@@ -2087,6 +2087,73 @@ struct edid *drm_get_edid(struct drm_connector *connector,
}
EXPORT_SYMBOL(drm_get_edid);
+static u32 edid_extract_panel_id(const struct edid *edid)
+{
+ /*
+ * In theory we could try to de-obfuscate this like edid_get_quirks()
+ * does, but it's easier to just deal with a 32-bit number since then
+ * it can be compared with "==".
+ *
+ * NOTE that we deal with endianness differently for the top half
+ * of this ID than for the bottom half. The bottom half (the product
+ * id) gets decoded as little endian by the EDID_PRODUCT_ID because
+ * that's how everyone seems to interpret it. The top half (the mfg_id)
+ * gets stored as big endian because that makes
+ * drm_edid_encode_panel_id() and drm_edid_decode_panel_id() easier
+ * to write (it's easier to extract the ASCII). It doesn't really
+ * matter, though, as long as the number here is unique.
+ */
+ return (u32)edid->mfg_id[0] << 24 |
+ (u32)edid->mfg_id[1] << 16 |
+ (u32)EDID_PRODUCT_ID(edid);
+}
+
+/**
+ * drm_edid_get_panel_id - Get a panel's ID through DDC
+ * @adapter: I2C adapter to use for DDC
+ *
+ * This function reads the first block of the EDID of a panel and (assuming
+ * that the EDID is valid) extracts the ID out of it. The ID is a 32-bit value
+ * (16 bits of manufacturer ID and 16 bits of per-manufacturer ID) that's
+ * supposed to be different for each different modem of panel.
+ *
+ * This function is intended to be used during early probing on devices where
+ * more than one panel might be present. Because of its intended use it must
+ * assume that the EDID of the panel is correct, at least as far as the ID
+ * is concerned (in other words, we don't process any overrides here).
+ *
+ * NOTE: it's expected that this function and drm_do_get_edid() will both
+ * be read the EDID, but there is no caching between them. Since we're only
+ * reading the first block, hopefully this extra overhead won't be too big.
+ *
+ * Return: A 32-bit ID that should be different for each make/model of panel.
+ * See the functions drm_edid_encode_panel_id() and
+ * drm_edid_decode_panel_id() for some details on the structure of this
+ * ID.
+ */
+
+u32 drm_edid_get_panel_id(struct i2c_adapter *adapter)
+{
+ struct edid *edid;
+ u32 panel_id;
+
+ edid = drm_do_get_edid_base_block(drm_do_probe_ddc_edid, adapter,
+ NULL, NULL);
+
+ /*
+ * There are no manufacturer IDs of 0, so if there is a problem reading
+ * the EDID then we'll just return 0.
+ */
+ if (IS_ERR_OR_NULL(edid))
+ return 0;
+
+ panel_id = edid_extract_panel_id(edid);
+ kfree(edid);
+
+ return panel_id;
+}
+EXPORT_SYMBOL(drm_edid_get_panel_id);
+
/**
* drm_get_edid_switcheroo - get EDID data for a vga_switcheroo output
* @connector: connector we're probing
@@ -508,6 +508,50 @@ static inline u8 drm_eld_get_conn_type(const uint8_t *eld)
return eld[DRM_ELD_SAD_COUNT_CONN_TYPE] & DRM_ELD_CONN_TYPE_MASK;
}
+/**
+ * drm_edid_encode_panel_id - Encode an ID for matching against drm_edid_get_panel_id()
+ * @vend: 3-character vendor string
+ * @product_id: The 16-bit product ID.
+ *
+ * This is a macro so that it can be calculated at compile time and used
+ * as an initializer.
+ *
+ * For instance:
+ * drm_edid_encode_panel_id("BOE", 0x2d08) => 0x09e52d08
+ *
+ * Return: a 32-bit ID per panel.
+ */
+#define drm_edid_encode_panel_id(vend, product_id) \
+ ((((u32)((vend)[0]) - '@') & 0x1f) << 26 | \
+ (((u32)((vend)[1]) - '@') & 0x1f) << 21 | \
+ (((u32)((vend)[2]) - '@') & 0x1f) << 16 | \
+ ((product_id) & 0xffff))
+
+/**
+ * drm_edid_decode_panel_id - Decode a panel ID from drm_edid_encode_panel_id()
+ * @panel_id: The panel ID to decode.
+ * @vend: A 4-byte buffer to store the 3-letter vendor string plus a '\0'
+ * termination
+ * @product_id: The product ID will be returned here.
+ *
+ * For instance, after:
+ * drm_edid_decode_panel_id(0x09e52d08, vend, &product_id)
+ * These will be true:
+ * vend[0] = 'B'
+ * vend[1] = 'O'
+ * vend[2] = 'E'
+ * vend[3] = '\0'
+ * product_id = 0x2d08
+ */
+static inline void drm_edid_decode_panel_id(u32 panel_id, char vend[4], u16 *product_id)
+{
+ *product_id = (u16)(panel_id & 0xffff);
+ vend[0] = '@' + ((panel_id >> 26) & 0x1f);
+ vend[1] = '@' + ((panel_id >> 21) & 0x1f);
+ vend[2] = '@' + ((panel_id >> 16) & 0x1f);
+ vend[3] = '\0';
+}
+
bool drm_probe_ddc(struct i2c_adapter *adapter);
struct edid *drm_do_get_edid(struct drm_connector *connector,
int (*get_edid_block)(void *data, u8 *buf, unsigned int block,
@@ -515,6 +559,7 @@ struct edid *drm_do_get_edid(struct drm_connector *connector,
void *data);
struct edid *drm_get_edid(struct drm_connector *connector,
struct i2c_adapter *adapter);
+u32 drm_edid_get_panel_id(struct i2c_adapter *adapter);
struct edid *drm_get_edid_switcheroo(struct drm_connector *connector,
struct i2c_adapter *adapter);
struct edid *drm_edid_duplicate(const struct edid *edid);