[PATCH v1 0/8] Append several fixes and improvements in STM32 DMA

[PATCH v1 0/8] Append several fixes and improvements in STM32 DMA

[Pierre-Yves MORDRET]

This patchset appends several fixes and some improvements for STM32 DMAv2.
This includes:
        * Introduce DMA features bitfield
        * Threshold manages with bitfield feature
        * Improve memory burst management
        * Improve DMA IRQ status handling
        * Fix max items per transfer to match FIFO Size
        * Properly mask irq bits to avoid overlaping
        * Fix incomplete configuration in cyclic mode
        * Fix typo and reported checkpatch warnings

---
  Version history:
    v1:
        * Initial
---

Pierre-Yves MORDRET (8):
  dt-bindings: stm32-dma: introduce DMA features bitfield
  dmaengine: stm32-dma: threshold manages with bitfield feature
  dmaengine: stm32-dma: Improve memory burst management
  dmaengine: stm32-dma: fix DMA IRQ status handling
  dmaengine: stm32-dma: fix max items per transfer
  dmaengine: stm32-dma: properly mask irq bits
  dmaengine: stm32-dma: fix incomplete configuration in cyclic mode
  dmaengine: stm32-dma: fix typo and reported checkpatch warnings

 .../devicetree/bindings/dma/stm32-dma.txt          |   6 +-
 drivers/dma/stm32-dma.c                            | 287 +++++++++++++++++----
 2 files changed, 243 insertions(+), 50 deletions(-)

-- 
2.7.4

[PATCH v1 1/8] dt-bindings: stm32-dma: introduce DMA features bitfield

[Pierre-Yves MORDRET]

This bitfield intends to address features to be activated within the
driver. Initially the mask was only meant for FIFO Threshold management.
Backward compatibility is preserved but the meaning of this field has been
extended to features instead of only threshold.

Signed-off-by: Pierre-Yves MORDRET <pierre-yves.mordret@st.com>
---
  Version history:
    v1:
       * Initial
---
---
 Documentation/devicetree/bindings/dma/stm32-dma.txt | 6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)

diff --git a/Documentation/devicetree/bindings/dma/stm32-dma.txt b/Documentation/devicetree/bindings/dma/stm32-dma.txt
index 0b55718..c5f5190 100644
--- a/Documentation/devicetree/bindings/dma/stm32-dma.txt
+++ b/Documentation/devicetree/bindings/dma/stm32-dma.txt
@@ -62,14 +62,14 @@ channel: a phandle to the DMA controller plus the following four integer cells:
 	0x1: medium
 	0x2: high
 	0x3: very high
-4. A 32bit mask specifying the DMA FIFO threshold configuration which are device
-   dependent:
- -bit 0-1: Fifo threshold
+4. A 32bit bitfield value specifying DMA features which are device dependent:
+ -bit 0-1: DMA FIFO threshold selection
 	0x0: 1/4 full FIFO
 	0x1: 1/2 full FIFO
 	0x2: 3/4 full FIFO
 	0x3: full FIFO
 
+
 Example:
 
 	usart1: serial@40011000 {
-- 
2.7.4

[PATCH v1 2/8] dmaengine: stm32-dma: threshold manages with bitfield feature

[Pierre-Yves MORDRET]

>From now on, DMA bitfield is to manage DMA FIFO Threshold.

Signed-off-by: Pierre-Yves MORDRET <pierre-yves.mordret@st.com>
---
  Version history:
    v1:
       * Initial
---
---
 drivers/dma/stm32-dma.c | 19 ++++++++++++++++---
 1 file changed, 16 insertions(+), 3 deletions(-)

diff --git a/drivers/dma/stm32-dma.c b/drivers/dma/stm32-dma.c
index 786fc8f..4099948 100644
--- a/drivers/dma/stm32-dma.c
+++ b/drivers/dma/stm32-dma.c
@@ -116,6 +116,10 @@
 #define STM32_DMA_MAX_DATA_PARAM	0x03
 #define STM32_DMA_MAX_BURST		16
 
+/* DMA Features */
+#define STM32_DMA_THRESHOLD_FTR_MASK	GENMASK(1, 0)
+#define STM32_DMA_THRESHOLD_FTR_GET(n)	((n) & STM32_DMA_THRESHOLD_FTR_MASK)
+
 enum stm32_dma_width {
 	STM32_DMA_BYTE,
 	STM32_DMA_HALF_WORD,
@@ -129,11 +133,18 @@ enum stm32_dma_burst_size {
 	STM32_DMA_BURST_INCR16,
 };
 
+/**
+ * struct stm32_dma_cfg - STM32 DMA custom configuration
+ * @channel_id: channel ID
+ * @request_line: DMA request
+ * @stream_config: 32bit mask specifying the DMA channel configuration
+ * @features: 32bit mask specifying the DMA Feature list
+ */
 struct stm32_dma_cfg {
 	u32 channel_id;
 	u32 request_line;
 	u32 stream_config;
-	u32 threshold;
+	u32 features;
 };
 
 struct stm32_dma_chan_reg {
@@ -171,6 +182,7 @@ struct stm32_dma_chan {
 	u32 next_sg;
 	struct dma_slave_config	dma_sconfig;
 	struct stm32_dma_chan_reg chan_reg;
+	u32 threshold;
 };
 
 struct stm32_dma_device {
@@ -976,7 +988,8 @@ static void stm32_dma_set_config(struct stm32_dma_chan *chan,
 	/* Enable Interrupts  */
 	chan->chan_reg.dma_scr |= STM32_DMA_SCR_TEIE | STM32_DMA_SCR_TCIE;
 
