Quoting Yunwei Zhang (2018-03-19 21:50:07)
> WaProgramMgsrForCorrectSliceSpecificMmioReads dictate that before any MMIO
> read into Slice/Subslice specific registers, MCR packet control
> register(0xFDC) needs to be programmed to point to any enabled
> slice/subslice pair. Otherwise, incorrect value will be returned.
>
> However, that means each subsequent MMIO read will be forwarded to a
> specific slice/subslice combination as read is unicast. This is OK since
> slice/subslice specific register values are consistent in almost all cases
> across slice/subslice. There are rare occasions such as INSTDONE that this
> value will be dependent on slice/subslice combo, in such cases, we need to
> program 0xFDC and recover this after. This is already covered by
> read_subslice_reg for INSTDONE.
>
> Also, 0xFDC will lose its information after TDR/engine reset/power state
> change.
>
> Signed-off-by: Yunwei Zhang <yunwei.zhang@xxxxxxxxx>
> Cc: Oscar Mateo <oscar.mateo@xxxxxxxxx>
> Cc: Michel Thierry <michel.thierry@xxxxxxxxx>
> Cc: Joonas Lahtinen <joonas.lahtinen@xxxxxxxxxxxxxxx>
> ---
> drivers/gpu/drm/i915/intel_engine_cs.c | 43 ++++++++++++++++++++++++++++++++--
> 1 file changed, 41 insertions(+), 2 deletions(-)
>
> diff --git a/drivers/gpu/drm/i915/intel_engine_cs.c b/drivers/gpu/drm/i915/intel_engine_cs.c
> index a2b1e9e..bc8fed7 100644
> --- a/drivers/gpu/drm/i915/intel_engine_cs.c
> +++ b/drivers/gpu/drm/i915/intel_engine_cs.c
> @@ -781,6 +781,29 @@ const char *i915_cache_level_str(struct drm_i915_private *i915, int type)
> }
> }
>
> +static u32 calculate_mcr(u32 mcr, struct drm_i915_private *dev_priv)
> +{
> + const struct sseu_dev_info *sseu = &(INTEL_INFO(dev_priv)->sseu);
INTEL_SSEU(dev_priv);
> + u32 slice = find_last_bit((unsigned long *)&(sseu->slice_mask),
> + sizeof(sseu->slice_mask));
> + u32 subslice = find_last_bit((unsigned long *)&(sseu->subslice_mask[slice]),
> + sizeof(sseu->subslice_mask[0]));
You seem to have mispelt fls().
Or send a patch to convert find_last_bit() into fls() for known small
sizes.
-Chris
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