[PATCH v3 00/13] NVIDIA Tegra APB DMA driver fixes and improvements

[PATCH v3 00/13] NVIDIA Tegra APB DMA driver fixes and improvements

[Dmitry Osipenko]

Hello,

This is series fixes some problems that I spotted recently, secondly the
driver's code gets a cleanup. Please review and apply, thanks in advance!

Changelog:

v3: - In the review comment to v1 Michał Mirosław suggested that "Prevent
      race conditions on channel's freeing" does changes that deserve to
      be separated into two patches. I factored out and improved tasklet
      releasing into this new patch:

        dmaengine: tegra-apb: Clean up tasklet releasing

    - The "Fix use-after-free" patch got an improved commit message.

v2: - I took another look at the driver and spotted few more things that
      could be improved, which resulted in these new patches:

        dmaengine: tegra-apb: Remove runtime PM usage
        dmaengine: tegra-apb: Clean up suspend-resume
        dmaengine: tegra-apb: Add missing of_dma_controller_free
        dmaengine: tegra-apb: Allow to compile as a loadable kernel module
        dmaengine: tegra-apb: Remove MODULE_ALIAS

Dmitry Osipenko (13):
  dmaengine: tegra-apb: Fix use-after-free
  dmaengine: tegra-apb: Implement synchronization callback
  dmaengine: tegra-apb: Prevent race conditions on channel's freeing
  dmaengine: tegra-apb: Clean up tasklet releasing
  dmaengine: tegra-apb: Prevent race conditions of tasklet vs free list
  dmaengine: tegra-apb: Use devm_platform_ioremap_resource
  dmaengine: tegra-apb: Use devm_request_irq
  dmaengine: tegra-apb: Fix coding style problems
  dmaengine: tegra-apb: Remove runtime PM usage
  dmaengine: tegra-apb: Clean up suspend-resume
  dmaengine: tegra-apb: Add missing of_dma_controller_free
  dmaengine: tegra-apb: Allow to compile as a loadable kernel module
  dmaengine: tegra-apb: Remove MODULE_ALIAS

 drivers/dma/Kconfig           |   2 +-
 drivers/dma/tegra20-apb-dma.c | 481 ++++++++++++++++------------------
 2 files changed, 220 insertions(+), 263 deletions(-)

-- 
2.24.0

[PATCH v3 01/13] dmaengine: tegra-apb: Fix use-after-free

[Dmitry Osipenko]

I was doing some experiments with I2C and noticed that Tegra APB DMA
driver crashes sometime after I2C DMA transfer termination. The crash
happens because tegra_dma_terminate_all() bails out immediately if pending
list is empty, thus it doesn't release the half-completed descriptors
which are getting re-used before ISR tasklet kicks-in.

 tegra-i2c 7000c400.i2c: DMA transfer timeout
 elants_i2c 0-0010: elants_i2c_irq: failed to read data: -110
 ------------[ cut here ]------------
 WARNING: CPU: 0 PID: 142 at lib/list_debug.c:45 __list_del_entry_valid+0x45/0xac
 list_del corruption, ddbaac44->next is LIST_POISON1 (00000100)
 Modules linked in:
 CPU: 0 PID: 142 Comm: kworker/0:2 Not tainted 5.5.0-rc2-next-20191220-00175-gc3605715758d-dirty #538
 Hardware name: NVIDIA Tegra SoC (Flattened Device Tree)
 Workqueue: events_freezable_power_ thermal_zone_device_check
 [<c010e5c5>] (unwind_backtrace) from [<c010a1c5>] (show_stack+0x11/0x14)
 [<c010a1c5>] (show_stack) from [<c0973925>] (dump_stack+0x85/0x94)
 [<c0973925>] (dump_stack) from [<c011f529>] (__warn+0xc1/0xc4)
 [<c011f529>] (__warn) from [<c011f7e9>] (warn_slowpath_fmt+0x61/0x78)
 [<c011f7e9>] (warn_slowpath_fmt) from [<c042497d>] (__list_del_entry_valid+0x45/0xac)
 [<c042497d>] (__list_del_entry_valid) from [<c047a87f>] (tegra_dma_tasklet+0x5b/0x154)
 [<c047a87f>] (tegra_dma_tasklet) from [<c0124799>] (tasklet_action_common.constprop.0+0x41/0x7c)
 [<c0124799>] (tasklet_action_common.constprop.0) from [<c01022ab>] (__do_softirq+0xd3/0x2a8)
 [<c01022ab>] (__do_softirq) from [<c0124683>] (irq_exit+0x7b/0x98)
 [<c0124683>] (irq_exit) from [<c0168c19>] (__handle_domain_irq+0x45/0x80)
 [<c0168c19>] (__handle_domain_irq) from [<c043e429>] (gic_handle_irq+0x45/0x7c)
 [<c043e429>] (gic_handle_irq) from [<c0101aa5>] (__irq_svc+0x65/0x94)
 Exception stack(0xde2ebb90 to 0xde2ebbd8)

Cc: <stable@vger.kernel.org>
Signed-off-by: Dmitry Osipenko <digetx@gmail.com>
---
 drivers/dma/tegra20-apb-dma.c | 4 ----
 1 file changed, 4 deletions(-)

diff --git a/drivers/dma/tegra20-apb-dma.c b/drivers/dma/tegra20-apb-dma.c
index 3a45079d11ec..319f31d27014 100644
--- a/drivers/dma/tegra20-apb-dma.c
+++ b/drivers/dma/tegra20-apb-dma.c
@@ -756,10 +756,6 @@ static int tegra_dma_terminate_all(struct dma_chan *dc)
 	bool was_busy;
 
 	spin_lock_irqsave(&tdc->lock, flags);
-	if (list_empty(&tdc->pending_sg_req)) {
-		spin_unlock_irqrestore(&tdc->lock, flags);
-		return 0;
-	}
 
 	if (!tdc->busy)
 		goto skip_dma_stop;
-- 
2.24.0

[PATCH v3 02/13] dmaengine: tegra-apb: Implement synchronization callback

[Dmitry Osipenko]

The ISR tasklet could be kept scheduled after DMA transfer termination,
let's add synchronization callback which blocks until tasklet is finished.

Signed-off-by: Dmitry Osipenko <digetx@gmail.com>
---
 drivers/dma/tegra20-apb-dma.c | 8 ++++++++
 1 file changed, 8 insertions(+)

diff --git a/drivers/dma/tegra20-apb-dma.c b/drivers/dma/tegra20-apb-dma.c
index 319f31d27014..664e9c5df3ba 100644
--- a/drivers/dma/tegra20-apb-dma.c
+++ b/drivers/dma/tegra20-apb-dma.c
@@ -798,6 +798,13 @@ static int tegra_dma_terminate_all(struct dma_chan *dc)
 	return 0;
 }
 
+static void tegra_dma_synchronize(struct dma_chan *dc)
+{
+	struct tegra_dma_channel *tdc = to_tegra_dma_chan(dc);
+
+	tasklet_kill(&tdc->tasklet);
+}
+
 static unsigned int tegra_dma_sg_bytes_xferred(struct tegra_dma_channel *tdc,
 					       struct tegra_dma_sg_req *sg_req)
 {
@@ -1506,6 +1513,7 @@ static int tegra_dma_probe(struct platform_device *pdev)
 	tdma->dma_dev.residue_granularity = DMA_RESIDUE_GRANULARITY_BURST;
 	tdma->dma_dev.device_config = tegra_dma_slave_config;
 	tdma->dma_dev.device_terminate_all = tegra_dma_terminate_all;
+	tdma->dma_dev.device_synchronize = tegra_dma_synchronize;
 	tdma->dma_dev.device_tx_status = tegra_dma_tx_status;
 	tdma->dma_dev.device_issue_pending = tegra_dma_issue_pending;
 
-- 
2.24.0

[PATCH v3 03/13] dmaengine: tegra-apb: Prevent race conditions on channel's freeing

[Dmitry Osipenko]

It's incorrect to check the channel's "busy" state without taking a lock.
That shouldn't cause any real troubles, nevertheless it's always better
not to have any race conditions in the code.