-	chan->chan_reg.dma_sfcr = cfg->threshold & STM32_DMA_SFCR_FTH_MASK;
+	chan->threshold = STM32_DMA_THRESHOLD_FTR_GET(cfg->features);
+	chan->chan_reg.dma_sfcr = STM32_DMA_SFCR_FTH(chan->threshold);
 }
 
 static struct dma_chan *stm32_dma_of_xlate(struct of_phandle_args *dma_spec,
@@ -996,7 +1009,7 @@ static struct dma_chan *stm32_dma_of_xlate(struct of_phandle_args *dma_spec,
 	cfg.channel_id = dma_spec->args[0];
 	cfg.request_line = dma_spec->args[1];
 	cfg.stream_config = dma_spec->args[2];
-	cfg.threshold = dma_spec->args[3];
+	cfg.features = dma_spec->args[3];
 
 	if ((cfg.channel_id >= STM32_DMA_MAX_CHANNELS) ||
 	    (cfg.request_line >= STM32_DMA_MAX_REQUEST_ID)) {
-- 
2.7.4

[PATCH v1 3/8] dmaengine: stm32-dma: Improve memory burst management

[Pierre-Yves MORDRET]

This patch improves memory burst capability using best burst size
according to transferred buffer size from/to memory.

>From now on, memory burst is not necessarily same as with peripheral
burst one and fifo threshold is directly managed by this driver in order
to fit with computed memory burst.

Signed-off-by: M'boumba Cedric Madianga <cedric.madianga@gmail.com>
Signed-off-by: Pierre-Yves MORDRET <pierre-yves.mordret@st.com>
---
  Version history:
    v1:
       * Initial
---
---
 drivers/dma/stm32-dma.c | 204 +++++++++++++++++++++++++++++++++++++++++-------
 1 file changed, 175 insertions(+), 29 deletions(-)

diff --git a/drivers/dma/stm32-dma.c b/drivers/dma/stm32-dma.c
index 4099948..a7edd6d 100644
--- a/drivers/dma/stm32-dma.c
+++ b/drivers/dma/stm32-dma.c
@@ -5,6 +5,7 @@
  *
  * Copyright (C) M'boumba Cedric Madianga 2015
  * Author: M'boumba Cedric Madianga <cedric.madianga@gmail.com>
+ *         Pierre-Yves Mordret <pierre-yves.mordret@st.com>
  *
  * License terms:  GNU General Public License (GPL), version 2
  */
@@ -114,6 +115,8 @@
 #define STM32_DMA_MAX_CHANNELS		0x08
 #define STM32_DMA_MAX_REQUEST_ID	0x08
 #define STM32_DMA_MAX_DATA_PARAM	0x03
+#define STM32_DMA_FIFO_SIZE		16	/* FIFO is 16 bytes */
+#define STM32_DMA_MIN_BURST		4
 #define STM32_DMA_MAX_BURST		16
 
 /* DMA Features */
@@ -183,6 +186,8 @@ struct stm32_dma_chan {
 	struct dma_slave_config	dma_sconfig;
 	struct stm32_dma_chan_reg chan_reg;
 	u32 threshold;
+	u32 mem_burst;
+	u32 mem_width;
 };
 
 struct stm32_dma_device {
@@ -247,6 +252,85 @@ static int stm32_dma_get_width(struct stm32_dma_chan *chan,
 	}
 }
 
+static enum dma_slave_buswidth stm32_dma_get_max_width(u32 buf_len,
+						       u32 threshold)
+{
+	enum dma_slave_buswidth max_width;
+
+	if (threshold == STM32_DMA_FIFO_THRESHOLD_FULL)
+		max_width = DMA_SLAVE_BUSWIDTH_4_BYTES;
+	else
+		max_width = DMA_SLAVE_BUSWIDTH_2_BYTES;
+
+	while ((buf_len < max_width  || buf_len % max_width) &&
+	       max_width > DMA_SLAVE_BUSWIDTH_1_BYTE)
+		max_width = max_width >> 1;
+
+	return max_width;
+}
+
+static bool stm32_dma_fifo_threshold_is_allowed(u32 burst, u32 threshold,
+						enum dma_slave_buswidth width)
+{
+	u32 remaining;
+
+	if (width != DMA_SLAVE_BUSWIDTH_UNDEFINED) {
+		if (burst != 0) {
+			/*
+			 * If number of beats fit in several whole bursts
+			 * this configuration is allowed.
+			 */
+			remaining = ((STM32_DMA_FIFO_SIZE / width) *
+				     (threshold + 1) / 4) % burst;
+
+			if (remaining == 0)
+				return true;
+		} else {
+			return true;
+		}
+	}
+
+	return false;
+}
+
+static bool stm32_dma_is_burst_possible(u32 buf_len, u32 threshold)
+{
+	switch (threshold) {
+	case STM32_DMA_FIFO_THRESHOLD_FULL:
+		if (buf_len >= STM32_DMA_MAX_BURST)
+			return true;
+		else
+			return false;
+	case STM32_DMA_FIFO_THRESHOLD_HALFFULL:
+		if (buf_len >= STM32_DMA_MAX_BURST / 2)
+			return true;
+		else
+			return false;
+	default:
+		return false;
+	}
+}
+
+static u32 stm32_dma_get_best_burst(u32 buf_len, u32 max_burst, u32 threshold,
+				    enum dma_slave_buswidth width)
+{
+	u32 best_burst = max_burst;
+
+	if (best_burst == 1 || !stm32_dma_is_burst_possible(buf_len, threshold))
+		return 0;
+
+	while ((buf_len < best_burst * width && best_burst > 1) ||
+	       !stm32_dma_fifo_threshold_is_allowed(best_burst, threshold,
+						    width)) {
+		if (best_burst > STM32_DMA_MIN_BURST)
+			best_burst = best_burst >> 1;
+		else
+			best_burst = 0;
+	}
+
+	return best_burst;
+}
+
 static int stm32_dma_get_burst(struct stm32_dma_chan *chan, u32 maxburst)
 {
 	switch (maxburst) {
@@ -266,12 +350,12 @@ static int stm32_dma_get_burst(struct stm32_dma_chan *chan, u32 maxburst)
 }
 
