABLED things should work like a charm.

HTH
Emil