Signed-off-by: Dmitry Osipenko <digetx@gmail.com>
---
 drivers/dma/tegra20-apb-dma.c | 3 +--
 1 file changed, 1 insertion(+), 2 deletions(-)

diff --git a/drivers/dma/tegra20-apb-dma.c b/drivers/dma/tegra20-apb-dma.c
index 664e9c5df3ba..24ad3a5a04e3 100644
--- a/drivers/dma/tegra20-apb-dma.c
+++ b/drivers/dma/tegra20-apb-dma.c
@@ -1294,8 +1294,7 @@ static void tegra_dma_free_chan_resources(struct dma_chan *dc)
 
 	dev_dbg(tdc2dev(tdc), "Freeing channel %d\n", tdc->id);
 
-	if (tdc->busy)
-		tegra_dma_terminate_all(dc);
+	tegra_dma_terminate_all(dc);
 
 	spin_lock_irqsave(&tdc->lock, flags);
 	list_splice_init(&tdc->pending_sg_req, &sg_req_list);
-- 
2.24.0

[PATCH v3 04/13] dmaengine: tegra-apb: Clean up tasklet releasing

[Dmitry Osipenko]

There is no need to kill tasklet when driver's probe fails because tasklet
can't be scheduled at this time. It is also cleaner to kill tasklet on
channel's freeing rather than to kill it on driver's removal, otherwise
tasklet could perform a dummy execution after channel's releasing, which
isn't very nice.

Signed-off-by: Dmitry Osipenko <digetx@gmail.com>
---
 drivers/dma/tegra20-apb-dma.c | 6 +-----
 1 file changed, 1 insertion(+), 5 deletions(-)

diff --git a/drivers/dma/tegra20-apb-dma.c b/drivers/dma/tegra20-apb-dma.c
index 24ad3a5a04e3..1b8a11804962 100644
--- a/drivers/dma/tegra20-apb-dma.c
+++ b/drivers/dma/tegra20-apb-dma.c
@@ -1287,7 +1287,6 @@ static void tegra_dma_free_chan_resources(struct dma_chan *dc)
 	struct tegra_dma_sg_req *sg_req;
 	struct list_head dma_desc_list;
 	struct list_head sg_req_list;
-	unsigned long flags;
 
 	INIT_LIST_HEAD(&dma_desc_list);
 	INIT_LIST_HEAD(&sg_req_list);
@@ -1295,15 +1294,14 @@ static void tegra_dma_free_chan_resources(struct dma_chan *dc)
 	dev_dbg(tdc2dev(tdc), "Freeing channel %d\n", tdc->id);
 
 	tegra_dma_terminate_all(dc);
+	tasklet_kill(&tdc->tasklet);
 
-	spin_lock_irqsave(&tdc->lock, flags);
 	list_splice_init(&tdc->pending_sg_req, &sg_req_list);
 	list_splice_init(&tdc->free_sg_req, &sg_req_list);
 	list_splice_init(&tdc->free_dma_desc, &dma_desc_list);
 	INIT_LIST_HEAD(&tdc->cb_desc);
 	tdc->config_init = false;
 	tdc->isr_handler = NULL;
-	spin_unlock_irqrestore(&tdc->lock, flags);
 
 	while (!list_empty(&dma_desc_list)) {
 		dma_desc = list_first_entry(&dma_desc_list,
@@ -1542,7 +1540,6 @@ static int tegra_dma_probe(struct platform_device *pdev)
 		struct tegra_dma_channel *tdc = &tdma->channels[i];
 
 		free_irq(tdc->irq, tdc);
-		tasklet_kill(&tdc->tasklet);
 	}
 
 	pm_runtime_disable(&pdev->dev);
@@ -1562,7 +1559,6 @@ static int tegra_dma_remove(struct platform_device *pdev)
 	for (i = 0; i < tdma->chip_data->nr_channels; ++i) {
 		tdc = &tdma->channels[i];
 		free_irq(tdc->irq, tdc);
-		tasklet_kill(&tdc->tasklet);
 	}
 
 	pm_runtime_disable(&pdev->dev);
-- 
2.24.0

[PATCH v3 05/13] dmaengine: tegra-apb: Prevent race conditions of tasklet vs free list

[Dmitry Osipenko]

The interrupt handler puts a half-completed DMA descriptor on a free list
and then schedules tasklet to process bottom half of the descriptor that
executes client's callback, this creates possibility to pick up the busy
descriptor from the free list. Thus let's disallow descriptor's re-use
until it is fully processed.

Signed-off-by: Dmitry Osipenko <digetx@gmail.com>
---
 drivers/dma/tegra20-apb-dma.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/dma/tegra20-apb-dma.c b/drivers/dma/tegra20-apb-dma.c
index 1b8a11804962..aafad50d075e 100644
--- a/drivers/dma/tegra20-apb-dma.c
+++ b/drivers/dma/tegra20-apb-dma.c
@@ -281,7 +281,7 @@ static struct tegra_dma_desc *tegra_dma_desc_get(
 
 	/* Do not allocate if desc are waiting for ack */
 	list_for_each_entry(dma_desc, &tdc->free_dma_desc, node) {
-		if (async_tx_test_ack(&dma_desc->txd)) {
+		if (async_tx_test_ack(&dma_desc->txd) && !dma_desc->cb_count) {
 			list_del(&dma_desc->node);
 			spin_unlock_irqrestore(&tdc->lock, flags);
 			dma_desc->txd.flags = 0;
-- 
2.24.0

[PATCH v3 06/13] dmaengine: tegra-apb: Use devm_platform_ioremap_resource

[Dmitry Osipenko]

Use devm_platform_ioremap_resource to keep code cleaner a tad.

Signed-off-by: Dmitry Osipenko <digetx@gmail.com>
---
 drivers/dma/tegra20-apb-dma.c | 3 +--
 1 file changed, 1 insertion(+), 2 deletions(-)

diff --git a/drivers/dma/tegra20-apb-dma.c b/drivers/dma/tegra20-apb-dma.c
index aafad50d075e..f44291207928 100644
--- a/drivers/dma/tegra20-apb-dma.c
+++ b/drivers/dma/tegra20-apb-dma.c
@@ -1402,8 +1402,7 @@ static int tegra_dma_probe(struct platform_device *pdev)
 	tdma->chip_data = cdata;
 	platform_set_drvdata(pdev, tdma);
 
-	res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
-	tdma->base_addr = devm_ioremap_resource(&pdev->dev, res);
+	tdma->base_addr = devm_platform_ioremap_resource(pdev, 0);
 	if (IS_ERR(tdma->base_addr))
 		return PTR_ERR(tdma->base_addr);
 
-- 
2.24.0

[PATCH v3 07/13] dmaengine: tegra-apb: Use devm_request_irq

[Dmitry Osipenko]

Use resource-managed variant of request_irq for brevity.