 static void stm32_dma_set_fifo_config(struct stm32_dma_chan *chan,
-				      u32 src_maxburst, u32 dst_maxburst)
+				      u32 src_burst, u32 dst_burst)
 {
 	chan->chan_reg.dma_sfcr &= ~STM32_DMA_SFCR_MASK;
 	chan->chan_reg.dma_scr &= ~STM32_DMA_SCR_DMEIE;
 
-	if ((!src_maxburst) && (!dst_maxburst)) {
+	if (!src_burst && !dst_burst) {
 		/* Using direct mode */
 		chan->chan_reg.dma_scr |= STM32_DMA_SCR_DMEIE;
 	} else {
@@ -584,37 +668,52 @@ static void stm32_dma_issue_pending(struct dma_chan *c)
 
 static int stm32_dma_set_xfer_param(struct stm32_dma_chan *chan,
 				    enum dma_transfer_direction direction,
-				    enum dma_slave_buswidth *buswidth)
+				    enum dma_slave_buswidth *buswidth,
+				    u32 buf_len)
 {
 	enum dma_slave_buswidth src_addr_width, dst_addr_width;
 	int src_bus_width, dst_bus_width;
 	int src_burst_size, dst_burst_size;
-	u32 src_maxburst, dst_maxburst;
-	u32 dma_scr = 0;
+	u32 src_maxburst, dst_maxburst, src_best_burst, dst_best_burst;
+	u32 dma_scr, threshold;
 
 	src_addr_width = chan->dma_sconfig.src_addr_width;
 	dst_addr_width = chan->dma_sconfig.dst_addr_width;
 	src_maxburst = chan->dma_sconfig.src_maxburst;
 	dst_maxburst = chan->dma_sconfig.dst_maxburst;
+	threshold = chan->threshold;
 
 	switch (direction) {
 	case DMA_MEM_TO_DEV:
+		/* Set device data size */
 		dst_bus_width = stm32_dma_get_width(chan, dst_addr_width);
 		if (dst_bus_width < 0)
 			return dst_bus_width;
 
-		dst_burst_size = stm32_dma_get_burst(chan, dst_maxburst);
+		/* Set device burst size */
+		dst_best_burst = stm32_dma_get_best_burst(buf_len,
+							  dst_maxburst,
+							  threshold,
+							  dst_addr_width);
+
+		dst_burst_size = stm32_dma_get_burst(chan, dst_best_burst);
 		if (dst_burst_size < 0)
 			return dst_burst_size;
 
-		if (!src_addr_width)
-			src_addr_width = dst_addr_width;
-
+		/* Set memory data size */
+		src_addr_width = stm32_dma_get_max_width(buf_len, threshold);
+		chan->mem_width = src_addr_width;
 		src_bus_width = stm32_dma_get_width(chan, src_addr_width);
 		if (src_bus_width < 0)
 			return src_bus_width;
 
-		src_burst_size = stm32_dma_get_burst(chan, src_maxburst);
+		/* Set memory burst size */
+		src_maxburst = STM32_DMA_MAX_BURST;
+		src_best_burst = stm32_dma_get_best_burst(buf_len,
+							  src_maxburst,
+							  threshold,
+							  src_addr_width);
+		src_burst_size = stm32_dma_get_burst(chan, src_best_burst);
 		if (src_burst_size < 0)
 			return src_burst_size;
 
@@ -624,27 +723,46 @@ static int stm32_dma_set_xfer_param(struct stm32_dma_chan *chan,
 			STM32_DMA_SCR_PBURST(dst_burst_size) |
 			STM32_DMA_SCR_MBURST(src_burst_size);
 
+		/* Set FIFO threshold */
+		chan->chan_reg.dma_sfcr &= ~STM32_DMA_SFCR_FTH_MASK;
+		chan->chan_reg.dma_sfcr |= STM32_DMA_SFCR_FTH(threshold);
+
+		/* Set peripheral address */
 		chan->chan_reg.dma_spar = chan->dma_sconfig.dst_addr;
 		*buswidth = dst_addr_width;
 		break;
 
 	case DMA_DEV_TO_MEM:
+		/* Set device data size */
 		src_bus_width = stm32_dma_get_width(chan, src_addr_width);
 		if (src_bus_width < 0)
 			return src_bus_width;
 
