Merge branch 'bugfix/eth_w5500_4byte_corruption_v4.3' into 'release/v4.3'

esp_eth: Fix w5500 read register operations (v4.3)

See merge request espressif/esp-idf!13862

components/esp_eth/src/esp_eth_mac_w5500.c

@@ -93,6 +93,7 @@ static esp_err_t w5500_read(emac_w5500_t *emac, uint32_t address, void *value, u
     esp_err_t ret = ESP_OK;
 
     spi_transaction_t trans = {
+        .flags = len <= 4 ? SPI_TRANS_USE_RXDATA : 0, // use direct reads for registers to prevent overwrites by 4-byte boundary writes
         .cmd = (address >> W5500_ADDR_OFFSET),
         .addr = ((address & 0xFFFF) | (W5500_ACCESS_MODE_READ << W5500_RWB_OFFSET) | W5500_SPI_OP_MODE_VDM),
         .length = 8 * len,
@@ -107,6 +108,9 @@ static esp_err_t w5500_read(emac_w5500_t *emac, uint32_t address, void *value, u
     } else {
         ret = ESP_ERR_TIMEOUT;
     }
+    if ((trans.flags&SPI_TRANS_USE_RXDATA) && len <= 4) {
+        memcpy(value, trans.rx_data, len);  // copy register values to output
+    }
     return ret;
 }
 
@@ -498,6 +502,16 @@ static esp_err_t emac_w5500_set_peer_pause_ability(esp_eth_mac_t *mac, uint32_t
     return ESP_ERR_NOT_SUPPORTED;
 }
 
+static inline bool is_w5500_sane_for_rxtx(emac_w5500_t *emac)
+{
+    uint8_t phycfg;
+    /* phy is ok for rx and tx operations if bits RST and LNK are set (no link down, no reset) */
+    if (w5500_read(emac, W5500_REG_PHYCFGR, &phycfg, 1) == ESP_OK && (phycfg & 0x8001)) {
+        return true;
+    }
+   return false;
+}
+
 static esp_err_t emac_w5500_transmit(esp_eth_mac_t *mac, uint8_t *buf, uint32_t length)
 {
     esp_err_t ret = ESP_OK;
@@ -521,10 +535,14 @@ static esp_err_t emac_w5500_transmit(esp_eth_mac_t *mac, uint8_t *buf, uint32_t
     MAC_CHECK(w5500_send_command(emac, W5500_SCR_SEND, 100) == ESP_OK, "issue SEND command failed", err, ESP_FAIL);
 
     // pooling the TX done event
+    int retry = 0;
     uint8_t status = 0;
-    do {
+    while (!(status & W5500_SIR_SEND)) {
         MAC_CHECK(w5500_read(emac, W5500_REG_SOCK_IR(0), &status, sizeof(status)) == ESP_OK, "read SOCK0 IR failed", err, ESP_FAIL);
-    } while (!(status & W5500_SIR_SEND));
+        if ((retry++ > 3 && !is_w5500_sane_for_rxtx(emac)) || retry > 10) {
+            return ESP_FAIL;
+        }
+    }
     // clear the event bit
     status  = W5500_SIR_SEND;
     MAC_CHECK(w5500_write(emac, W5500_REG_SOCK_IR(0), &status, sizeof(status)) == ESP_OK, "write SOCK0 IR failed", err, ESP_FAIL);