Signed-off-by: Dmitry Osipenko <digetx@gmail.com>
---
 drivers/dma/tegra20-apb-dma.c | 35 +++++++++++------------------------
 1 file changed, 11 insertions(+), 24 deletions(-)

diff --git a/drivers/dma/tegra20-apb-dma.c b/drivers/dma/tegra20-apb-dma.c
index f44291207928..dff21e80ffa4 100644
--- a/drivers/dma/tegra20-apb-dma.c
+++ b/drivers/dma/tegra20-apb-dma.c
@@ -182,7 +182,6 @@ struct tegra_dma_channel {
 	char			name[12];
 	bool			config_init;
 	int			id;
-	int			irq;
 	void __iomem		*chan_addr;
 	spinlock_t		lock;
 	bool			busy;
@@ -1380,7 +1379,6 @@ static const struct tegra_dma_chip_data tegra148_dma_chip_data = {
 
 static int tegra_dma_probe(struct platform_device *pdev)
 {
-	struct resource *res;
 	struct tegra_dma *tdma;
 	int ret;
 	int i;
@@ -1446,25 +1444,27 @@ static int tegra_dma_probe(struct platform_device *pdev)
 	INIT_LIST_HEAD(&tdma->dma_dev.channels);
 	for (i = 0; i < cdata->nr_channels; i++) {
 		struct tegra_dma_channel *tdc = &tdma->channels[i];
+		int irq;
 
 		tdc->chan_addr = tdma->base_addr +
 				 TEGRA_APBDMA_CHANNEL_BASE_ADD_OFFSET +
 				 (i * cdata->channel_reg_size);
 
-		res = platform_get_resource(pdev, IORESOURCE_IRQ, i);
-		if (!res) {
-			ret = -EINVAL;
+		irq = platform_get_irq(pdev, i);
+		if (irq < 0) {
+			ret = irq;
 			dev_err(&pdev->dev, "No irq resource for chan %d\n", i);
-			goto err_irq;
+			goto err_pm_disable;
 		}
-		tdc->irq = res->start;
+
 		snprintf(tdc->name, sizeof(tdc->name), "apbdma.%d", i);
-		ret = request_irq(tdc->irq, tegra_dma_isr, 0, tdc->name, tdc);
+		ret = devm_request_irq(&pdev->dev, irq, tegra_dma_isr, 0,
+				       tdc->name, tdc);
 		if (ret) {
 			dev_err(&pdev->dev,
 				"request_irq failed with err %d channel %d\n",
 				ret, i);
-			goto err_irq;
+			goto err_pm_disable;
 		}
 
 		tdc->dma_chan.device = &tdma->dma_dev;
@@ -1517,7 +1517,7 @@ static int tegra_dma_probe(struct platform_device *pdev)
 	if (ret < 0) {
 		dev_err(&pdev->dev,
 			"Tegra20 APB DMA driver registration failed %d\n", ret);
-		goto err_irq;
+		goto err_pm_disable;
 	}
 
 	ret = of_dma_controller_register(pdev->dev.of_node,
@@ -1534,13 +1534,7 @@ static int tegra_dma_probe(struct platform_device *pdev)
 
 err_unregister_dma_dev:
 	dma_async_device_unregister(&tdma->dma_dev);
-err_irq:
-	while (--i >= 0) {
-		struct tegra_dma_channel *tdc = &tdma->channels[i];
-
-		free_irq(tdc->irq, tdc);
-	}
-
+err_pm_disable:
 	pm_runtime_disable(&pdev->dev);
 	if (!pm_runtime_status_suspended(&pdev->dev))
 		tegra_dma_runtime_suspend(&pdev->dev);
@@ -1550,16 +1544,9 @@ static int tegra_dma_probe(struct platform_device *pdev)
 static int tegra_dma_remove(struct platform_device *pdev)
 {
 	struct tegra_dma *tdma = platform_get_drvdata(pdev);
-	int i;
-	struct tegra_dma_channel *tdc;
 
 	dma_async_device_unregister(&tdma->dma_dev);
 
-	for (i = 0; i < tdma->chip_data->nr_channels; ++i) {
-		tdc = &tdma->channels[i];
-		free_irq(tdc->irq, tdc);
-	}
-
 	pm_runtime_disable(&pdev->dev);
 	if (!pm_runtime_status_suspended(&pdev->dev))
 		tegra_dma_runtime_suspend(&pdev->dev);
-- 
2.24.0

[PATCH v3 08/13] dmaengine: tegra-apb: Fix coding style problems

[Dmitry Osipenko]

This patch fixes few dozens of coding style problems reported by
checkpatch and prettifies code where makes sense.

Signed-off-by: Dmitry Osipenko <digetx@gmail.com>
---
 drivers/dma/tegra20-apb-dma.c | 276 ++++++++++++++++++----------------
 1 file changed, 144 insertions(+), 132 deletions(-)

diff --git a/drivers/dma/tegra20-apb-dma.c b/drivers/dma/tegra20-apb-dma.c
index dff21e80ffa4..804007cbd6f0 100644
--- a/drivers/dma/tegra20-apb-dma.c
+++ b/drivers/dma/tegra20-apb-dma.c
@@ -59,7 +59,7 @@
 #define TEGRA_APBDMA_STATUS_COUNT_MASK		0xFFFC
 
 #define TEGRA_APBDMA_CHAN_CSRE			0x00C
-#define TEGRA_APBDMA_CHAN_CSRE_PAUSE		(1 << 31)
+#define TEGRA_APBDMA_CHAN_CSRE_PAUSE		BIT(31)
 
 /* AHB memory address */
 #define TEGRA_APBDMA_CHAN_AHBPTR		0x010
@@ -120,21 +120,21 @@ struct tegra_dma;
  * @support_separate_wcount_reg: Support separate word count register.
  */
 struct tegra_dma_chip_data {
-	int nr_channels;
-	int channel_reg_size;
-	int max_dma_count;
+	unsigned int nr_channels;
+	unsigned int channel_reg_size;
+	unsigned int max_dma_count;
 	bool support_channel_pause;
 	bool support_separate_wcount_reg;
 };
 
 /* DMA channel registers */
 struct tegra_dma_channel_regs {
-	unsigned long	csr;
-	unsigned long	ahb_ptr;
-	unsigned long	apb_ptr;
-	unsigned long	ahb_seq;
-	unsigned long	apb_seq;
-	unsigned long	wcount;
+	u32 csr;
+	u32 ahb_ptr;
+	u32 apb_ptr;
+	u32 ahb_seq;
+	u32 apb_seq;
+	u32 wcount;
 };
 
 /*
@@ -168,7 +168,7 @@ struct tegra_dma_desc {
 	struct list_head		node;
 	struct list_head		tx_list;
 	struct list_head		cb_node;
-	int				cb_count;
+	unsigned int			cb_count;
 };
 
 struct tegra_dma_channel;
@@ -181,7 +181,7 @@ struct tegra_dma_channel {
 	struct dma_chan		dma_chan;
 	char			name[12];
 	bool			config_init;
-	int			id;
+	unsigned int		id;
 	void __iomem		*chan_addr;
 	spinlock_t		lock;
 	bool			busy;
@@ -201,7 +201,7 @@ struct tegra_dma_channel {
 	/* Channel-slave specific configuration */
 	unsigned int slave_id;
 	struct dma_slave_config dma_sconfig;
-	struct tegra_dma_channel_regs	channel_reg;
+	struct tegra_dma_channel_regs channel_reg;
 };
 