-		src_burst_size = stm32_dma_get_burst(chan, src_maxburst);
+		/* Set device burst size */
+		src_best_burst = stm32_dma_get_best_burst(buf_len,
+							  src_maxburst,
+							  threshold,
+							  src_addr_width);
+		chan->mem_burst = src_best_burst;
+		src_burst_size = stm32_dma_get_burst(chan, src_best_burst);
 		if (src_burst_size < 0)
 			return src_burst_size;
 
-		if (!dst_addr_width)
-			dst_addr_width = src_addr_width;
-
+		/* Set memory data size */
+		dst_addr_width = stm32_dma_get_max_width(buf_len, threshold);
+		chan->mem_width = dst_addr_width;
 		dst_bus_width = stm32_dma_get_width(chan, dst_addr_width);
 		if (dst_bus_width < 0)
 			return dst_bus_width;
 
-		dst_burst_size = stm32_dma_get_burst(chan, dst_maxburst);
+		/* Set memory burst size */
+		dst_maxburst = STM32_DMA_MAX_BURST;
+		dst_best_burst = stm32_dma_get_best_burst(buf_len,
+							  dst_maxburst,
+							  threshold,
+							  dst_addr_width);
+		chan->mem_burst = dst_best_burst;
+		dst_burst_size = stm32_dma_get_burst(chan, dst_best_burst);
 		if (dst_burst_size < 0)
 			return dst_burst_size;
 
@@ -654,6 +772,11 @@ static int stm32_dma_set_xfer_param(struct stm32_dma_chan *chan,
 			STM32_DMA_SCR_PBURST(src_burst_size) |
 			STM32_DMA_SCR_MBURST(dst_burst_size);
 
+		/* Set FIFO threshold */
+		chan->chan_reg.dma_sfcr &= ~STM32_DMA_SFCR_FTH_MASK;
+		chan->chan_reg.dma_sfcr |= STM32_DMA_SFCR_FTH(threshold);
+
+		/* Set peripheral address */
 		chan->chan_reg.dma_spar = chan->dma_sconfig.src_addr;
 		*buswidth = chan->dma_sconfig.src_addr_width;
 		break;
@@ -663,8 +786,9 @@ static int stm32_dma_set_xfer_param(struct stm32_dma_chan *chan,
 		return -EINVAL;
 	}
 
-	stm32_dma_set_fifo_config(chan, src_maxburst, dst_maxburst);
+	stm32_dma_set_fifo_config(chan, src_best_burst, dst_best_burst);
 
+	/* Set DMA control register */
 	chan->chan_reg.dma_scr &= ~(STM32_DMA_SCR_DIR_MASK |
 			STM32_DMA_SCR_PSIZE_MASK | STM32_DMA_SCR_MSIZE_MASK |
 			STM32_DMA_SCR_PBURST_MASK | STM32_DMA_SCR_MBURST_MASK);
@@ -704,10 +828,6 @@ static struct dma_async_tx_descriptor *stm32_dma_prep_slave_sg(
 	if (!desc)
 		return NULL;
 
-	ret = stm32_dma_set_xfer_param(chan, direction, &buswidth);
-	if (ret < 0)
-		goto err;
-
 	/* Set peripheral flow controller */
 	if (chan->dma_sconfig.device_fc)
 		chan->chan_reg.dma_scr |= STM32_DMA_SCR_PFCTRL;
@@ -715,6 +835,11 @@ static struct dma_async_tx_descriptor *stm32_dma_prep_slave_sg(
 		chan->chan_reg.dma_scr &= ~STM32_DMA_SCR_PFCTRL;
 
 	for_each_sg(sgl, sg, sg_len, i) {
+		ret = stm32_dma_set_xfer_param(chan, direction, &buswidth,
+					       sg_dma_len(sg));
+		if (ret < 0)
+			goto err;
+
 		desc->sg_req[i].len = sg_dma_len(sg);
 
 		nb_data_items = desc->sg_req[i].len / buswidth;
@@ -779,7 +904,7 @@ static struct dma_async_tx_descriptor *stm32_dma_prep_dma_cyclic(
 		return NULL;
 	}
 
-	ret = stm32_dma_set_xfer_param(chan, direction, &buswidth);
+	ret = stm32_dma_set_xfer_param(chan, direction, &buswidth, period_len);
 	if (ret < 0)
 		return NULL;
 
@@ -828,9 +953,10 @@ static struct dma_async_tx_descriptor *stm32_dma_prep_dma_memcpy(
 	dma_addr_t src, size_t len, unsigned long flags)
 {
 	struct stm32_dma_chan *chan = to_stm32_dma_chan(c);
-	u32 num_sgs;
+	enum dma_slave_buswidth max_width;
 	struct stm32_dma_desc *desc;
 	size_t xfer_count, offset;
+	u32 num_sgs, best_burst, dma_burst, threshold;
 	int i;
 
 	num_sgs = DIV_ROUND_UP(len, STM32_DMA_MAX_DATA_ITEMS);
@@ -838,25 +964,34 @@ static struct dma_async_tx_descriptor *stm32_dma_prep_dma_memcpy(
 	if (!desc)
 		return NULL;
 
+	threshold = chan->threshold;
+
 	for (offset = 0, i = 0; offset < len; offset += xfer_count, i++) {
 		xfer_count = min_t(size_t, len - offset,
 				   STM32_DMA_MAX_DATA_ITEMS);
 
