spi: xilinx: increase number of retries before declaring stall

SPI devices using a (relative) slow frequency need a larger time.

For instance, microblaze running at 83.25MHz and performing a
3 bytes transaction using a 10MHz/16 = 625kHz needed this stall
value increased to at least 20. The SPI device is quite slow, but
also is the microblaze, so set this value to 32 to give it even
more margin.

Signed-off-by: Alvaro Gamez Machado <[email protected]>
Reviewed-by: Ricardo Ribalda <[email protected]>
Link: https://patch.msgid.link/[email protected]
Signed-off-by: Mark Brown <[email protected]>

Author: agamez

drivers/spi/spi-xilinx.c

@@ -300,7 +300,7 @@ static int xilinx_spi_txrx_bufs(struct spi_device *spi, struct spi_transfer *t)
 
 		/* Read out all the data from the Rx FIFO */
 		rx_words = n_words;
-		stalled = 10;
+		stalled = 32;
 		while (rx_words) {
 			if (rx_words == n_words && !(stalled--) &&
 			    !(sr & XSPI_SR_TX_EMPTY_MASK) &&