[PATCH 1/1] drm/i915/uc: Fix issues with overriding firmware files

[John.C.Harrison at Intel.com]

From: John Harrison <John.C.Harrison at Intel.com>

The earlier update to support reduced versioning of firmware files
introduced an issue with the firmware override module parameter. If an
invalid file was specified then an infinite loop could occur trying to
find a backup firmware.

The fix is that if an explicit override has been set, then don't scan
for backup options because there is no point anyway. The user wanted X
and if X is not available, that's their problem.

This patch also fixes up the scanning loop code so that if an invalid
file is passed in, it will exit rather than loop forever. So if the
impossible situation did somehow occur in the future, it wouldn't be
such a big problem.

Fixes: 665ae9c9ca79 ("drm/i915/uc: Support for version reduced and multiple
firmware files")
Cc: Daniele Ceraolo Spurio <daniele.ceraolospurio at intel.com>
Cc: Jani Nikula <jani.nikula at linux.intel.com>
Cc: Joonas Lahtinen <joonas.lahtinen at linux.intel.com>
Cc: Rodrigo Vivi <rodrigo.vivi at intel.com>
Cc: Tvrtko Ursulin <tvrtko.ursulin at linux.intel.com>
Cc: Matthew Brost <matthew.brost at intel.com>
Cc: Umesh Nerlige Ramappa <umesh.nerlige.ramappa at intel.com>
Cc: Matthew Auld <matthew.auld at intel.com>
Cc: Alan Previn <alan.previn.teres.alexis at intel.com>
Cc: Matt Roper <matthew.d.roper at intel.com>
Cc: Lucas De Marchi <lucas.demarchi at intel.com>
Cc: Vinay Belgaumkar <vinay.belgaumkar at intel.com>
Cc: "Thomas Hellström" <thomas.hellstrom at linux.intel.com>
Cc: Venkata Sandeep Dhanalakota <venkata.s.dhanalakota at intel.com>
Signed-off-by: John Harrison <John.C.Harrison at Intel.com>
---
 drivers/gpu/drm/i915/gt/uc/intel_uc_fw.c | 18 ++++++++++++++----
 1 file changed, 14 insertions(+), 4 deletions(-)

diff --git a/drivers/gpu/drm/i915/gt/uc/intel_uc_fw.c b/drivers/gpu/drm/i915/gt/uc/intel_uc_fw.c
index af425916cdf64..5ff98239b6c9f 100644
--- a/drivers/gpu/drm/i915/gt/uc/intel_uc_fw.c
+++ b/drivers/gpu/drm/i915/gt/uc/intel_uc_fw.c
@@ -232,6 +232,7 @@ __uc_fw_auto_select(struct drm_i915_private *i915, struct intel_uc_fw *uc_fw)
 	u32 fw_count;
 	u8 rev = INTEL_REVID(i915);
 	int i;
+	bool found;
 
 	/*
 	 * The only difference between the ADL GuC FWs is the HWConfig support.
@@ -246,6 +247,7 @@ __uc_fw_auto_select(struct drm_i915_private *i915, struct intel_uc_fw *uc_fw)
 	fw_blobs = blobs_all[uc_fw->type].blobs;
 	fw_count = blobs_all[uc_fw->type].count;
 
+	found = false;
 	for (i = 0; i < fw_count && p <= fw_blobs[i].p; i++) {
 		const struct uc_fw_blob *blob = &fw_blobs[i].blob;
 
@@ -266,9 +268,15 @@ __uc_fw_auto_select(struct drm_i915_private *i915, struct intel_uc_fw *uc_fw)
 		uc_fw->file_wanted.path = blob->path;
 		uc_fw->file_wanted.major_ver = blob->major;
 		uc_fw->file_wanted.minor_ver = blob->minor;
+		found = true;
 		break;
 	}
 
+	if (!found && uc_fw->file_selected.path) {
+		/* Failed to find a match for the last attempt?! */
+		uc_fw->file_selected.path = NULL;
+	}
+
 	/* make sure the list is ordered as expected */
 	if (IS_ENABLED(CONFIG_DRM_I915_SELFTEST) && !verified) {
 		verified = true;
@@ -553,10 +561,14 @@ int intel_uc_fw_fetch(struct intel_uc_fw *uc_fw)
 
 	err = firmware_request_nowarn(&fw, uc_fw->file_selected.path, dev);
 	memcpy(&file_ideal, &uc_fw->file_wanted, sizeof(file_ideal));
-	if (!err || intel_uc_fw_is_overridden(uc_fw))
-		goto done;
+
+	/* Any error is terminal if overriding. Don't bother searching for older versions */
+	if (err && intel_uc_fw_is_overridden(uc_fw))
+		goto fail;
 
 	while (err == -ENOENT) {
+		old_ver = true;
+
 		__uc_fw_auto_select(i915, uc_fw);
 		if (!uc_fw->file_selected.path) {
 			/*
@@ -576,8 +588,6 @@ int intel_uc_fw_fetch(struct intel_uc_fw *uc_fw)
 	if (err)
 		goto fail;
 
-	old_ver = true;
-done:
 	if (uc_fw->loaded_via_gsc)
 		err = check_gsc_manifest(fw, uc_fw);
 	else
-- 
2.37.3