[PATCH] drm/msm/a6xx: fall back to MX when gmxc.lvl has no levels

[Tyler Baker <tyler.baker@oss.qualcomm.com>]

Eliza's command DB has a gmxc.lvl entry with an all-zero level table,
though Eliza does not use a GMxC rail. a6xx_gmu_rpmh_votes_init() picks
any gmxc.lvl entry as the GX secondary rail, so building the GX votes
fails, a6xx_gmu_init() ignores the error and the GMU gets a zeroed GX
vote table. On the A722 the first GX_BW_PERF_VOTE HFI then times out
and the GPU stops responding. Before a6xx_gmu_rpmh_read_arc() began
trimming trailing zero levels, every GX vote silently used level 0.

Read gmxc.lvl with a6xx_gmu_rpmh_read_arc(), which rejects an entry
without levels, so the GX votes fall back to mx.lvl.

Fixes: b5269bf0e1ad ("drm/msm/a6xx: Factor out RPMh arc-vote helpers")
Signed-off-by: Tyler Baker <tyler.baker@oss.qualcomm.com>
---
 drivers/gpu/drm/msm/adreno/a6xx_gmu.c | 5 +++--
 1 file changed, 3 insertions(+), 2 deletions(-)

diff --git a/drivers/gpu/drm/msm/adreno/a6xx_gmu.c b/drivers/gpu/drm/msm/adreno/a6xx_gmu.c
index 662f09bec9d52..c42e0d4fb946d 100644
--- a/drivers/gpu/drm/msm/adreno/a6xx_gmu.c
+++ b/drivers/gpu/drm/msm/adreno/a6xx_gmu.c
@@ -1887,15 +1887,16 @@ static int a6xx_gmu_rpmh_votes_init(struct a6xx_gmu *gmu)
 	struct adreno_gpu *adreno_gpu = &a6xx_gpu->base;
 	const struct a6xx_info *info = adreno_gpu->info->a6xx;
 	struct msm_gpu *gpu = &adreno_gpu->base;
+	size_t gmxc_lvl_count;
 	const char *sec_id;
 	const u16 *gmxc;
 	int ret;
 
-	gmxc = cmd_db_read_aux_data("gmxc.lvl", NULL);
+	gmxc = a6xx_gmu_rpmh_read_arc("gmxc.lvl", &gmxc_lvl_count);
 	if (gmxc == ERR_PTR(-EPROBE_DEFER))
 		return -EPROBE_DEFER;
 
-	/* If GMxC is present, prefer that as secondary rail for GX votes */
+	/* If GMxC has levels, prefer it as the secondary rail for GX votes */
 	sec_id = IS_ERR_OR_NULL(gmxc) ? "mx.lvl" : "gmxc.lvl";
 
 	/* Build the GX votes */
-- 
2.47.3