 /* tegra_dma: Tegra DMA specific information */
@@ -239,7 +239,7 @@ static inline u32 tdma_read(struct tegra_dma *tdma, u32 reg)
 }
 
 static inline void tdc_write(struct tegra_dma_channel *tdc,
-		u32 reg, u32 val)
+			     u32 reg, u32 val)
 {
 	writel(val, tdc->chan_addr + reg);
 }
@@ -254,8 +254,8 @@ static inline struct tegra_dma_channel *to_tegra_dma_chan(struct dma_chan *dc)
 	return container_of(dc, struct tegra_dma_channel, dma_chan);
 }
 
-static inline struct tegra_dma_desc *txd_to_tegra_dma_desc(
-		struct dma_async_tx_descriptor *td)
+static inline struct tegra_dma_desc *
+txd_to_tegra_dma_desc(struct dma_async_tx_descriptor *td)
 {
 	return container_of(td, struct tegra_dma_desc, txd);
 }
@@ -270,8 +270,7 @@ static int tegra_dma_runtime_suspend(struct device *dev);
 static int tegra_dma_runtime_resume(struct device *dev);
 
 /* Get DMA desc from free list, if not there then allocate it.  */
-static struct tegra_dma_desc *tegra_dma_desc_get(
-		struct tegra_dma_channel *tdc)
+static struct tegra_dma_desc *tegra_dma_desc_get(struct tegra_dma_channel *tdc)
 {
 	struct tegra_dma_desc *dma_desc;
 	unsigned long flags;
@@ -298,11 +297,12 @@ static struct tegra_dma_desc *tegra_dma_desc_get(
 	dma_async_tx_descriptor_init(&dma_desc->txd, &tdc->dma_chan);
 	dma_desc->txd.tx_submit = tegra_dma_tx_submit;
 	dma_desc->txd.flags = 0;
+
 	return dma_desc;
 }
 
 static void tegra_dma_desc_put(struct tegra_dma_channel *tdc,
-		struct tegra_dma_desc *dma_desc)
+			       struct tegra_dma_desc *dma_desc)
 {
 	unsigned long flags;
 
@@ -313,29 +313,29 @@ static void tegra_dma_desc_put(struct tegra_dma_channel *tdc,
 	spin_unlock_irqrestore(&tdc->lock, flags);
 }
 
-static struct tegra_dma_sg_req *tegra_dma_sg_req_get(
-		struct tegra_dma_channel *tdc)
+static struct tegra_dma_sg_req *
+tegra_dma_sg_req_get(struct tegra_dma_channel *tdc)
 {
-	struct tegra_dma_sg_req *sg_req = NULL;
+	struct tegra_dma_sg_req *sg_req;
 	unsigned long flags;
 
 	spin_lock_irqsave(&tdc->lock, flags);
 	if (!list_empty(&tdc->free_sg_req)) {
-		sg_req = list_first_entry(&tdc->free_sg_req,
-					typeof(*sg_req), node);
+		sg_req = list_first_entry(&tdc->free_sg_req, typeof(*sg_req),
+					  node);
 		list_del(&sg_req->node);
 		spin_unlock_irqrestore(&tdc->lock, flags);
 		return sg_req;
 	}
 	spin_unlock_irqrestore(&tdc->lock, flags);
 
-	sg_req = kzalloc(sizeof(struct tegra_dma_sg_req), GFP_NOWAIT);
+	sg_req = kzalloc(sizeof(*sg_req), GFP_NOWAIT);
 
 	return sg_req;
 }
 
 static int tegra_dma_slave_config(struct dma_chan *dc,
-		struct dma_slave_config *sconfig)
+				  struct dma_slave_config *sconfig)
 {
 	struct tegra_dma_channel *tdc = to_tegra_dma_chan(dc);
 
@@ -352,11 +352,12 @@ static int tegra_dma_slave_config(struct dma_chan *dc,
 		tdc->slave_id = sconfig->slave_id;
 	}
 	tdc->config_init = true;
+
 	return 0;
 }
 
 static void tegra_dma_global_pause(struct tegra_dma_channel *tdc,
-	bool wait_for_burst_complete)
+				   bool wait_for_burst_complete)
 {
 	struct tegra_dma *tdma = tdc->tdma;
 
@@ -391,13 +392,13 @@ static void tegra_dma_global_resume(struct tegra_dma_channel *tdc)
 }
 
 static void tegra_dma_pause(struct tegra_dma_channel *tdc,
-	bool wait_for_burst_complete)
+			    bool wait_for_burst_complete)
 {
 	struct tegra_dma *tdma = tdc->tdma;
 
 	if (tdma->chip_data->support_channel_pause) {
 		tdc_write(tdc, TEGRA_APBDMA_CHAN_CSRE,
-				TEGRA_APBDMA_CHAN_CSRE_PAUSE);
+			  TEGRA_APBDMA_CHAN_CSRE_PAUSE);
 		if (wait_for_burst_complete)
 			udelay(TEGRA_APBDMA_BURST_COMPLETE_TIME);
 	} else {
@@ -409,17 +410,15 @@ static void tegra_dma_resume(struct tegra_dma_channel *tdc)
 {
 	struct tegra_dma *tdma = tdc->tdma;
 
-	if (tdma->chip_data->support_channel_pause) {
+	if (tdma->chip_data->support_channel_pause)
 		tdc_write(tdc, TEGRA_APBDMA_CHAN_CSRE, 0);
-	} else {
+	else
 		tegra_dma_global_resume(tdc);
-	}
 }
 
 static void tegra_dma_stop(struct tegra_dma_channel *tdc)
 {
-	u32 csr;
-	u32 status;
+	u32 csr, status;
 
 	/* Disable interrupts */
 	csr = tdc_read(tdc, TEGRA_APBDMA_CHAN_CSR);
@@ -440,7 +439,7 @@ static void tegra_dma_stop(struct tegra_dma_channel *tdc)
 }
 
 static void tegra_dma_start(struct tegra_dma_channel *tdc,
-		struct tegra_dma_sg_req *sg_req)
+			    struct tegra_dma_sg_req *sg_req)
 {
 	struct tegra_dma_channel_regs *ch_regs = &sg_req->ch_regs;
 
@@ -454,11 +453,11 @@ static void tegra_dma_start(struct tegra_dma_channel *tdc,
 
 	/* Start DMA */
 	tdc_write(tdc, TEGRA_APBDMA_CHAN_CSR,
-				ch_regs->csr | TEGRA_APBDMA_CSR_ENB);
+		  ch_regs->csr | TEGRA_APBDMA_CSR_ENB);
 }
 
 static void tegra_dma_configure_for_next(struct tegra_dma_channel *tdc,
-		struct tegra_dma_sg_req *nsg_req)
+					 struct tegra_dma_sg_req *nsg_req)
 {
 	unsigned long status;
 
@@ -492,9 +491,9 @@ static void tegra_dma_configure_for_next(struct tegra_dma_channel *tdc,
 	tdc_write(tdc, TEGRA_APBDMA_CHAN_AHBPTR, nsg_req->ch_regs.ahb_ptr);
 	if (tdc->tdma->chip_data->support_separate_wcount_reg)
 		tdc_write(tdc, TEGRA_APBDMA_CHAN_WCOUNT,
-						nsg_req->ch_regs.wcount);
+			  nsg_req->ch_regs.wcount);
 	tdc_write(tdc, TEGRA_APBDMA_CHAN_CSR,
-				nsg_req->ch_regs.csr | TEGRA_APBDMA_CSR_ENB);
+		  nsg_req->ch_regs.csr | TEGRA_APBDMA_CSR_ENB);
 	nsg_req->configured = true;
 	nsg_req->words_xferred = 0;
 
