[Intel-gfx] [RFC PATCH 3/9] drm/i915/spi: add driver for on-die spi device

[Lucas De Marchi]

On Thu, Feb 18, 2021 at 10:06:08PM -0800, Winkler, Tomas wrote:
>
>>
>> On Wed, Feb 17, 2021 at 08:58:12PM +0000, Winkler, Tomas wrote:
>> >>
>> >> On Tue, 16 Feb 2021, Tomas Winkler <tomas.winkler at intel.com> wrote:
>> >> > Add the platform driver for i915 on-die spi device, exposed via mfd
>> >> > framework.
>> >> >
>> >> > Cc: Rodrigo Vivi <rodrigo.vivi at intel.com>
>> >> > Cc: Lucas De Marchi <lucas.demarchi at intel.com>
>> >> > Signed-off-by: Tomas Winkler <tomas.winkler at intel.com>
>> >> > ---
>> >> >  drivers/gpu/drm/i915/Kconfig             |   2 +
>> >> >  drivers/gpu/drm/i915/Makefile            |   3 +
>> >> >  drivers/gpu/drm/i915/spi/intel_spi_drv.c | 116
>> >> > +++++++++++++++++++++++
>> >> >  3 files changed, 121 insertions(+)  create mode 100644
>> >> > drivers/gpu/drm/i915/spi/intel_spi_drv.c
>> >> >
>> >> > diff --git a/drivers/gpu/drm/i915/Kconfig
>> >> > b/drivers/gpu/drm/i915/Kconfig index abcaa8da45ac..13c870e5878e
>> >> > 100644
>> >> > --- a/drivers/gpu/drm/i915/Kconfig
>> >> > +++ b/drivers/gpu/drm/i915/Kconfig
>> >> > @@ -27,6 +27,8 @@ config DRM_I915
>> >> >  	select CEC_CORE if CEC_NOTIFIER
>> >> >  	select VMAP_PFN
>> >> >  	select MFD_CORE
>> >> > +	select MTD
>> >>
>> >> Selecting MTD does not seem to be a popular thing to do, which is
>> >> usually a clue it's probably the wrong thing to do.
>> >Depends, if it is not selected you'll end with wrongly configured system.
>>
>> no. I believe the idea is that having a CONFIG_I915_SPI, you could do
>>
>> 	depends on MTD
>>
>> like the other drivers doing similar thing:
>>
>> 	git grep MTD -- ':(exclude)drivers/mtd' ':(exclude)arch/' '*Kconfig'
> I know the pattern and it can be done, the issue is that mtd is used mostly in embedded systems so it is not selected by the desktop distros.
>The intel spi both on PCH and in GFX takes this into different direction and usage.

humn... but then we have a problem here. You're saying most of the
people won't need it because it's used only for manufacturing*.
And yet you want it to be force selected on everybody?  That
doesn't sound like a good plan.

Lucas De Marchi


* it may actually also be useful for kernel developers too, to dump its
content and validate the parser, help debug other systems, etc.

>
>Thanks
>Tomas
>