On Mon, Sep 13, 2021 at 10:42:54AM -0700, Radhakrishna Sripada wrote:
> Earlier while calculating derated bw we would use 90% of the calculated
> bw. Starting ADL-P we use a non standard derating. Updating the formulae
> to reflect the same.
>
> Bspec: 64631
>
> Fixes: 4d32fe2f14a7 ("drm/i915/adl_p: Update memory bandwidth parameters")
> Cc: Matt Roper <matthew.d.roper@xxxxxxxxx>
> Signed-off-by: Radhakrishna Sripada <radhakrishna.sripada@xxxxxxxxx>
> ---
> drivers/gpu/drm/i915/display/intel_bw.c | 8 ++++++--
> 1 file changed, 6 insertions(+), 2 deletions(-)
>
> diff --git a/drivers/gpu/drm/i915/display/intel_bw.c b/drivers/gpu/drm/i915/display/intel_bw.c
> index e91e0e0191fb..23121ddd2580 100644
> --- a/drivers/gpu/drm/i915/display/intel_bw.c
> +++ b/drivers/gpu/drm/i915/display/intel_bw.c
> @@ -222,31 +222,35 @@ static int icl_sagv_max_dclk(const struct intel_qgv_info *qi)
>
> struct intel_sa_info {
> u16 displayrtids;
> - u8 deburst, deprogbwlimit;
> + u8 deburst, deprogbwlimit, derating;
> };
>
> static const struct intel_sa_info icl_sa_info = {
> .deburst = 8,
> .deprogbwlimit = 25, /* GB/s */
> .displayrtids = 128,
> + .derating = 10,
> };
>
> static const struct intel_sa_info tgl_sa_info = {
> .deburst = 16,
> .deprogbwlimit = 34, /* GB/s */
> .displayrtids = 256,
> + .derating = 10,
> };
>
> static const struct intel_sa_info rkl_sa_info = {
> .deburst = 16,
> .deprogbwlimit = 20, /* GB/s */
> .displayrtids = 128,
> + .derating = 10,
> };
>
> static const struct intel_sa_info adls_sa_info = {
> .deburst = 16,
> .deprogbwlimit = 38, /* GB/s */
> .displayrtids = 256,
> + .derating = 20,
This is changing the derating for both ADL-S and ADL-P, but the bspec
says that ADL-S still uses a derating of 10.
Matt
> };
>
> static int icl_get_bw_info(struct drm_i915_private *dev_priv, const struct intel_sa_info *sa)
> @@ -302,7 +306,7 @@ static int icl_get_bw_info(struct drm_i915_private *dev_priv, const struct intel
> bw = icl_calc_bw(sp->dclk, clpchgroup * 32 * num_channels, ct);
>
> bi->deratedbw[j] = min(maxdebw,
> - bw * 9 / 10); /* 90% */
> + bw * (100 - sa->derating) / 100);
>
> drm_dbg_kms(&dev_priv->drm,
> "BW%d / QGV %d: num_planes=%d deratedbw=%u\n",
> --
> 2.20.1
>
--
Matt Roper
Graphics Software Engineer
VTT-OSGC Platform Enablement
Intel Corporation
(916) 356-2795
