drm/i915: Fix dbuf slice config lookup

Apparently I totally fumbled the loop condition when I
removed the ARRAY_SIZE() stuff from the dbuf slice config
lookup. Comparing the loop index with the active_pipes bitmask
is utter nonsense, what we want to do is check to see if the
mask is zero or not.

Note that the code actually ended up working correctly despite
the fumble, up until commit eef173954432 ("drm/i915: Allow
!join_mbus cases for adlp+ dbuf configuration") when things
broke for real.

Cc: stable@vger.kernel.org
Fixes: 05e8155afe35 ("drm/i915: Use a sentinel to terminate the dbuf slice arrays")
Signed-off-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20220207132700.481-1-ville.syrjala@linux.intel.com
Reviewed-by: Jani Nikula <jani.nikula@intel.com>

diff --git a/drivers/gpu/drm/i915/intel_pm.c b/drivers/gpu/drm/i915/intel_pm.c
index 02084652fe3daea61b4487883f120b7961bf00ff..da721aea70ff98444e05dbef85b3a487309eb330 100644 (file)
--- a/drivers/gpu/drm/i915/intel_pm.c
+++ b/drivers/gpu/drm/i915/intel_pm.c
@@ -4848,7 +4848,7 @@ static u8 compute_dbuf_slices(enum pipe pipe, u8 active_pipes, bool join_mbus,
 {
        int i;
 
-       for (i = 0; i < dbuf_slices[i].active_pipes; i++) {
+       for (i = 0; dbuf_slices[i].active_pipes != 0; i++) {
                if (dbuf_slices[i].active_pipes == active_pipes &&
                    dbuf_slices[i].join_mbus == join_mbus)
                        return dbuf_slices[i].dbuf_mask[pipe];