xf86drm: Add a vendor function to decode the format modifier

As format modifiers can be encoded in quite complex forms, the static
table previously added is not sufficient to retrieve, extract and decode
the token formats to a human-readable string.  This patch introduces a
vendor specific callback which could be used to perform an additional
search to match up with vendor encoding scheme, which, will be used
first, before resorting to searching the static table.

With it, add support for decoding the ARM format modifiers.

Signed-off-by: Marius Vlad <marius.vlad@collabora.com>

xf86drm.c

@@ -152,6 +152,104 @@ struct drmFormatModifierVendorInfo {
 
 #include "generated_static_table_fourcc.h"
 
+struct drmVendorInfo {
+    uint8_t vendor;
+    char *(*vendor_cb)(uint64_t modifier);
+};
+
+struct drmFormatVendorModifierInfo {
+    uint64_t modifier;
+    const char *modifier_name;
+};
+
+static char *
+drmGetFormatModifierNameFromArm(uint64_t modifier);
+
+static const struct drmVendorInfo modifier_format_vendor_table[] = {
+    { DRM_FORMAT_MOD_VENDOR_ARM, drmGetFormatModifierNameFromArm },
+};
+
+#ifndef AFBC_FORMAT_MOD_MODE_VALUE_MASK
+#define AFBC_FORMAT_MOD_MODE_VALUE_MASK	0x000fffffffffffffULL
+#endif
+
+static const struct drmFormatVendorModifierInfo arm_mode_value_table[] = {
+    { AFBC_FORMAT_MOD_YTR,          "YTR" },
+    { AFBC_FORMAT_MOD_SPLIT,        "SPLIT" },
+    { AFBC_FORMAT_MOD_SPARSE,       "SPARSE" },
+    { AFBC_FORMAT_MOD_CBR,          "CBR" },
+    { AFBC_FORMAT_MOD_TILED,        "TILED" },
+    { AFBC_FORMAT_MOD_SC,           "SC" },
+    { AFBC_FORMAT_MOD_DB,           "DB" },
+    { AFBC_FORMAT_MOD_BCH,          "BCH" },
+    { AFBC_FORMAT_MOD_USM,          "USM" },
+};
+
+static char *
+drmGetFormatModifierNameFromArm(uint64_t modifier)
+{
+    uint64_t type = (modifier >> 52) & 0xf;
+    uint64_t mode_value = modifier & AFBC_FORMAT_MOD_MODE_VALUE_MASK;
+    uint64_t block_size = mode_value & AFBC_FORMAT_MOD_BLOCK_SIZE_MASK;
+
+    FILE *fp;
+    char *modifier_name = NULL;
+    size_t size = 0;
+    unsigned int i;
+
+    const char *block = NULL;
+    const char *mode = NULL;
+    bool did_print_mode = false;
+
+    /* misc type is already handled by the static table */
+    if (type != DRM_FORMAT_MOD_ARM_TYPE_AFBC)
+        return NULL;
+
+    fp = open_memstream(&modifier_name, &size);
+    if (!fp)
+        return NULL;
+
+    /* add block, can only have a (single) block */
+    switch (block_size) {
+    case AFBC_FORMAT_MOD_BLOCK_SIZE_16x16:
+        block = "16x16";
+        break;
+    case AFBC_FORMAT_MOD_BLOCK_SIZE_32x8:
+        block = "32x8";
+        break;
+    case AFBC_FORMAT_MOD_BLOCK_SIZE_64x4:
+        block = "64x4";
+        break;
+    case AFBC_FORMAT_MOD_BLOCK_SIZE_32x8_64x4:
+        block = "32x8_64x4";
+        break;
+    }
+
+    if (!block) {
+        fclose(fp);
+        free(modifier_name);
+        return NULL;
+    }
+
+    fprintf(fp, "BLOCK_SIZE=%s,", block);
+
+    /* add mode */
+    for (i = 0; i < ARRAY_SIZE(arm_mode_value_table); i++) {
+        if (arm_mode_value_table[i].modifier & mode_value) {
+            mode = arm_mode_value_table[i].modifier_name;
+            if (!did_print_mode) {
+                fprintf(fp, "MODE=%s", mode);
+                did_print_mode = true;
+            } else {
+                fprintf(fp, "|%s", mode);
+            }
+        }
+    }
+
+    fclose(fp);
+    return modifier_name;
+}
+
 static unsigned log2_int(unsigned x)
 {
     unsigned l;
@@ -4651,8 +4749,8 @@ drmGetFormatModifierVendor(uint64_t modifier)
 /** Retrieves a human-readable representation string from a format token
  * modifier
  *
- * If the format modifier was not in the table, this function would return
+ * If the dedicated function was not able to extract a valid name or searching
- * NULL.
+ * the format modifier was not in the table, this function would return NULL.
  *
  * \param modifier the token format
  * \return a malloc'ed string representation of the modifier. Caller is
@@ -4662,6 +4760,17 @@ drmGetFormatModifierVendor(uint64_t modifier)
 drm_public char *
 drmGetFormatModifierName(uint64_t modifier)
 {
-    char *modifier_found = drmGetFormatModifierFromSimpleTokens(modifier);
+    uint8_t vendorid = fourcc_mod_get_vendor(modifier);
+    char *modifier_found = NULL;
+    unsigned int i;
+
+    for (i = 0; i < ARRAY_SIZE(modifier_format_vendor_table); i++) {
+        if (modifier_format_vendor_table[i].vendor == vendorid)
+            modifier_found = modifier_format_vendor_table[i].vendor_cb(modifier);
+    }
+
+    if (!modifier_found)
+        return drmGetFormatModifierFromSimpleTokens(modifier);
+
     return modifier_found;
 }