can: mcp251xfd: mcp251xfd_register_get_dev_id(): use correct length to read dev_id

The device ID register is 32 bits wide. The driver uses incorrectly the size of a pointer to a u32 to calculate the length of the SPI transfer. This results in a read of 2 registers on 64 bit platforms. This is no problem on the Linux side, as the RX buffer of the SPI transfer is large enough. In the mpc251xfd chip this results in the read of an undocumented register. So far no problems were observed. Fix the length of the SPI transfer to read the device ID register only.

Marc Kleine-Budde committed 4 years ago

Commit 0ff32bf1 parent d5a972f1 file · +1 −1Browse files

Unified · Split

drivers/net/can/spi/mcp251xfd/mcp251xfd-core.c+1−1

@@ -1778,7 +1778,7 @@ mcp251xfd_register_get_dev_id(const struct mcp251xfd_priv priv, u32 dev_id, · 1777 unmodified lines
1778	xfer[0].len = sizeof(buf_tx->cmd);	1778	xfer[0].len = sizeof(buf_tx->cmd);
1779	xfer[0].speed_hz = priv->spi_max_speed_hz_slow;	1779	xfer[0].speed_hz = priv->spi_max_speed_hz_slow;
1780	xfer[1].rx_buf = buf_rx->data;	1780	xfer[1].rx_buf = buf_rx->data;
1781	xfer[1].len = sizeof(dev_id);	1781	xfer[1].len = sizeof(*dev_id);
1782	xfer[1].speed_hz = priv->spi_max_speed_hz_fast;	1782	xfer[1].speed_hz = priv->spi_max_speed_hz_fast;
1783		1783
1784	mcp251xfd_spi_cmd_read_nocrc(&buf_tx->cmd, MCP251XFD_REG_DEVID);	1784	mcp251xfd_spi_cmd_read_nocrc(&buf_tx->cmd, MCP251XFD_REG_DEVID);