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esp_eth: Fix w5500 to correctly read registers on -Os

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Reading SPI data may come in 4-byte units and thus result in unwanted
overwrites if smaller size registers read, especially if multiple placed
one after another. Fixed by using direct reads to `trans` structure for
sizes smaller or equal to 4.

Closes https://github.com/espressif/esp-idf/issues/6579
This commit is contained in:
David Cermak
2021-04-07 21:15:24 +02:00
committed by bot
parent 97f007c08c
commit 8534799d66
1 changed files with 4 additions and 0 deletions
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4
components/esp_eth/src/esp_eth_mac_w5500.c
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@@ -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;
}