@@ -508,8 +507,7 @@ static void tdc_start_head_req(struct tegra_dma_channel *tdc)
 	if (list_empty(&tdc->pending_sg_req))
 		return;
 
-	sg_req = list_first_entry(&tdc->pending_sg_req,
-					typeof(*sg_req), node);
+	sg_req = list_first_entry(&tdc->pending_sg_req, typeof(*sg_req), node);
 	tegra_dma_start(tdc, sg_req);
 	sg_req->configured = true;
 	sg_req->words_xferred = 0;
@@ -518,34 +516,35 @@ static void tdc_start_head_req(struct tegra_dma_channel *tdc)
 
 static void tdc_configure_next_head_desc(struct tegra_dma_channel *tdc)
 {
-	struct tegra_dma_sg_req *hsgreq;
-	struct tegra_dma_sg_req *hnsgreq;
+	struct tegra_dma_sg_req *hsgreq, *hnsgreq;
 
 	if (list_empty(&tdc->pending_sg_req))
 		return;
 
 	hsgreq = list_first_entry(&tdc->pending_sg_req, typeof(*hsgreq), node);
 	if (!list_is_last(&hsgreq->node, &tdc->pending_sg_req)) {
-		hnsgreq = list_first_entry(&hsgreq->node,
-					typeof(*hnsgreq), node);
+		hnsgreq = list_first_entry(&hsgreq->node, typeof(*hnsgreq),
+					   node);
 		tegra_dma_configure_for_next(tdc, hnsgreq);
 	}
 }
 
-static inline int get_current_xferred_count(struct tegra_dma_channel *tdc,
-	struct tegra_dma_sg_req *sg_req, unsigned long status)
+static inline unsigned int
+get_current_xferred_count(struct tegra_dma_channel *tdc,
+			  struct tegra_dma_sg_req *sg_req,
+			  unsigned long status)
 {
 	return sg_req->req_len - (status & TEGRA_APBDMA_STATUS_COUNT_MASK) - 4;
 }
 
 static void tegra_dma_abort_all(struct tegra_dma_channel *tdc)
 {
-	struct tegra_dma_sg_req *sgreq;
 	struct tegra_dma_desc *dma_desc;
+	struct tegra_dma_sg_req *sgreq;
 
 	while (!list_empty(&tdc->pending_sg_req)) {
-		sgreq = list_first_entry(&tdc->pending_sg_req,
-						typeof(*sgreq), node);
+		sgreq = list_first_entry(&tdc->pending_sg_req, typeof(*sgreq),
+					 node);
 		list_move_tail(&sgreq->node, &tdc->free_sg_req);
 		if (sgreq->last_sg) {
 			dma_desc = sgreq->dma_desc;
@@ -555,7 +554,7 @@ static void tegra_dma_abort_all(struct tegra_dma_channel *tdc)
 			/* Add in cb list if it is not there. */
 			if (!dma_desc->cb_count)
 				list_add_tail(&dma_desc->cb_node,
-							&tdc->cb_desc);
+					      &tdc->cb_desc);
 			dma_desc->cb_count++;
 		}
 	}
@@ -563,9 +562,10 @@ static void tegra_dma_abort_all(struct tegra_dma_channel *tdc)
 }
 
 static bool handle_continuous_head_request(struct tegra_dma_channel *tdc,
-		struct tegra_dma_sg_req *last_sg_req, bool to_terminate)
+					   struct tegra_dma_sg_req *last_sg_req,
+					   bool to_terminate)
 {
-	struct tegra_dma_sg_req *hsgreq = NULL;
+	struct tegra_dma_sg_req *hsgreq;
 
 	if (list_empty(&tdc->pending_sg_req)) {
 		dev_err(tdc2dev(tdc), "DMA is running without req\n");
@@ -589,14 +589,15 @@ static bool handle_continuous_head_request(struct tegra_dma_channel *tdc,
 	/* Configure next request */
 	if (!to_terminate)
 		tdc_configure_next_head_desc(tdc);
+
 	return true;
 }
 
 static void handle_once_dma_done(struct tegra_dma_channel *tdc,
-	bool to_terminate)
+				 bool to_terminate)
 {
-	struct tegra_dma_sg_req *sgreq;
 	struct tegra_dma_desc *dma_desc;
+	struct tegra_dma_sg_req *sgreq;
 
 	tdc->busy = false;
 	sgreq = list_first_entry(&tdc->pending_sg_req, typeof(*sgreq), node);
@@ -622,10 +623,10 @@ static void handle_once_dma_done(struct tegra_dma_channel *tdc,
 }
 
 static void handle_cont_sngl_cycle_dma_done(struct tegra_dma_channel *tdc,
-		bool to_terminate)
+					    bool to_terminate)
 {
-	struct tegra_dma_sg_req *sgreq;
 	struct tegra_dma_desc *dma_desc;
+	struct tegra_dma_sg_req *sgreq;
 	bool st;
 
 	sgreq = list_first_entry(&tdc->pending_sg_req, typeof(*sgreq), node);
@@ -657,13 +658,13 @@ static void tegra_dma_tasklet(unsigned long data)
 	struct tegra_dma_channel *tdc = (struct tegra_dma_channel *)data;
 	struct dmaengine_desc_callback cb;
 	struct tegra_dma_desc *dma_desc;
+	unsigned int cb_count;
 	unsigned long flags;
-	int cb_count;
 
 	spin_lock_irqsave(&tdc->lock, flags);
 	while (!list_empty(&tdc->cb_desc)) {
-		dma_desc  = list_first_entry(&tdc->cb_desc,
-					typeof(*dma_desc), cb_node);
+		dma_desc = list_first_entry(&tdc->cb_desc, typeof(*dma_desc),
+					    cb_node);
 		list_del(&dma_desc->cb_node);
 		dmaengine_desc_get_callback(&dma_desc->txd, &cb);
 		cb_count = dma_desc->cb_count;
@@ -681,8 +682,8 @@ static void tegra_dma_tasklet(unsigned long data)
 static irqreturn_t tegra_dma_isr(int irq, void *dev_id)
 {
 	struct tegra_dma_channel *tdc = dev_id;
-	unsigned long status;
 	unsigned long flags;
+	u32 status;
 
 	spin_lock_irqsave(&tdc->lock, flags);
 
@@ -697,8 +698,9 @@ static irqreturn_t tegra_dma_isr(int irq, void *dev_id)
 	}
 
 	spin_unlock_irqrestore(&tdc->lock, flags);
-	dev_info(tdc2dev(tdc),
-		"Interrupt already served status 0x%08lx\n", status);
+	dev_info(tdc2dev(tdc), "Interrupt already served status 0x%08x\n",
+		 status);
+
 	return IRQ_NONE;
 }
 
@@ -714,6 +716,7 @@ static dma_cookie_t tegra_dma_tx_submit(struct dma_async_tx_descriptor *txd)
 	cookie = dma_cookie_assign(&dma_desc->txd);
 	list_splice_tail_init(&dma_desc->tx_list, &tdc->pending_sg_req);
 	spin_unlock_irqrestore(&tdc->lock, flags);
+
 	return cookie;
 }
 
