drm/nouveau/device: fix changing endianess code to work on older GPUs (dcd292c1) · Commits · 戴 / test

drivers/gpu/drm/nouveau/nvkm/engine/device/base.c

+26 −13

Original line number	Diff line number	Diff line
		@@ -2924,17 +2924,34 @@ nvkm_device_del(struct nvkm_device **pdevice)
		}
		}

		/* returns true if the GPU is in the CPU native byte order */
		static inline bool
		nvkm_device_endianness(struct nvkm_device *device)
		{
		u32 boot1 = nvkm_rd32(device, 0x000004) & 0x01000001;
		#ifdef __BIG_ENDIAN
		if (!boot1)
		return false;
		const bool big_endian = true;
		#else
		if (boot1)
		return false;
		const bool big_endian = false;
		#endif

		/* Read NV_PMC_BOOT_1, and assume non-functional endian switch if it
		* doesn't contain the expected values.
		*/
		u32 pmc_boot_1 = nvkm_rd32(device, 0x000004);
		if (pmc_boot_1 && pmc_boot_1 != 0x01000001)
		return !big_endian; /* Assume GPU is LE in this case. */

		/* 0 means LE and 0x01000001 means BE GPU. Condition is true when
		* GPU/CPU endianness don't match.
		*/
		if (big_endian == !pmc_boot_1) {
		nvkm_wr32(device, 0x000004, 0x01000001);
		nvkm_rd32(device, 0x000000);
		if (nvkm_rd32(device, 0x000004) != (big_endian ? 0x01000001 : 0x00000000))
		return !big_endian; /* Assume GPU is LE on any unexpected read-back. */
		}

		/* CPU/GPU endianness should (hopefully) match. */
		return true;
		}

		@@ -2986,16 +3003,12 @@ nvkm_device_ctor(const struct nvkm_device_func *func,
		/* identify the chipset, and determine classes of subdev/engines */
		if (detect) {
		/* switch mmio to cpu's native endianness */
		if (!nvkm_device_endianness(device)) {
		nvkm_wr32(device, 0x000004, 0x01000001);
		nvkm_rd32(device, 0x000000);
		if (!nvkm_device_endianness(device)) {
		nvdev_error(device,
		"GPU not supported on big-endian\n");
		"Couldn't switch GPU to CPUs endianess\n");
		ret = -ENOSYS;
		goto done;
		}
		}

		boot0 = nvkm_rd32(device, 0x000000);

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