[PATCH] spi: spi-imx: Revert "spi: spi-imx: add PIO polling support"

[Fabio Estevam <festevam@xxxxxxxxx>]

This reverts commit 07e7593877882fbd07c55b26b7dcf88760449323.

Since commit 07e759387788 ("spi: spi-imx: add PIO polling support") it is
no longer possible to do successful SPI NOR programming on
imx8mm-kontron-n801x-som, even though the copy operation returns no errors
to the user.

After programming the SPI NOR flash from Linux, the board fails to
boot from SPI NOR, leading to an unbootable system.

Revert it to fix the regression.

Cc: stable@xxxxxxxxxx
Fixes: 07e759387788 ("spi: spi-imx: add PIO polling support")
Signed-off-by: Fabio Estevam <festevam@xxxxxxxxx>
---
 drivers/spi/spi-imx.c | 66 -------------------------------------------
 1 file changed, 66 deletions(-)

diff --git a/drivers/spi/spi-imx.c b/drivers/spi/spi-imx.c
index a4bda03d3a8e..b946d98a8d66 100644
--- a/drivers/spi/spi-imx.c
+++ b/drivers/spi/spi-imx.c
@@ -31,12 +31,6 @@ static bool use_dma = true;
 module_param(use_dma, bool, 0644);
 MODULE_PARM_DESC(use_dma, "Enable usage of DMA when available (default)");
 
-/* define polling limits */
-static unsigned int polling_limit_us = 30;
-module_param(polling_limit_us, uint, 0664);
-MODULE_PARM_DESC(polling_limit_us,
-		 "time in us to run a transfer in polling mode\n");
-
 #define MXC_RPM_TIMEOUT		2000 /* 2000ms */
 
 #define MXC_CSPIRXDATA		0x00
@@ -1490,54 +1484,6 @@ static int spi_imx_pio_transfer(struct spi_device *spi,
 	return 0;
 }
 
-static int spi_imx_poll_transfer(struct spi_device *spi,
-				 struct spi_transfer *transfer)
-{
-	struct spi_imx_data *spi_imx = spi_controller_get_devdata(spi->controller);
-	unsigned long timeout;
-
-	spi_imx->tx_buf = transfer->tx_buf;
-	spi_imx->rx_buf = transfer->rx_buf;
-	spi_imx->count = transfer->len;
-	spi_imx->txfifo = 0;
-	spi_imx->remainder = 0;
-
-	/* fill in the fifo before timeout calculations if we are
-	 * interrupted here, then the data is getting transferred by
-	 * the HW while we are interrupted
-	 */
-	spi_imx_push(spi_imx);
-
-	timeout = spi_imx_calculate_timeout(spi_imx, transfer->len) + jiffies;
-	while (spi_imx->txfifo) {
-		/* RX */
-		while (spi_imx->txfifo &&
-		       spi_imx->devtype_data->rx_available(spi_imx)) {
-			spi_imx->rx(spi_imx);
-			spi_imx->txfifo--;
-		}
-
-		/* TX */
-		if (spi_imx->count) {
-			spi_imx_push(spi_imx);
-			continue;
-		}
-
-		if (spi_imx->txfifo &&
-		    time_after(jiffies, timeout)) {
-
-			dev_err_ratelimited(&spi->dev,
-					    "timeout period reached: jiffies: %lu- falling back to interrupt mode\n",
-					    jiffies - timeout);
-
-			/* fall back to interrupt mode */
-			return spi_imx_pio_transfer(spi, transfer);
-		}
-	}
-
-	return 0;
-}
-
 static int spi_imx_pio_transfer_slave(struct spi_device *spi,
 				      struct spi_transfer *transfer)
 {
@@ -1587,7 +1533,6 @@ static int spi_imx_transfer_one(struct spi_controller *controller,
 				struct spi_transfer *transfer)
 {
 	struct spi_imx_data *spi_imx = spi_controller_get_devdata(spi->controller);
-	unsigned long hz_per_byte, byte_limit;
 
 	spi_imx_setupxfer(spi, transfer);
 	transfer->effective_speed_hz = spi_imx->spi_bus_clk;
@@ -1599,17 +1544,6 @@ static int spi_imx_transfer_one(struct spi_controller *controller,
 	if (spi_imx->slave_mode)
 		return spi_imx_pio_transfer_slave(spi, transfer);
 
-	/*
-	 * Calculate the estimated time in us the transfer runs. Find
-	 * the number of Hz per byte per polling limit.
-	 */
-	hz_per_byte = polling_limit_us ? ((8 + 4) * USEC_PER_SEC) / polling_limit_us : 0;
-	byte_limit = hz_per_byte ? transfer->effective_speed_hz / hz_per_byte : 1;
-
-	/* run in polling mode for short transfers */
-	if (transfer->len < byte_limit)
-		return spi_imx_poll_transfer(spi, transfer);
-
 	if (spi_imx->usedma)
 		return spi_imx_dma_transfer(spi_imx, transfer);
 
-- 
2.25.1