@@ -747,11 +750,10 @@ static void tegra_dma_issue_pending(struct dma_chan *dc)
 static int tegra_dma_terminate_all(struct dma_chan *dc)
 {
 	struct tegra_dma_channel *tdc = to_tegra_dma_chan(dc);
-	struct tegra_dma_sg_req *sgreq;
 	struct tegra_dma_desc *dma_desc;
+	struct tegra_dma_sg_req *sgreq;
 	unsigned long flags;
-	unsigned long status;
-	unsigned long wcount;
+	u32 status, wcount;
 	bool was_busy;
 
 	spin_lock_irqsave(&tdc->lock, flags);
@@ -777,8 +779,8 @@ static int tegra_dma_terminate_all(struct dma_chan *dc)
 	tegra_dma_stop(tdc);
 
 	if (!list_empty(&tdc->pending_sg_req) && was_busy) {
-		sgreq = list_first_entry(&tdc->pending_sg_req,
-					typeof(*sgreq), node);
+		sgreq = list_first_entry(&tdc->pending_sg_req, typeof(*sgreq),
+					 node);
 		sgreq->dma_desc->bytes_transferred +=
 				get_current_xferred_count(tdc, sgreq, wcount);
 	}
@@ -788,12 +790,13 @@ static int tegra_dma_terminate_all(struct dma_chan *dc)
 	tegra_dma_abort_all(tdc);
 
 	while (!list_empty(&tdc->cb_desc)) {
-		dma_desc  = list_first_entry(&tdc->cb_desc,
-					typeof(*dma_desc), cb_node);
+		dma_desc = list_first_entry(&tdc->cb_desc, typeof(*dma_desc),
+					    cb_node);
 		list_del(&dma_desc->cb_node);
 		dma_desc->cb_count = 0;
 	}
 	spin_unlock_irqrestore(&tdc->lock, flags);
+
 	return 0;
 }
 
@@ -807,7 +810,7 @@ static void tegra_dma_synchronize(struct dma_chan *dc)
 static unsigned int tegra_dma_sg_bytes_xferred(struct tegra_dma_channel *tdc,
 					       struct tegra_dma_sg_req *sg_req)
 {
-	unsigned long status, wcount = 0;
+	u32 status, wcount = 0;
 
 	if (!list_is_first(&sg_req->node, &tdc->pending_sg_req))
 		return 0;
@@ -864,7 +867,8 @@ static unsigned int tegra_dma_sg_bytes_xferred(struct tegra_dma_channel *tdc,
 }
 
 static enum dma_status tegra_dma_tx_status(struct dma_chan *dc,
-	dma_cookie_t cookie, struct dma_tx_state *txstate)
+					   dma_cookie_t cookie,
+					   struct dma_tx_state *txstate)
 {
 	struct tegra_dma_channel *tdc = to_tegra_dma_chan(dc);
 	struct tegra_dma_desc *dma_desc;
@@ -911,11 +915,12 @@ static enum dma_status tegra_dma_tx_status(struct dma_chan *dc,
 
 	trace_tegra_dma_tx_status(&tdc->dma_chan, cookie, txstate);
 	spin_unlock_irqrestore(&tdc->lock, flags);
+
 	return ret;
 }
 
-static inline int get_bus_width(struct tegra_dma_channel *tdc,
-		enum dma_slave_buswidth slave_bw)
+static inline unsigned int get_bus_width(struct tegra_dma_channel *tdc,
+					 enum dma_slave_buswidth slave_bw)
 {
 	switch (slave_bw) {
 	case DMA_SLAVE_BUSWIDTH_1_BYTE:
@@ -928,16 +933,17 @@ static inline int get_bus_width(struct tegra_dma_channel *tdc,
 		return TEGRA_APBDMA_APBSEQ_BUS_WIDTH_64;
 	default:
 		dev_warn(tdc2dev(tdc),
-			"slave bw is not supported, using 32bits\n");
+			 "slave bw is not supported, using 32bits\n");
 		return TEGRA_APBDMA_APBSEQ_BUS_WIDTH_32;
 	}
 }
 
-static inline int get_burst_size(struct tegra_dma_channel *tdc,
-	u32 burst_size, enum dma_slave_buswidth slave_bw, int len)
+static inline unsigned int get_burst_size(struct tegra_dma_channel *tdc,
+					  u32 burst_size,
+					  enum dma_slave_buswidth slave_bw,
+					  u32 len)
 {
-	int burst_byte;
-	int burst_ahb_width;
+	unsigned int burst_byte, burst_ahb_width;
 
 	/*
 	 * burst_size from client is in terms of the bus_width.
@@ -964,9 +970,12 @@ static inline int get_burst_size(struct tegra_dma_channel *tdc,
 }
 
 static int get_transfer_param(struct tegra_dma_channel *tdc,
-	enum dma_transfer_direction direction, unsigned long *apb_addr,
-	unsigned long *apb_seq,	unsigned long *csr, unsigned int *burst_size,
-	enum dma_slave_buswidth *slave_bw)
+			      enum dma_transfer_direction direction,
+			      u32 *apb_addr,
+			      u32 *apb_seq,
+			      u32 *csr,
+			      unsigned int *burst_size,
+			      enum dma_slave_buswidth *slave_bw)
 {
 	switch (direction) {
 	case DMA_MEM_TO_DEV:
@@ -987,13 +996,15 @@ static int get_transfer_param(struct tegra_dma_channel *tdc,
 
 	default:
 		dev_err(tdc2dev(tdc), "DMA direction is not supported\n");
-		return -EINVAL;
+		break;
 	}
+
 	return -EINVAL;
 }
 
 static void tegra_dma_prep_wcount(struct tegra_dma_channel *tdc,
-	struct tegra_dma_channel_regs *ch_regs, u32 len)
+				  struct tegra_dma_channel_regs *ch_regs,
+				  u32 len)
 {
 	u32 len_field = (len - 4) & 0xFFFC;
 
@@ -1003,20 +1014,23 @@ static void tegra_dma_prep_wcount(struct tegra_dma_channel *tdc,
 		ch_regs->csr |= len_field;
 }
 
-static struct dma_async_tx_descriptor *tegra_dma_prep_slave_sg(
-	struct dma_chan *dc, struct scatterlist *sgl, unsigned int sg_len,
-	enum dma_transfer_direction direction, unsigned long flags,
-	void *context)
+static struct dma_async_tx_descriptor *
+tegra_dma_prep_slave_sg(struct dma_chan *dc,
+			struct scatterlist *sgl,
+			unsigned int sg_len,
+			enum dma_transfer_direction direction,
+			unsigned long flags,
+			void *context)
 {
 	struct tegra_dma_channel *tdc = to_tegra_dma_chan(dc);
+	struct tegra_dma_sg_req *sg_req = NULL;
+	u32 csr, ahb_seq, apb_ptr, apb_seq;
+	enum dma_slave_buswidth slave_bw;
 	struct tegra_dma_desc *dma_desc;
-	unsigned int i;
-	struct scatterlist *sg;
-	unsigned long csr, ahb_seq, apb_ptr, apb_seq;
 	struct list_head req_list;
-	struct tegra_dma_sg_req  *sg_req = NULL;
-	u32 burst_size;
-	enum dma_slave_buswidth slave_bw;
+	struct scatterlist *sg;
+	unsigned int burst_size;
+	unsigned int i;
 
 	if (!tdc->config_init) {
 		dev_err(tdc2dev(tdc), "DMA channel is not configured\n");
@@ -1028,7 +1042,7 @@ static struct dma_async_tx_descriptor *tegra_dma_prep_slave_sg(
 	}
 
 	if (get_transfer_param(tdc, direction, &apb_ptr, &apb_seq, &csr,
-				&burst_size, &slave_bw) < 0)
+			       &burst_size, &slave_bw) < 0)
 		return NULL;
 
