drm/i915/dmc: Step away from symbolic links

Load specific firmware versions for the DMC instead of using symbolic
links. The currently recommended versions are: SKL 1.26, KBL 1.01 and
BXT 1.07.

Certain DMC versions need workarounds in the driver which forces us to
have a tight dependency between firmware and driver. In order to be able
to provide a tested and known working configuration we must lock down on
a specific DMC firmware version.

Cc: Rodrigo Vivi <rodrigo.vivi@intel.com>
Cc: Imre Deak <imre.deak@intel.com>
Cc: Mika Kuoppala <mika.kuoppala@linux.intel.com>
Signed-off-by: Patrik Jakobsson <patrik.jakobsson@linux.intel.com>
Acked-by: Jani Nikula <jani.nikula@intel.com>
Reviewed-by: Mika Kuoppala <mika.kuoppala@intel.com>
Acked-by: Rodrigo Vivi <rodrigo.vivi@intel.com>
Signed-off-by: Rodrigo Vivi <rodrigo.vivi@intel.com>
Link: http://patchwork.freedesktop.org/patch/msgid/1463391057-32350-1-git-send-email-patrik.jakobsson@linux.intel.com

drivers/gpu/drm/i915/intel_csr.c

@@ -41,15 +41,15 @@
  * be moved to FW_FAILED.
  */
 
-#define I915_CSR_KBL "i915/kbl_dmc_ver1.bin"
+#define I915_CSR_KBL "i915/kbl_dmc_ver1_01.bin"
 MODULE_FIRMWARE(I915_CSR_KBL);
 #define KBL_CSR_VERSION_REQUIRED	CSR_VERSION(1, 1)
 
-#define I915_CSR_SKL "i915/skl_dmc_ver1.bin"
+#define I915_CSR_SKL "i915/skl_dmc_ver1_26.bin"
 MODULE_FIRMWARE(I915_CSR_SKL);
-#define SKL_CSR_VERSION_REQUIRED	CSR_VERSION(1, 23)
+#define SKL_CSR_VERSION_REQUIRED	CSR_VERSION(1, 26)
 
-#define I915_CSR_BXT "i915/bxt_dmc_ver1.bin"
+#define I915_CSR_BXT "i915/bxt_dmc_ver1_07.bin"
 MODULE_FIRMWARE(I915_CSR_BXT);
 #define BXT_CSR_VERSION_REQUIRED	CSR_VERSION(1, 7)
 
@@ -286,7 +286,7 @@ static uint32_t *parse_csr_fw(struct drm_i915_private *dev_priv,
 	uint32_t dmc_offset = CSR_DEFAULT_FW_OFFSET, readcount = 0, nbytes;
 	uint32_t i;
 	uint32_t *dmc_payload;
-	uint32_t required_min_version;
+	uint32_t required_version;
 
 	if (!fw)
 		return NULL;
@@ -303,24 +303,23 @@ static uint32_t *parse_csr_fw(struct drm_i915_private *dev_priv,
 	csr->version = css_header->version;
 
 	if (IS_KABYLAKE(dev_priv)) {
-		required_min_version = KBL_CSR_VERSION_REQUIRED;
+		required_version = KBL_CSR_VERSION_REQUIRED;
 	} else if (IS_SKYLAKE(dev_priv)) {
-		required_min_version = SKL_CSR_VERSION_REQUIRED;
+		required_version = SKL_CSR_VERSION_REQUIRED;
 	} else if (IS_BROXTON(dev_priv)) {
-		required_min_version = BXT_CSR_VERSION_REQUIRED;
+		required_version = BXT_CSR_VERSION_REQUIRED;
 	} else {
 		MISSING_CASE(INTEL_REVID(dev_priv));
-		required_min_version = 0;
+		required_version = 0;
 	}
 
-	if (csr->version < required_min_version) {
-		DRM_INFO("Refusing to load old DMC firmware v%u.%u,"
-			 " please upgrade to v%u.%u or later"
-			   " [" FIRMWARE_URL "].\n",
+	if (csr->version != required_version) {
+		DRM_INFO("Refusing to load DMC firmware v%u.%u,"
+			 " please use v%u.%u [" FIRMWARE_URL "].\n",
 			 CSR_VERSION_MAJOR(csr->version),
 			 CSR_VERSION_MINOR(csr->version),
-			 CSR_VERSION_MAJOR(required_min_version),
-			 CSR_VERSION_MINOR(required_min_version));
+			 CSR_VERSION_MAJOR(required_version),
+			 CSR_VERSION_MINOR(required_version));
 		return NULL;
 	}