-		desc->sg_req[i].len = xfer_count;
+		/* Compute best burst size */
+		max_width = DMA_SLAVE_BUSWIDTH_1_BYTE;
+		best_burst = stm32_dma_get_best_burst(len, STM32_DMA_MAX_BURST,
+						      threshold, max_width);
+		dma_burst = stm32_dma_get_burst(chan, best_burst);
 
 		stm32_dma_clear_reg(&desc->sg_req[i].chan_reg);
 		desc->sg_req[i].chan_reg.dma_scr =
 			STM32_DMA_SCR_DIR(STM32_DMA_MEM_TO_MEM) |
+			STM32_DMA_SCR_PBURST(dma_burst) |
+			STM32_DMA_SCR_MBURST(dma_burst) |
 			STM32_DMA_SCR_MINC |
 			STM32_DMA_SCR_PINC |
 			STM32_DMA_SCR_TCIE |
 			STM32_DMA_SCR_TEIE;
-		desc->sg_req[i].chan_reg.dma_sfcr = STM32_DMA_SFCR_DMDIS |
-			STM32_DMA_SFCR_FTH(STM32_DMA_FIFO_THRESHOLD_FULL) |
-			STM32_DMA_SFCR_FEIE;
+		desc->sg_req[i].chan_reg.dma_sfcr |= STM32_DMA_SFCR_MASK;
+		desc->sg_req[i].chan_reg.dma_sfcr |=
+			STM32_DMA_SFCR_FTH(threshold);
 		desc->sg_req[i].chan_reg.dma_spar = src + offset;
 		desc->sg_req[i].chan_reg.dma_sm0ar = dest + offset;
 		desc->sg_req[i].chan_reg.dma_sndtr = xfer_count;
+		desc->sg_req[i].len = xfer_count;
 	}
 
 	desc->num_sgs = num_sgs;
@@ -881,6 +1016,7 @@ static size_t stm32_dma_desc_residue(struct stm32_dma_chan *chan,
 				     struct stm32_dma_desc *desc,
 				     u32 next_sg)
 {
+	u32 modulo, burst_size;
 	u32 residue = 0;
 	int i;
 
@@ -888,8 +1024,10 @@ static size_t stm32_dma_desc_residue(struct stm32_dma_chan *chan,
 	 * In cyclic mode, for the last period, residue = remaining bytes from
 	 * NDTR
 	 */
-	if (chan->desc->cyclic && next_sg == 0)
-		return stm32_dma_get_remaining_bytes(chan);
+	if (chan->desc->cyclic && next_sg == 0) {
+		residue = stm32_dma_get_remaining_bytes(chan);
+		goto end;
+	}
 
 	/*
 	 * For all other periods in cyclic mode, and in sg mode,
@@ -900,6 +1038,15 @@ static size_t stm32_dma_desc_residue(struct stm32_dma_chan *chan,
 		residue += desc->sg_req[i].len;
 	residue += stm32_dma_get_remaining_bytes(chan);
 
+end:
+	if (!chan->mem_burst)
+		return residue;
+
+	burst_size = chan->mem_burst * chan->mem_width;
+	modulo = residue % burst_size;
+	if (modulo)
+		residue = residue - modulo + burst_size;
+
 	return residue;
 }
 
@@ -989,7 +1136,6 @@ static void stm32_dma_set_config(struct stm32_dma_chan *chan,
 	chan->chan_reg.dma_scr |= STM32_DMA_SCR_TEIE | STM32_DMA_SCR_TCIE;
 
 	chan->threshold = STM32_DMA_THRESHOLD_FTR_GET(cfg->features);
-	chan->chan_reg.dma_sfcr = STM32_DMA_SFCR_FTH(chan->threshold);
 }
 
 static struct dma_chan *stm32_dma_of_xlate(struct of_phandle_args *dma_spec,
-- 
2.7.4

[PATCH v1 4/8] dmaengine: stm32-dma: fix DMA IRQ status handling

[Pierre-Yves MORDRET]

Update the way Transfer Complete and Half Transfer Complete status are
acknowledge. Even if HTI is not enabled its status is shown when reading
registers, driver has to clear it gently and not raise an error.

Signed-off-by: Pierre-Yves MORDRET <pierre-yves.mordret@st.com>
---
  Version history:
    v1:
       * Initial
---
---
 drivers/dma/stm32-dma.c | 29 +++++++++++++++++++++++++----
 1 file changed, 25 insertions(+), 4 deletions(-)

diff --git a/drivers/dma/stm32-dma.c b/drivers/dma/stm32-dma.c
index a7edd6d..0685961 100644
--- a/drivers/dma/stm32-dma.c
+++ b/drivers/dma/stm32-dma.c
@@ -34,9 +34,14 @@
 #define STM32_DMA_LIFCR			0x0008 /* DMA Low Int Flag Clear Reg */
 #define STM32_DMA_HIFCR			0x000c /* DMA High Int Flag Clear Reg */
 #define STM32_DMA_TCI			BIT(5) /* Transfer Complete Interrupt */
+#define STM32_DMA_HTI			BIT(4) /* Half Transfer Interrupt */
 #define STM32_DMA_TEI			BIT(3) /* Transfer Error Interrupt */
 #define STM32_DMA_DMEI			BIT(2) /* Direct Mode Error Interrupt */
 #define STM32_DMA_FEI			BIT(0) /* FIFO Error Interrupt */
+#define STM32_DMA_MASKI			(STM32_DMA_TCI \
+					 | STM32_DMA_TEI \
+					 | STM32_DMA_DMEI \
+					 | STM32_DMA_FEI)
 
