[ Nathan, it turns out that Smatch has been broken with regards to
uninitialized variables for a while so I'm going through my backlog
of warnings. No idea if you already reported this one.
- dan]
Hello Akhil P Oommen,
The patch a6f24383f6c0: "drm/msm/a6xx: Fix llcc configuration for
a660 gpu" from Jul 30, 2021, leads to the following Smatch static
checker warning:
drivers/gpu/drm/msm/adreno/a6xx_gpu.c:1480 a6xx_llc_activate()
error: uninitialized symbol 'gpu_scid'.
drivers/gpu/drm/msm/adreno/a6xx_gpu.c
1423 static void a6xx_llc_activate(struct a6xx_gpu *a6xx_gpu)
1424 {
1425 struct adreno_gpu *adreno_gpu = &a6xx_gpu->base;
1426 struct msm_gpu *gpu = &adreno_gpu->base;
1427 u32 gpu_scid, cntl1_regval = 0;
^^^^^^^^^^^^
1428
1429 if (IS_ERR(a6xx_gpu->llc_mmio))
1430 return;
1431
1432 if (!llcc_slice_activate(a6xx_gpu->llc_slice)) {
1433 gpu_scid = llcc_get_slice_id(a6xx_gpu->llc_slice);
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
1434
1435 gpu_scid &= 0x1f;
1436 cntl1_regval = (gpu_scid << 0) | (gpu_scid << 5) | (gpu_scid << 10) |
1437 (gpu_scid << 15) | (gpu_scid << 20);
1438 }
1439
1440 /*
1441 * For targets with a MMU500, activate the slice but don't program the
1442 * register. The XBL will take care of that.
1443 */
1444 if (!llcc_slice_activate(a6xx_gpu->htw_llc_slice)) {
1445 if (!a6xx_gpu->have_mmu500) {
1446 u32 gpuhtw_scid = llcc_get_slice_id(a6xx_gpu->htw_llc_slice);
1447
1448 gpuhtw_scid &= 0x1f;
1449 cntl1_regval |= FIELD_PREP(GENMASK(29, 25), gpuhtw_scid);
1450 }
1451 }
1452
1453 if (!cntl1_regval)
1454 return;
1455
1456 /*
1457 * Program the slice IDs for the various GPU blocks and GPU MMU
1458 * pagetables
1459 */
1460 if (!a6xx_gpu->have_mmu500) {
1461 a6xx_llc_write(a6xx_gpu,
1462 REG_A6XX_CX_MISC_SYSTEM_CACHE_CNTL_1, cntl1_regval);
1463
1464 /*
1465 * Program cacheability overrides to not allocate cache
1466 * lines on a write miss
1467 */
1468 a6xx_llc_rmw(a6xx_gpu,
1469 REG_A6XX_CX_MISC_SYSTEM_CACHE_CNTL_0, 0xF, 0x03);
1470 return;
1471 }
1472
1473 gpu_rmw(gpu, REG_A6XX_GBIF_SCACHE_CNTL1, GENMASK(24, 0), cntl1_regval);
1474
1475 /* On A660, the SCID programming for UCHE traffic is done in
1476 * A6XX_GBIF_SCACHE_CNTL0[14:10]
1477 */
1478 if (adreno_is_a660_family(adreno_gpu))
1479 gpu_rmw(gpu, REG_A6XX_GBIF_SCACHE_CNTL0, (0x1f << 10) |
--> 1480 (1 << 8), (gpu_scid << 10) | (1 << 8));
^^^^^^^^^^^^^^
Uninitialized if llcc_slice_activate() failed.
1481 }
regards,
dan carpenter
