[Intel-gfx] [RFC 0/2] Add new CDCLK step for RPL-U

[Borah, Chaitanya Kumar]

> -----Original Message-----
> From: Roper, Matthew D <matthew.d.roper at intel.com>
> Sent: Tuesday, February 28, 2023 6:06 AM
> To: Borah, Chaitanya Kumar <chaitanya.kumar.borah at intel.com>
> Cc: intel-gfx at lists.freedesktop.org; jani.nikula at linux.intel.com; Shankar,
> Uma <uma.shankar at intel.com>; Syrjala, Ville <ville.syrjala at intel.com>;
> Srivatsa, Anusha <anusha.srivatsa at intel.com>; Atwood, Matthew S
> <matthew.s.atwood at intel.com>
> Subject: Re: [RFC 0/2] Add new CDCLK step for RPL-U
> 
> On Mon, Jan 30, 2023 at 03:38:04PM +0530, Chaitanya Kumar Borah wrote:
> > A new step of 480MHz has been added on SKUs that have an RPL-U device
> > id. This particular step is to support 120Hz panels more efficiently.
> >
> > This patchset adds a new table to include this new CDCLK step. Details
> > can be found in BSpec entry 55409.
> 
> Hi Chaitanya.  It looks like we probably need one more change related to the
> 480MHz rate beyond what was in this series.  For platforms that support this
> rate, we can set voltage level 1 (see bspec 49208) whereas the i915 code at
> the moment will push it up to voltage level 2 instead.

Hello Matt,

Thank you for pointing it out. I will have a look and float a patch ASAP.

Regards

Chaitanya

> 
> 
> Matt
> 
> >
> > Create a new sub-platform to identify RPL-U which will enable us to
> > make the differentiation during CDCLK initialization.
> >
> > Furthermore, we need to make a distinction between ES (Engineering
> > Sample) and QS (Quality Sample) parts as this change comes only to QS
> > parts. This version of the patch does not include this change as we
> > are yet to make a decision if this particular part needs to be
> > upstreamed.(see comments on revision 2)
> >
> > Chaitanya Kumar Borah (2):
> >   drm/i915: Add RPL-U sub platform
> >   drm/i915/display: Add 480 MHz CDCLK steps for RPL-U
> >
> >  drivers/gpu/drm/i915/display/intel_cdclk.c | 26
> ++++++++++++++++++++++
> >  drivers/gpu/drm/i915/i915_drv.h            |  2 ++
> >  drivers/gpu/drm/i915/intel_device_info.c   |  7 ++++++
> >  drivers/gpu/drm/i915/intel_device_info.h   |  1 +
> >  include/drm/i915_pciids.h                  | 12 ++++++----
> >  5 files changed, 44 insertions(+), 4 deletions(-)
> >
> > --
> > 2.25.1
> >
> 
> --
> Matt Roper
> Graphics Software Engineer
> Linux GPU Platform Enablement
> Intel Corporation