 /* DMA Stream x Configuration Register */
 #define STM32_DMA_SCR(x)		(0x0010 + 0x18 * (x)) /* x = 0..7 */
@@ -637,13 +642,29 @@ static irqreturn_t stm32_dma_chan_irq(int irq, void *devid)
 	status = stm32_dma_irq_status(chan);
 	scr = stm32_dma_read(dmadev, STM32_DMA_SCR(chan->id));
 
-	if ((status & STM32_DMA_TCI) && (scr & STM32_DMA_SCR_TCIE)) {
+	if (status & STM32_DMA_TCI) {
 		stm32_dma_irq_clear(chan, STM32_DMA_TCI);
-		stm32_dma_handle_chan_done(chan);
-
-	} else {
+		if (scr & STM32_DMA_SCR_TCIE)
+			stm32_dma_handle_chan_done(chan);
+		status &= ~STM32_DMA_TCI;
+	}
+	if (status & STM32_DMA_HTI) {
+		stm32_dma_irq_clear(chan, STM32_DMA_HTI);
+		status &= ~STM32_DMA_HTI;
+	}
+	if (status & STM32_DMA_FEI) {
+		stm32_dma_irq_clear(chan, STM32_DMA_FEI);
+		status &= ~STM32_DMA_FEI;
+		if (!(scr & STM32_DMA_SCR_EN))
+			dev_err(chan2dev(chan), "FIFO Error\n");
+		else
+			dev_dbg(chan2dev(chan), "FIFO over/underrun\n");
+	}
+	if (status) {
 		stm32_dma_irq_clear(chan, status);
 		dev_err(chan2dev(chan), "DMA error: status=0x%08x\n", status);
+		if (!(scr & STM32_DMA_SCR_EN))
+			dev_err(chan2dev(chan), "chan disabled by HW\n");
 	}
 
 	spin_unlock(&chan->vchan.lock);
-- 
2.7.4

[PATCH v1 5/8] dmaengine: stm32-dma: fix max items per transfer

[Pierre-Yves MORDRET]

Having 0 in item counter register is valid and stands for a "No or Ended
transfer". Therefore valid transfer starts from @+0 to @+0xFFFE leading to
unaligned scatter gather at boundary. Thus it's safer to round down this
value on its FIFO size (16 Bytes).

Signed-off-by: Pierre-Yves MORDRET <pierre-yves.mordret@st.com>
---
  Version history:
    v1:
       * Initial
---
---
 drivers/dma/stm32-dma.c | 19 +++++++++++--------
 1 file changed, 11 insertions(+), 8 deletions(-)

diff --git a/drivers/dma/stm32-dma.c b/drivers/dma/stm32-dma.c
index 0685961..f9d3c84 100644
--- a/drivers/dma/stm32-dma.c
+++ b/drivers/dma/stm32-dma.c
@@ -38,10 +38,6 @@
 #define STM32_DMA_TEI			BIT(3) /* Transfer Error Interrupt */
 #define STM32_DMA_DMEI			BIT(2) /* Direct Mode Error Interrupt */
 #define STM32_DMA_FEI			BIT(0) /* FIFO Error Interrupt */
-#define STM32_DMA_MASKI			(STM32_DMA_TCI \
-					 | STM32_DMA_TEI \
-					 | STM32_DMA_DMEI \
-					 | STM32_DMA_FEI)
 
 /* DMA Stream x Configuration Register */
 #define STM32_DMA_SCR(x)		(0x0010 + 0x18 * (x)) /* x = 0..7 */
@@ -117,6 +113,13 @@
 #define STM32_DMA_FIFO_THRESHOLD_FULL			0x03
 
 #define STM32_DMA_MAX_DATA_ITEMS	0xffff
+/*
+ * Valid transfer starts from @0 to @0xFFFE leading to unaligned scatter
+ * gather at boundary. Thus it's safer to round down this value on FIFO
+ * size (16 Bytes)
+ */
+#define STM32_DMA_ALIGNED_MAX_DATA_ITEMS	\
+	ALIGN_DOWN(STM32_DMA_MAX_DATA_ITEMS, 16)
 #define STM32_DMA_MAX_CHANNELS		0x08
 #define STM32_DMA_MAX_REQUEST_ID	0x08
 #define STM32_DMA_MAX_DATA_PARAM	0x03
@@ -864,7 +867,7 @@ static struct dma_async_tx_descriptor *stm32_dma_prep_slave_sg(
 		desc->sg_req[i].len = sg_dma_len(sg);
 
 		nb_data_items = desc->sg_req[i].len / buswidth;
-		if (nb_data_items > STM32_DMA_MAX_DATA_ITEMS) {
+		if (nb_data_items > STM32_DMA_ALIGNED_MAX_DATA_ITEMS) {
 			dev_err(chan2dev(chan), "nb items not supported\n");
 			goto err;
 		}
@@ -930,7 +933,7 @@ static struct dma_async_tx_descriptor *stm32_dma_prep_dma_cyclic(
 		return NULL;
 
 	nb_data_items = period_len / buswidth;
-	if (nb_data_items > STM32_DMA_MAX_DATA_ITEMS) {
+	if (nb_data_items > STM32_DMA_ALIGNED_MAX_DATA_ITEMS) {
 		dev_err(chan2dev(chan), "number of items not supported\n");
 		return NULL;
 	}
@@ -980,7 +983,7 @@ static struct dma_async_tx_descriptor *stm32_dma_prep_dma_memcpy(
 	u32 num_sgs, best_burst, dma_burst, threshold;
 	int i;
 
