spi: s3c64xx: extend description of compatible's fifo_depth

The FIFO depth specified with the compatibles's data is used where all
the instances of the IP define the same FIFO depth. It naturally has
higher precedence than the FIFO depth specified via DT. Specifying FIFO
depth in DT becomes superfluous in this case. Extend comment about
compatible's FIFO depth.

Signed-off-by: Tudor Ambarus <tudor.ambarus@linaro.org>
Reviewed-by: Krzysztof Kozlowski <krzysztof.kozlowski@linaro.org>
Reviewed-by: Sam Protsenko <semen.protsenko@linaro.org>
Link: https://patch.msgid.link/20250214-spi-s3c64xx-fifo-depth-v1-1-e1b1915e3ee7@linaro.org
Signed-off-by: Mark Brown <broonie@kernel.org>

Author: ambarus

drivers/spi/spi-s3c64xx.c

@@ -139,7 +139,9 @@ struct s3c64xx_spi_dma_data {
  * struct s3c64xx_spi_port_config - SPI Controller hardware info
  * @fifo_lvl_mask: [DEPRECATED] use @{rx, tx}_fifomask instead.
  * @rx_lvl_offset: [DEPRECATED] use @{rx,tx}_fifomask instead.
- * @fifo_depth: depth of the FIFO.
+ * @fifo_depth: depth of the FIFOs. Used by compatibles where all the instances
+ *              of the IP define the same FIFO depth. It has higher precedence
+ *              than the FIFO depth specified via DT.
  * @rx_fifomask: SPI_STATUS.RX_FIFO_LVL mask. Shifted mask defining the field's
  *               length and position.
  * @tx_fifomask: SPI_STATUS.TX_FIFO_LVL mask. Shifted mask defining the field's