[PATCH 01/11] drm/xe: Detect each GMD_ID IP in a loop

[Stuart Summers <stuart.summers@intel.com>]

handle_gmdid() open coded the graphics and media detection twice, with
the two copies subtly disagreeing: a missing media IP was tolerated,
while graphics reporting version 0 was reported as an unknown version.

Describe the per IP differences in a small table and walk it, so both
IPs are detected the same way and an absent IP of either kind simply
leaves its descriptor NULL. Deciding whether the resulting combination
is usable is left to the caller, which is unchanged in still demanding
a graphics IP.

Signed-off-by: Stuart Summers <stuart.summers@intel.com>
---
 drivers/gpu/drm/xe/xe_pci.c | 70 ++++++++++++++++++++++---------------
 1 file changed, 42 insertions(+), 28 deletions(-)

diff --git a/drivers/gpu/drm/xe/xe_pci.c b/drivers/gpu/drm/xe/xe_pci.c
index ba23ec60477b..a59bb1c9b478 100644
--- a/drivers/gpu/drm/xe/xe_pci.c
+++ b/drivers/gpu/drm/xe/xe_pci.c
@@ -704,9 +704,21 @@ static const struct xe_ip *find_media_ip(unsigned int verx100)
 	return NULL;
 }
 
+static const struct xe_gmdid_desc {
+	const char *name;
+	const struct xe_ip *(*find_ip)(unsigned int verx100);
+} gmdid_descs[] = {
+	[GMDID_GRAPHICS] = { "graphics", find_graphics_ip },
+	[GMDID_MEDIA] = { "media", find_media_ip },
+};
+
 /*
  * Read IP version from hardware and select graphics/media IP descriptors
  * based on the result.
+ *
+ * Each IP is detected independently and any of them may legitimately be fused
+ * off or otherwise absent, in which case its descriptor is left NULL.  Deciding
+ * whether the resulting combination is usable is up to the caller.
  */
 static int handle_gmdid(struct xe_device *xe,
 			const struct xe_ip **graphics_ip,
@@ -714,36 +726,38 @@ static int handle_gmdid(struct xe_device *xe,
 			u32 *graphics_revid,
 			u32 *media_revid)
 {
-	u32 ver;
-	int ret;
-
-	*graphics_ip = NULL;
-	*media_ip = NULL;
-
-	ret = read_gmdid(xe, GMDID_GRAPHICS, &ver, graphics_revid);
-	if (ret)
-		return ret;
-
-	*graphics_ip = find_graphics_ip(ver);
-	if (!*graphics_ip) {
-		xe_log_err(xe, REGS, -EINVAL,
-			   "Hardware reports unknown graphics version %u.%02u\n",
-			   ver / 100, ver % 100);
-	}
-
-	ret = read_gmdid(xe, GMDID_MEDIA, &ver, media_revid);
-	if (ret)
-		return ret;
+	const struct xe_ip **ips[] = {
+		[GMDID_GRAPHICS] = graphics_ip,
+		[GMDID_MEDIA] = media_ip,
+	};
+	u32 *revids[] = {
+		[GMDID_GRAPHICS] = graphics_revid,
+		[GMDID_MEDIA] = media_revid,
+	};
+
+	for (enum xe_gmdid_type type = 0; type < ARRAY_SIZE(gmdid_descs); type++) {
+		const struct xe_gmdid_desc *desc = &gmdid_descs[type];
+		u32 ver;
+		int ret;
+
+		*ips[type] = NULL;
+		*revids[type] = 0;
+
+		ret = read_gmdid(xe, type, &ver, revids[type]);
+		if (ret)
+			return ret;
 
-	/* Media may legitimately be fused off / not present */
-	if (ver == 0)
-		return 0;
+		/* The IP may legitimately be fused off / not present */
+		if (!ver) {
+			*revids[type] = 0;
+			continue;
+		}
 
-	*media_ip = find_media_ip(ver);
-	if (!*media_ip) {
-		xe_log_err(xe, REGS, -EINVAL,
-			   "Hardware reports unknown media version %u.%02u\n",
-			   ver / 100, ver % 100);
+		*ips[type] = desc->find_ip(ver);
+		if (!*ips[type])
+			xe_log_err(xe, REGS, -EINVAL,
+				   "Hardware reports unknown %s version %u.%02u\n",
+				   desc->name, ver / 100, ver % 100);
 	}
 
 	return 0;
-- 
2.43.0