drm/i915/intel_csr.c Fix DMC FW Loading issue on ICL.

This patch resolves the DMC FW loading issue.
Earlier DMC FW package have only one DMC FW for one stepping. But as such
there is no such restriction from Package side.
For ICL icl_dmc_ver1_07.bin binary package has DMC FW for 2 steppings.
So while reading the dmc_offset from package header, for 1st stepping
offset used to come 0x0 and was working fine till now.
But for second stepping and other steppings, offset is non zero number
and is in dwords. So we need to convert into bytes to fetch correct DMC
FW from correct place.

v2 : Added check for DMC FW max size for various gen. (Imre Deak)
v3 : Corrected naming convention for various gen. (Imre Deak)
v4 : Initialized max_fw_size to 0
v5 : Corrected DMC FW MAX_SIZE for various gen. (Imre Deak)
v6 : Fixed the typo issues.
Reviewed-by: Imre Deak <imre.deak@intel.com>
Signed-off-by: Jyoti Yadav <jyoti.r.yadav@intel.com>
Signed-off-by: Imre Deak <imre.deak@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/1535695223-4648-1-git-send-email-jyoti.r.yadav@intel.com

drivers/gpu/drm/i915/intel_csr.c

@@ -55,7 +55,9 @@ MODULE_FIRMWARE(I915_CSR_BXT);
 #define BXT_CSR_VERSION_REQUIRED	CSR_VERSION(1, 7)
 
 
-#define CSR_MAX_FW_SIZE			0x2FFF
+#define BXT_CSR_MAX_FW_SIZE		0x3000
+#define GLK_CSR_MAX_FW_SIZE		0x4000
+#define ICL_CSR_MAX_FW_SIZE		0x6000
 #define CSR_DEFAULT_FW_OFFSET		0xFFFFFFFF
 
 struct intel_css_header {
@@ -279,6 +281,7 @@ static uint32_t *parse_csr_fw(struct drm_i915_private *dev_priv,
 	struct intel_csr *csr = &dev_priv->csr;
 	const struct stepping_info *si = intel_get_stepping_info(dev_priv);
 	uint32_t dmc_offset = CSR_DEFAULT_FW_OFFSET, readcount = 0, nbytes;
+	uint32_t max_fw_size = 0;
 	uint32_t i;
 	uint32_t *dmc_payload;
 	uint32_t required_version;
@@ -359,6 +362,8 @@ static uint32_t *parse_csr_fw(struct drm_i915_private *dev_priv,
 			  si->stepping);
 		return NULL;
 	}
+	/* Convert dmc_offset into number of bytes. By default it is in dwords*/
+	dmc_offset *= 4;
 	readcount += dmc_offset;
 
 	/* Extract dmc_header information. */
@@ -391,8 +396,16 @@ static uint32_t *parse_csr_fw(struct drm_i915_private *dev_priv,
 
 	/* fw_size is in dwords, so multiplied by 4 to convert into bytes. */
 	nbytes = dmc_header->fw_size * 4;
-	if (nbytes > CSR_MAX_FW_SIZE) {
-		DRM_ERROR("DMC firmware too big (%u bytes)\n", nbytes);
+	if (INTEL_GEN(dev_priv) >= 11)
+		max_fw_size = ICL_CSR_MAX_FW_SIZE;
+	else if (IS_CANNONLAKE(dev_priv) || IS_GEMINILAKE(dev_priv))
+		max_fw_size = GLK_CSR_MAX_FW_SIZE;
+	else if (IS_GEN9(dev_priv))
+		max_fw_size = BXT_CSR_MAX_FW_SIZE;
+	else
+		MISSING_CASE(INTEL_REVID(dev_priv));
+	if (nbytes > max_fw_size) {
+		DRM_ERROR("DMC FW too big (%u bytes)\n", nbytes);
 		return NULL;
 	}
 	csr->dmc_fw_size = dmc_header->fw_size;