-	num_sgs = DIV_ROUND_UP(len, STM32_DMA_MAX_DATA_ITEMS);
+	num_sgs = DIV_ROUND_UP(len, STM32_DMA_ALIGNED_MAX_DATA_ITEMS);
 	desc = stm32_dma_alloc_desc(num_sgs);
 	if (!desc)
 		return NULL;
@@ -989,7 +992,7 @@ static struct dma_async_tx_descriptor *stm32_dma_prep_dma_memcpy(
 
 	for (offset = 0, i = 0; offset < len; offset += xfer_count, i++) {
 		xfer_count = min_t(size_t, len - offset,
-				   STM32_DMA_MAX_DATA_ITEMS);
+				   STM32_DMA_ALIGNED_MAX_DATA_ITEMS);
 
 		/* Compute best burst size */
 		max_width = DMA_SLAVE_BUSWIDTH_1_BYTE;
-- 
2.7.4

[PATCH v1 6/8] dmaengine: stm32-dma: properly mask irq bits

[Pierre-Yves MORDRET]

A single register of the controller holds the information for four dma
channels.
The functions stm32_dma_irq_status() don't mask the relevant bits after
the shift, thus adjacent channel's status is also reported in the returned
value.
Fixed by masking the value before returning it.

Similarly, the function stm32_dma_irq_clear() don't mask the input value
before shifting it, thus an incorrect input value could disable the
interrupts of adjacent channels.
Fixed by masking the input value before using it.

Signed-off-by: Pierre-Yves MORDRET <pierre-yves.mordret@st.com>
Signed-off-by: Antonio Borneo <borneo.antonio@gmail.com>
---
  Version history:
    v1:
       * Initial
---
---
 drivers/dma/stm32-dma.c | 7 ++++++-
 1 file changed, 6 insertions(+), 1 deletion(-)

diff --git a/drivers/dma/stm32-dma.c b/drivers/dma/stm32-dma.c
index f9d3c84..a11cbee 100644
--- a/drivers/dma/stm32-dma.c
+++ b/drivers/dma/stm32-dma.c
@@ -38,6 +38,10 @@
 #define STM32_DMA_TEI			BIT(3) /* Transfer Error Interrupt */
 #define STM32_DMA_DMEI			BIT(2) /* Direct Mode Error Interrupt */
 #define STM32_DMA_FEI			BIT(0) /* FIFO Error Interrupt */
+#define STM32_DMA_MASKI			(STM32_DMA_TCI \
+					 | STM32_DMA_TEI \
+					 | STM32_DMA_DMEI \
+					 | STM32_DMA_FEI)
 
 /* DMA Stream x Configuration Register */
 #define STM32_DMA_SCR(x)		(0x0010 + 0x18 * (x)) /* x = 0..7 */
@@ -404,7 +408,7 @@ static u32 stm32_dma_irq_status(struct stm32_dma_chan *chan)
 
 	flags = dma_isr >> (((chan->id & 2) << 3) | ((chan->id & 1) * 6));
 
-	return flags;
+	return flags & STM32_DMA_MASKI;
 }
 
 static void stm32_dma_irq_clear(struct stm32_dma_chan *chan, u32 flags)
@@ -419,6 +423,7 @@ static void stm32_dma_irq_clear(struct stm32_dma_chan *chan, u32 flags)
 	 * If (ch % 4) is 2 or 3, left shift the mask by 16 bits.
 	 * If (ch % 4) is 1 or 3, additionally left shift the mask by 6 bits.
 	 */
+	flags &= STM32_DMA_MASKI;
 	dma_ifcr = flags << (((chan->id & 2) << 3) | ((chan->id & 1) * 6));
 
 	if (chan->id & 4)
-- 
2.7.4

[PATCH v1 7/8] dmaengine: stm32-dma: fix incomplete configuration in cyclic mode

[Pierre-Yves MORDRET]

When in cyclic mode, the configuration is updated after having started the
DMA hardware (STM32_DMA_SCR_EN) leading to incomplete configuration of
SMxAR registers.

Signed-off-by: Pierre-Yves MORDRET <pierre-yves.mordret@st.com>
Signed-off-by: Hugues Fruchet <hugues.fruchet@st.com>
---
  Version history:
    v1:
       * Initial
---
---
 drivers/dma/stm32-dma.c | 8 ++++++--
 1 file changed, 6 insertions(+), 2 deletions(-)

diff --git a/drivers/dma/stm32-dma.c b/drivers/dma/stm32-dma.c
index a11cbee..38c545d 100644
--- a/drivers/dma/stm32-dma.c
+++ b/drivers/dma/stm32-dma.c
@@ -538,6 +538,8 @@ static void stm32_dma_dump_reg(struct stm32_dma_chan *chan)
 	dev_dbg(chan2dev(chan), "SFCR:  0x%08x\n", sfcr);
 }
 
+static void stm32_dma_configure_next_sg(struct stm32_dma_chan *chan);
+
 static void stm32_dma_start_transfer(struct stm32_dma_chan *chan)
 {
 	struct stm32_dma_device *dmadev = stm32_dma_get_dev(chan);
@@ -580,6 +582,9 @@ static void stm32_dma_start_transfer(struct stm32_dma_chan *chan)
 	if (status)
 		stm32_dma_irq_clear(chan, status);
 