 	INIT_LIST_HEAD(&req_list);
@@ -1074,7 +1088,7 @@ static struct dma_async_tx_descriptor *tegra_dma_prep_slave_sg(
 		len = sg_dma_len(sg);
 
 		if ((len & 3) || (mem & 3) ||
-				(len > tdc->tdma->chip_data->max_dma_count)) {
+		    len > tdc->tdma->chip_data->max_dma_count) {
 			dev_err(tdc2dev(tdc),
 				"DMA length/memory address is not supported\n");
 			tegra_dma_desc_put(tdc, dma_desc);
@@ -1126,20 +1140,21 @@ static struct dma_async_tx_descriptor *tegra_dma_prep_slave_sg(
 	return &dma_desc->txd;
 }
 
-static struct dma_async_tx_descriptor *tegra_dma_prep_dma_cyclic(
-	struct dma_chan *dc, dma_addr_t buf_addr, size_t buf_len,
-	size_t period_len, enum dma_transfer_direction direction,
-	unsigned long flags)
+static struct dma_async_tx_descriptor *
+tegra_dma_prep_dma_cyclic(struct dma_chan *dc, dma_addr_t buf_addr,
+			  size_t buf_len,
+			  size_t period_len,
+			  enum dma_transfer_direction direction,
+			  unsigned long flags)
 {
 	struct tegra_dma_channel *tdc = to_tegra_dma_chan(dc);
-	struct tegra_dma_desc *dma_desc = NULL;
 	struct tegra_dma_sg_req *sg_req = NULL;
-	unsigned long csr, ahb_seq, apb_ptr, apb_seq;
-	int len;
-	size_t remain_len;
-	dma_addr_t mem = buf_addr;
-	u32 burst_size;
+	u32 csr, ahb_seq, apb_ptr, apb_seq;
 	enum dma_slave_buswidth slave_bw;
+	struct tegra_dma_desc *dma_desc;
+	dma_addr_t mem = buf_addr;
+	unsigned int burst_size;
+	size_t len, remain_len;
 
 	if (!buf_len || !period_len) {
 		dev_err(tdc2dev(tdc), "Invalid buffer/period len\n");
@@ -1173,13 +1188,13 @@ static struct dma_async_tx_descriptor *tegra_dma_prep_dma_cyclic(
 
 	len = period_len;
 	if ((len & 3) || (buf_addr & 3) ||
-			(len > tdc->tdma->chip_data->max_dma_count)) {
+	    len > tdc->tdma->chip_data->max_dma_count) {
 		dev_err(tdc2dev(tdc), "Req len/mem address is not correct\n");
 		return NULL;
 	}
 
 	if (get_transfer_param(tdc, direction, &apb_ptr, &apb_seq, &csr,
-				&burst_size, &slave_bw) < 0)
+			       &burst_size, &slave_bw) < 0)
 		return NULL;
 
 	ahb_seq = TEGRA_APBDMA_AHBSEQ_INTR_ENB;
@@ -1269,7 +1284,6 @@ static int tegra_dma_alloc_chan_resources(struct dma_chan *dc)
 	int ret;
 
 	dma_cookie_init(&tdc->dma_chan);
-	tdc->config_init = false;
 
 	ret = pm_runtime_get_sync(tdma->dev);
 	if (ret < 0)
@@ -1303,8 +1317,8 @@ static void tegra_dma_free_chan_resources(struct dma_chan *dc)
 	tdc->isr_handler = NULL;
 
 	while (!list_empty(&dma_desc_list)) {
-		dma_desc = list_first_entry(&dma_desc_list,
-					typeof(*dma_desc), node);
+		dma_desc = list_first_entry(&dma_desc_list, typeof(*dma_desc),
+					    node);
 		list_del(&dma_desc->node);
 		kfree(dma_desc);
 	}
@@ -1323,8 +1337,8 @@ static struct dma_chan *tegra_dma_of_xlate(struct of_phandle_args *dma_spec,
 					   struct of_dma *ofdma)
 {
 	struct tegra_dma *tdma = ofdma->of_dma_data;
-	struct dma_chan *chan;
 	struct tegra_dma_channel *tdc;
+	struct dma_chan *chan;
 
 	if (dma_spec->args[0] > TEGRA_APBDMA_CSR_REQ_SEL_MASK) {
 		dev_err(tdma->dev, "Invalid slave id: %d\n", dma_spec->args[0]);
@@ -1379,20 +1393,16 @@ static const struct tegra_dma_chip_data tegra148_dma_chip_data = {
 
 static int tegra_dma_probe(struct platform_device *pdev)
 {
+	const struct tegra_dma_chip_data *cdata;
 	struct tegra_dma *tdma;
+	unsigned int i;
+	size_t size;
 	int ret;
-	int i;
-	const struct tegra_dma_chip_data *cdata;
 
 	cdata = of_device_get_match_data(&pdev->dev);
-	if (!cdata) {
-		dev_err(&pdev->dev, "Error: No device match data found\n");
-		return -ENODEV;
-	}
+	size = struct_size(tdma, channels, cdata->nr_channels);
 
-	tdma = devm_kzalloc(&pdev->dev,
-			    struct_size(tdma, channels, cdata->nr_channels),
-			    GFP_KERNEL);
+	tdma = devm_kzalloc(&pdev->dev, size, GFP_KERNEL);
 	if (!tdma)
 		return -ENOMEM;
 
@@ -1424,10 +1434,8 @@ static int tegra_dma_probe(struct platform_device *pdev)
 	else
 		ret = pm_runtime_get_sync(&pdev->dev);
 
-	if (ret < 0) {
-		pm_runtime_disable(&pdev->dev);
-		return ret;
-	}
+	if (ret < 0)
+		goto err_pm_disable;
 
 	/* Reset DMA controller */
 	reset_control_assert(tdma->rst);
@@ -1470,13 +1478,13 @@ static int tegra_dma_probe(struct platform_device *pdev)
 		tdc->dma_chan.device = &tdma->dma_dev;
 		dma_cookie_init(&tdc->dma_chan);
 		list_add_tail(&tdc->dma_chan.device_node,
-				&tdma->dma_dev.channels);
+			      &tdma->dma_dev.channels);
 		tdc->tdma = tdma;
 		tdc->id = i;
 		tdc->slave_id = TEGRA_APBDMA_SLAVE_ID_INVALID;
 
 		tasklet_init(&tdc->tasklet, tegra_dma_tasklet,
-				(unsigned long)tdc);
+			     (unsigned long)tdc);
 		spin_lock_init(&tdc->lock);
 
 		INIT_LIST_HEAD(&tdc->pending_sg_req);
@@ -1528,16 +1536,19 @@ static int tegra_dma_probe(struct platform_device *pdev)
 		goto err_unregister_dma_dev;
 	}
 
-	dev_info(&pdev->dev, "Tegra20 APB DMA driver register %d channels\n",
-			cdata->nr_channels);
+	dev_info(&pdev->dev, "Tegra20 APB DMA driver registered %d channels\n",
+		 cdata->nr_channels);
+
 	return 0;
 
 err_unregister_dma_dev:
 	dma_async_device_unregister(&tdma->dma_dev);
+
 err_pm_disable:
 	pm_runtime_disable(&pdev->dev);
 	if (!pm_runtime_status_suspended(&pdev->dev))
 		tegra_dma_runtime_suspend(&pdev->dev);
+
 	return ret;
 }
 
