drm/i915: rework reading pipe disable fuses
This prepares to have possibly more than 3 pipes. I didn't want to
continue the previous approach since the check for "are the disabled
pipes the last ones" poses a combinatory explosion. We need that check
because in several places of the code we have that assumption. If that
ever becomes false in a new HW, other parts of the code would have to
change.
Now we start by considering we have info->num_pipes enabled and disable
each pipe that is marked as disabled. Then it's a simple matter of
checking if we have at least one pipe and that all the enabled ones are
the first pipes, i.e. there are no holes in the bitmask.
Cc: Jose Souza <jose.souza@intel.com>
Cc: Ville Syrjälä <ville.syrjala@linux.intel.com>
Signed-off-by: Lucas De Marchi <lucas.demarchi@intel.com>
Reviewed-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20190625175437.14840-3-lucas.demarchi@intel.com
diff --git a/drivers/gpu/drm/i915/intel_device_info.c b/drivers/gpu/drm/i915/intel_device_info.c
index 7135d8d..e64536e 100644
--- a/drivers/gpu/drm/i915/intel_device_info.c
+++ b/drivers/gpu/drm/i915/intel_device_info.c
@@ -929,35 +929,25 @@
}
} else if (HAS_DISPLAY(dev_priv) && INTEL_GEN(dev_priv) >= 9) {
u32 dfsm = I915_READ(SKL_DFSM);
- u8 disabled_mask = 0;
- bool invalid;
- int num_bits;
+ u8 enabled_mask = BIT(info->num_pipes) - 1;
if (dfsm & SKL_DFSM_PIPE_A_DISABLE)
- disabled_mask |= BIT(PIPE_A);
+ enabled_mask &= ~BIT(PIPE_A);
if (dfsm & SKL_DFSM_PIPE_B_DISABLE)
- disabled_mask |= BIT(PIPE_B);
+ enabled_mask &= ~BIT(PIPE_B);
if (dfsm & SKL_DFSM_PIPE_C_DISABLE)
- disabled_mask |= BIT(PIPE_C);
+ enabled_mask &= ~BIT(PIPE_C);
- num_bits = hweight8(disabled_mask);
-
- switch (disabled_mask) {
- case BIT(PIPE_A):
- case BIT(PIPE_B):
- case BIT(PIPE_A) | BIT(PIPE_B):
- case BIT(PIPE_A) | BIT(PIPE_C):
- invalid = true;
- break;
- default:
- invalid = false;
- }
-
- if (num_bits > info->num_pipes || invalid)
- DRM_ERROR("invalid pipe fuse configuration: 0x%x\n",
- disabled_mask);
+ /*
+ * At least one pipe should be enabled and if there are
+ * disabled pipes, they should be the last ones, with no holes
+ * in the mask.
+ */
+ if (enabled_mask == 0 || !is_power_of_2(enabled_mask + 1))
+ DRM_ERROR("invalid pipe fuse configuration: enabled_mask=0x%x\n",
+ enabled_mask);
else
- info->num_pipes -= num_bits;
+ info->num_pipes = hweight8(enabled_mask);
}
/* Initialize slice/subslice/EU info */