+	if (chan->desc->cyclic)
+		stm32_dma_configure_next_sg(chan);
+
 	stm32_dma_dump_reg(chan);
 
 	/* Start DMA */
@@ -689,8 +694,7 @@ static void stm32_dma_issue_pending(struct dma_chan *c)
 	if (vchan_issue_pending(&chan->vchan) && !chan->desc && !chan->busy) {
 		dev_dbg(chan2dev(chan), "vchan %p: issued\n", &chan->vchan);
 		stm32_dma_start_transfer(chan);
-		if (chan->desc->cyclic)
-			stm32_dma_configure_next_sg(chan);
+
 	}
 	spin_unlock_irqrestore(&chan->vchan.lock, flags);
 }
-- 
2.7.4

[PATCH v1 8/8] dmaengine: stm32-dma: fix typo and reported checkpatch warnings

[Pierre-Yves MORDRET]

Fix typo in a comment and solved reported checkpatch warnings.

Signed-off-by: Pierre-Yves MORDRET <pierre-yves.mordret@st.com>
---
  Version history:
    v1:
       * Initial
---
---
 drivers/dma/stm32-dma.c | 11 ++++++-----
 1 file changed, 6 insertions(+), 5 deletions(-)

diff --git a/drivers/dma/stm32-dma.c b/drivers/dma/stm32-dma.c
index 38c545d..8c58073 100644
--- a/drivers/dma/stm32-dma.c
+++ b/drivers/dma/stm32-dma.c
@@ -66,7 +66,8 @@
 #define STM32_DMA_SCR_PINC		BIT(9) /* Peripheral increment mode */
 #define STM32_DMA_SCR_CIRC		BIT(8) /* Circular mode */
 #define STM32_DMA_SCR_PFCTRL		BIT(5) /* Peripheral Flow Controller */
-#define STM32_DMA_SCR_TCIE		BIT(4) /* Transfer Cplete Int Enable*/
+#define STM32_DMA_SCR_TCIE		BIT(4) /* Transfer Complete Int Enable
+						*/
 #define STM32_DMA_SCR_TEIE		BIT(2) /* Transfer Error Int Enable */
 #define STM32_DMA_SCR_DMEIE		BIT(1) /* Direct Mode Err Int Enable */
 #define STM32_DMA_SCR_EN		BIT(0) /* Stream Enable */
@@ -1094,7 +1095,7 @@ static enum dma_status stm32_dma_tx_status(struct dma_chan *c,
 	u32 residue = 0;
 
 	status = dma_cookie_status(c, cookie, state);
-	if ((status == DMA_COMPLETE) || (!state))
+	if (status == DMA_COMPLETE || !state)
 		return status;
 
 	spin_lock_irqsave(&chan->vchan.lock, flags);
@@ -1158,7 +1159,7 @@ static void stm32_dma_desc_free(struct virt_dma_desc *vdesc)
 }
 
 static void stm32_dma_set_config(struct stm32_dma_chan *chan,
-			  struct stm32_dma_cfg *cfg)
+				 struct stm32_dma_cfg *cfg)
 {
 	stm32_dma_clear_reg(&chan->chan_reg);
 
@@ -1190,8 +1191,8 @@ static struct dma_chan *stm32_dma_of_xlate(struct of_phandle_args *dma_spec,
 	cfg.stream_config = dma_spec->args[2];
 	cfg.features = dma_spec->args[3];
 
-	if ((cfg.channel_id >= STM32_DMA_MAX_CHANNELS) ||
-	    (cfg.request_line >= STM32_DMA_MAX_REQUEST_ID)) {
+	if (cfg.channel_id >= STM32_DMA_MAX_CHANNELS ||
+	    cfg.request_line >= STM32_DMA_MAX_REQUEST_ID) {
 		dev_err(dev, "Bad channel and/or request id\n");
 		return NULL;
 	}
-- 
2.7.4

Re: [PATCH v1 1/8] dt-bindings: stm32-dma: introduce DMA features bitfield

[Rob Herring]

On Tue, Mar 13, 2018 at 05:42:00PM +0100, Pierre-Yves MORDRET wrote:
> This bitfield intends to address features to be activated within the
> driver. Initially the mask was only meant for FIFO Threshold management.
> Backward compatibility is preserved but the meaning of this field has been
> extended to features instead of only threshold.
> 
> Signed-off-by: Pierre-Yves MORDRET <pierre-yves.mordret@st.com>
> ---
>   Version history:
>     v1:
>        * Initial
> ---
> ---
>  Documentation/devicetree/bindings/dma/stm32-dma.txt | 6 +++---
>  1 file changed, 3 insertions(+), 3 deletions(-)

Reviewed-by: Rob Herring <robh@kernel.org>

Re: [PATCH v1 0/8] Append several fixes and improvements in STM32 DMA

[Vinod Koul]

On Tue, Mar 13, 2018 at 05:41:59PM +0100, Pierre-Yves MORDRET wrote:
> This patchset appends several fixes and some improvements for STM32 DMAv2.
> This includes:
>         * Introduce DMA features bitfield
>         * Threshold manages with bitfield feature
>         * Improve memory burst management
>         * Improve DMA IRQ status handling
>         * Fix max items per transfer to match FIFO Size
>         * Properly mask irq bits to avoid overlaping
>         * Fix incomplete configuration in cyclic mode
>         * Fix typo and reported checkpatch warnings

Applied, thanks

-- 
~Vinod