linux-kernel - Applied "spi: qup: allow multiple DMA transactions per spi xfer" to the spi tree

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Date:   Tue, 08 Aug 2017 12:18:01 +0100
From:   Mark Brown <broonie@...nel.org>
To:     Varadarajan Narayanan <varada@...eaurora.org>
Cc:     Matthew McClintock <mmcclint@...eaurora.org>,
        Mark Brown <broonie@...nel.org>, broonie@...nel.org,
        robh+dt@...nel.org, mark.rutland@....com, andy.gross@...aro.org,
        david.brown@...aro.org, linux-spi@...r.kernel.org,
        devicetree@...r.kernel.org, linux-kernel@...r.kernel.org,
        linux-arm-msm@...r.kernel.org, linux-soc@...r.kernel.org,
        Matthew McClintock <mmcclint@...eaurora.org>,
        linux-spi@...r.kernel.org
Subject: Applied "spi: qup: allow multiple DMA transactions per spi xfer" to the spi tree

The patch

   spi: qup: allow multiple DMA transactions per spi xfer

has been applied to the spi tree at

   git://git.kernel.org/pub/scm/linux/kernel/git/broonie/spi.git 

All being well this means that it will be integrated into the linux-next
tree (usually sometime in the next 24 hours) and sent to Linus during
the next merge window (or sooner if it is a bug fix), however if
problems are discovered then the patch may be dropped or reverted.  

You may get further e-mails resulting from automated or manual testing
and review of the tree, please engage with people reporting problems and
send followup patches addressing any issues that are reported if needed.

If any updates are required or you are submitting further changes they
should be sent as incremental updates against current git, existing
patches will not be replaced.

Please add any relevant lists and maintainers to the CCs when replying
to this mail.

Thanks,
Mark

>From 5884e17ef3cb3dac2e83e466246cf033bfba0e2f Mon Sep 17 00:00:00 2001
From: Varadarajan Narayanan <varada@...eaurora.org>
Date: Fri, 28 Jul 2017 12:22:59 +0530
Subject: [PATCH] spi: qup: allow multiple DMA transactions per spi xfer

Much like the block mode changes, we are breaking up DMA transactions
into 64K chunks so we can reset the QUP engine.

Signed-off-by: Matthew McClintock <mmcclint@...eaurora.org>
Signed-off-by: Varadarajan Narayanan <varada@...eaurora.org>
Signed-off-by: Mark Brown <broonie@...nel.org>
---
 drivers/spi/spi-qup.c | 92 ++++++++++++++++++++++++++++++++++++---------------
 1 file changed, 66 insertions(+), 26 deletions(-)

diff --git a/drivers/spi/spi-qup.c b/drivers/spi/spi-qup.c
index 1af3b41ac12d..3c2c2c0ed9ab 100644
--- a/drivers/spi/spi-qup.c
+++ b/drivers/spi/spi-qup.c
@@ -418,12 +418,35 @@ static void spi_qup_dma_terminate(struct spi_master *master,
 		dmaengine_terminate_all(master->dma_rx);
 }
 
+static u32 spi_qup_sgl_get_nents_len(struct scatterlist *sgl, u32 max,
+				     u32 *nents)
+{
+	struct scatterlist *sg;
+	u32 total = 0;
+
+	*nents = 0;
+
+	for (sg = sgl; sg; sg = sg_next(sg)) {
+		unsigned int len = sg_dma_len(sg);
+
+		/* check for overflow as well as limit */
+		if (((total + len) < total) || ((total + len) > max))
+			break;
+
+		total += len;
+		(*nents)++;
+	}
+
+	return total;
+}
+
 static int spi_qup_do_dma(struct spi_device *spi, struct spi_transfer *xfer,
 			  unsigned long timeout)
 {
 	dma_async_tx_callback rx_done = NULL, tx_done = NULL;
 	struct spi_master *master = spi->master;
 	struct spi_qup *qup = spi_master_get_devdata(master);
+	struct scatterlist *tx_sgl, *rx_sgl;
 	int ret;
 
 	if (xfer->rx_buf)
@@ -431,40 +454,57 @@ static int spi_qup_do_dma(struct spi_device *spi, struct spi_transfer *xfer,
 	else if (xfer->tx_buf)
 		tx_done = spi_qup_dma_done;
 
-	ret = spi_qup_io_config(spi, xfer);
-	if (ret)
-		return ret;
+	rx_sgl = xfer->rx_sg.sgl;
+	tx_sgl = xfer->tx_sg.sgl;
 
-	/* before issuing the descriptors, set the QUP to run */
-	ret = spi_qup_set_state(qup, QUP_STATE_RUN);
-	if (ret) {
-		dev_warn(qup->dev, "%s(%d): cannot set RUN state\n",
-				__func__, __LINE__);
-		return ret;
-	}
+	do {
+		u32 rx_nents, tx_nents;
+
+		if (rx_sgl)
+			qup->n_words = spi_qup_sgl_get_nents_len(rx_sgl,
+					SPI_MAX_XFER, &rx_nents) / qup->w_size;
+		if (tx_sgl)
+			qup->n_words = spi_qup_sgl_get_nents_len(tx_sgl,
+					SPI_MAX_XFER, &tx_nents) / qup->w_size;
+		if (!qup->n_words)
+			return -EIO;
 
-	if (xfer->rx_buf) {
-		ret = spi_qup_prep_sg(master, xfer->rx_sg.sgl,
-				      xfer->rx_sg.nents, DMA_DEV_TO_MEM,
-				      rx_done);
+		ret = spi_qup_io_config(spi, xfer);
 		if (ret)
 			return ret;
 
-		dma_async_issue_pending(master->dma_rx);
-	}
-
-	if (xfer->tx_buf) {
-		ret = spi_qup_prep_sg(master, xfer->tx_sg.sgl,
-				      xfer->tx_sg.nents, DMA_MEM_TO_DEV,
-				      tx_done);
-		if (ret)
+		/* before issuing the descriptors, set the QUP to run */
+		ret = spi_qup_set_state(qup, QUP_STATE_RUN);
+		if (ret) {
+			dev_warn(qup->dev, "cannot set RUN state\n");
 			return ret;
+		}
+		if (rx_sgl) {
+			ret = spi_qup_prep_sg(master, rx_sgl, rx_nents,
+					      DMA_DEV_TO_MEM, rx_done);
+			if (ret)
+				return ret;
+			dma_async_issue_pending(master->dma_rx);
+		}
 
-		dma_async_issue_pending(master->dma_tx);
-	}
+		if (tx_sgl) {
+			ret = spi_qup_prep_sg(master, tx_sgl, tx_nents,
+					      DMA_MEM_TO_DEV, tx_done);
+			if (ret)
+				return ret;
+
+			dma_async_issue_pending(master->dma_tx);
+		}
+
+		if (!wait_for_completion_timeout(&qup->done, timeout))
+			return -ETIMEDOUT;
+
+		for (; rx_sgl && rx_nents--; rx_sgl = sg_next(rx_sgl))
+			;
+		for (; tx_sgl && tx_nents--; tx_sgl = sg_next(tx_sgl))
+			;
 
-	if (!wait_for_completion_timeout(&qup->done, timeout))
-		return -ETIMEDOUT;
+	} while (rx_sgl || tx_sgl);
 
 	return 0;
 }
-- 
2.13.2