openwrt/target/linux/pistachio/patches-4.9/106-spi-img-spfi-finish-every-transfer-cleanly.patch

From 5fcca3fd4b621d7b5bdeca18d36dfc6ca6cfe383 Mon Sep 17 00:00:00 2001
From: Ionela Voinescu <ionela.voinescu@imgtec.com>
Date: Wed, 10 Aug 2016 11:42:26 +0100
Subject: spi: img-spfi: finish every transfer cleanly

Before this change, the interrupt status bit that signaled
the end of a tranfers was cleared in the wait_all_done
function. That functionality triggered issues for DMA
duplex transactions where the wait function was called
twice, in both the TX and RX callbacks.

In order to fix the issue, clear all interrupt data bits
at the end of a PIO transfer or at the end of both TX and RX
duplex transfers, if the transfer is not a pending tranfer
(command waiting for data). After that, the status register
is checked for new incoming data or new data requests to be
signaled. If SPFI finished cleanly, no new interrupt data
bits should be set.

Signed-off-by: Ionela Voinescu <ionela.voinescu@imgtec.com>
---
 drivers/spi/spi-img-spfi.c | 49 +++++++++++++++++++++++++++++++++-------------
 1 file changed, 35 insertions(+), 14 deletions(-)

--- a/drivers/spi/spi-img-spfi.c
+++ b/drivers/spi/spi-img-spfi.c
@@ -83,6 +83,14 @@
 #define SPFI_INTERRUPT_SDE			BIT(1)
 #define SPFI_INTERRUPT_SDTRIG			BIT(0)
 
+#define SPFI_INTERRUPT_DATA_BITS		(SPFI_INTERRUPT_SDHF |\
+						SPFI_INTERRUPT_SDFUL |\
+						SPFI_INTERRUPT_GDEX32BIT |\
+						SPFI_INTERRUPT_GDHF |\
+						SPFI_INTERRUPT_GDFUL |\
+						SPFI_INTERRUPT_ALLDONETRIG |\
+						SPFI_INTERRUPT_GDEX8BIT)
+
 /*
  * There are four parallel FIFOs of 16 bytes each.  The word buffer
  * (*_32BIT_VALID_DATA) accesses all four FIFOs at once, resulting in an
@@ -144,6 +152,23 @@ static inline void spfi_reset(struct img
 	spfi_writel(spfi, 0, SPFI_CONTROL);
 }
 
+static inline void spfi_finish(struct img_spfi *spfi)
+{
+	if (!(spfi->complete))
+		return;
+
+	/* Clear data bits as all transfers(TX and RX) have finished */
+	spfi_writel(spfi, SPFI_INTERRUPT_DATA_BITS, SPFI_INTERRUPT_CLEAR);
+	if (spfi_readl(spfi, SPFI_INTERRUPT_STATUS) & SPFI_INTERRUPT_DATA_BITS) {
+		dev_err(spfi->dev, "SPFI did not finish transfer cleanly.\n");
+		spfi_reset(spfi);
+	}
+	/* Disable SPFI for it not to interfere with pending transactions */
+	spfi_writel(spfi,
+		    spfi_readl(spfi, SPFI_CONTROL) & ~SPFI_CONTROL_SPFI_EN,
+		    SPFI_CONTROL);
+}
+
 static int spfi_wait_all_done(struct img_spfi *spfi)
 {
 	unsigned long timeout = jiffies + msecs_to_jiffies(50);
@@ -152,19 +177,9 @@ static int spfi_wait_all_done(struct img
 		return 0;
 
 	while (time_before(jiffies, timeout)) {
-		u32 status = spfi_readl(spfi, SPFI_INTERRUPT_STATUS);
-
-		if (status & SPFI_INTERRUPT_ALLDONETRIG) {
-			spfi_writel(spfi, SPFI_INTERRUPT_ALLDONETRIG,
-				    SPFI_INTERRUPT_CLEAR);
-			/*
-			 * Disable SPFI for it not to interfere with
-			 * pending transactions
-			 */
-			spfi_writel(spfi, spfi_readl(spfi, SPFI_CONTROL)
-			& ~SPFI_CONTROL_SPFI_EN, SPFI_CONTROL);
+		if (spfi_readl(spfi, SPFI_INTERRUPT_STATUS) &
+		    SPFI_INTERRUPT_ALLDONETRIG)
 			return 0;
-		}
 		cpu_relax();
 	}
 
@@ -296,6 +311,8 @@ static int img_spfi_start_pio(struct spi
 	}
 
 	ret = spfi_wait_all_done(spfi);
+	spfi_finish(spfi);
+
 	if (ret < 0)
 		return ret;
 
@@ -311,8 +328,10 @@ static void img_spfi_dma_rx_cb(void *dat
 
 	spin_lock_irqsave(&spfi->lock, flags);
 	spfi->rx_dma_busy = false;
-	if (!spfi->tx_dma_busy)
+	if (!spfi->tx_dma_busy) {
+		spfi_finish(spfi);
 		spi_finalize_current_transfer(spfi->master);
+	}
 	spin_unlock_irqrestore(&spfi->lock, flags);
 }
 
@@ -325,8 +344,10 @@ static void img_spfi_dma_tx_cb(void *dat
 
 	spin_lock_irqsave(&spfi->lock, flags);
 	spfi->tx_dma_busy = false;
-	if (!spfi->rx_dma_busy)
+	if (!spfi->rx_dma_busy) {
+		spfi_finish(spfi);
 		spi_finalize_current_transfer(spfi->master);
+	}
 	spin_unlock_irqrestore(&spfi->lock, flags);
 }