@@ -1557,7 +1568,7 @@ static int tegra_dma_remove(struct platform_device *pdev)
 static int tegra_dma_runtime_suspend(struct device *dev)
 {
 	struct tegra_dma *tdma = dev_get_drvdata(dev);
-	int i;
+	unsigned int i;
 
 	tdma->reg_gen = tdma_read(tdma, TEGRA_APBDMA_GENERAL);
 	for (i = 0; i < tdma->chip_data->nr_channels; i++) {
@@ -1586,7 +1597,8 @@ static int tegra_dma_runtime_suspend(struct device *dev)
 static int tegra_dma_runtime_resume(struct device *dev)
 {
 	struct tegra_dma *tdma = dev_get_drvdata(dev);
-	int i, ret;
+	unsigned int i;
+	int ret;
 
 	ret = clk_prepare_enable(tdma->dma_clk);
 	if (ret < 0) {
@@ -1614,7 +1626,7 @@ static int tegra_dma_runtime_resume(struct device *dev)
 		tdc_write(tdc, TEGRA_APBDMA_CHAN_AHBSEQ, ch_reg->ahb_seq);
 		tdc_write(tdc, TEGRA_APBDMA_CHAN_AHBPTR, ch_reg->ahb_ptr);
 		tdc_write(tdc, TEGRA_APBDMA_CHAN_CSR,
-			(ch_reg->csr & ~TEGRA_APBDMA_CSR_ENB));
+			  ch_reg->csr & ~TEGRA_APBDMA_CSR_ENB);
 	}
 
 	return 0;
-- 
2.24.0

[PATCH v3 09/13] dmaengine: tegra-apb: Remove runtime PM usage

[Dmitry Osipenko]

There is no benefit from runtime PM usage for the APB DMA driver because
it enables clock at the time of channel's allocation and thus clock stays
enabled all the time in practice, secondly there is benefit from manually
disabled clock because hardware auto-gates it during idle by itself.

Signed-off-by: Dmitry Osipenko <digetx@gmail.com>
---
 drivers/dma/tegra20-apb-dma.c | 76 +++++++++++------------------------
 1 file changed, 24 insertions(+), 52 deletions(-)

diff --git a/drivers/dma/tegra20-apb-dma.c b/drivers/dma/tegra20-apb-dma.c
index 804007cbd6f0..840a58e782ec 100644
--- a/drivers/dma/tegra20-apb-dma.c
+++ b/drivers/dma/tegra20-apb-dma.c
@@ -21,7 +21,6 @@
 #include <linux/of_dma.h>
 #include <linux/platform_device.h>
 #include <linux/pm.h>
-#include <linux/pm_runtime.h>
 #include <linux/reset.h>
 #include <linux/slab.h>
 
@@ -266,8 +265,6 @@ static inline struct device *tdc2dev(struct tegra_dma_channel *tdc)
 }
 
 static dma_cookie_t tegra_dma_tx_submit(struct dma_async_tx_descriptor *tx);
-static int tegra_dma_runtime_suspend(struct device *dev);
-static int tegra_dma_runtime_resume(struct device *dev);
 
 /* Get DMA desc from free list, if not there then allocate it.  */
 static struct tegra_dma_desc *tegra_dma_desc_get(struct tegra_dma_channel *tdc)
@@ -1280,22 +1277,15 @@ tegra_dma_prep_dma_cyclic(struct dma_chan *dc, dma_addr_t buf_addr,
 static int tegra_dma_alloc_chan_resources(struct dma_chan *dc)
 {
 	struct tegra_dma_channel *tdc = to_tegra_dma_chan(dc);
-	struct tegra_dma *tdma = tdc->tdma;
-	int ret;
 
 	dma_cookie_init(&tdc->dma_chan);
 
-	ret = pm_runtime_get_sync(tdma->dev);
-	if (ret < 0)
-		return ret;
-
 	return 0;
 }
 
 static void tegra_dma_free_chan_resources(struct dma_chan *dc)
 {
 	struct tegra_dma_channel *tdc = to_tegra_dma_chan(dc);
-	struct tegra_dma *tdma = tdc->tdma;
 	struct tegra_dma_desc *dma_desc;
 	struct tegra_dma_sg_req *sg_req;
 	struct list_head dma_desc_list;
@@ -1328,7 +1318,6 @@ static void tegra_dma_free_chan_resources(struct dma_chan *dc)
 		list_del(&sg_req->node);
 		kfree(sg_req);
 	}
-	pm_runtime_put(tdma->dev);
 
 	tdc->slave_id = TEGRA_APBDMA_SLAVE_ID_INVALID;
 }
@@ -1428,27 +1417,6 @@ static int tegra_dma_probe(struct platform_device *pdev)
 
 	spin_lock_init(&tdma->global_lock);
 
-	pm_runtime_enable(&pdev->dev);
-	if (!pm_runtime_enabled(&pdev->dev))
-		ret = tegra_dma_runtime_resume(&pdev->dev);
-	else
-		ret = pm_runtime_get_sync(&pdev->dev);
-
-	if (ret < 0)
-		goto err_pm_disable;
-
-	/* Reset DMA controller */
-	reset_control_assert(tdma->rst);
-	udelay(2);
-	reset_control_deassert(tdma->rst);
-
-	/* Enable global DMA registers */
-	tdma_write(tdma, TEGRA_APBDMA_GENERAL, TEGRA_APBDMA_GENERAL_ENABLE);
-	tdma_write(tdma, TEGRA_APBDMA_CONTROL, 0);
-	tdma_write(tdma, TEGRA_APBDMA_IRQ_MASK_SET, 0xFFFFFFFFul);
-
-	pm_runtime_put(&pdev->dev);
-
 	INIT_LIST_HEAD(&tdma->dma_dev.channels);
 	for (i = 0; i < cdata->nr_channels; i++) {
 		struct tegra_dma_channel *tdc = &tdma->channels[i];
@@ -1460,9 +1428,8 @@ static int tegra_dma_probe(struct platform_device *pdev)
 
 		irq = platform_get_irq(pdev, i);
 		if (irq < 0) {
-			ret = irq;
 			dev_err(&pdev->dev, "No irq resource for chan %d\n", i);
-			goto err_pm_disable;
+			return irq;
 		}
 
 		snprintf(tdc->name, sizeof(tdc->name), "apbdma.%d", i);
@@ -1472,7 +1439,7 @@ static int tegra_dma_probe(struct platform_device *pdev)
 			dev_err(&pdev->dev,
 				"request_irq failed with err %d channel %d\n",
 				ret, i);
-			goto err_pm_disable;
+			return ret;
 		}
 
 		tdc->dma_chan.device = &tdma->dma_dev;
@@ -1493,6 +1460,20 @@ static int tegra_dma_probe(struct platform_device *pdev)
 		INIT_LIST_HEAD(&tdc->cb_desc);
 	}
 
+	ret = clk_prepare_enable(tdma->dma_clk);
+	if (ret < 0) {
+		dev_err(&pdev->dev, "clk_enable failed: %d\n", ret);
+		return ret;
+	}
+
+	/* Reset DMA controller */
+	reset_control_reset(tdma->rst);
+
+	/* Enable global DMA registers */
+	tdma_write(tdma, TEGRA_APBDMA_GENERAL, TEGRA_APBDMA_GENERAL_ENABLE);
+	tdma_write(tdma, TEGRA_APBDMA_CONTROL, 0);
+	tdma_write(tdma, TEGRA_APBDMA_IRQ_MASK_SET, 0xFFFFFFFFul);
+
 	dma_cap_set(DMA_SLAVE, tdma->dma_dev.cap_mask);
 	dma_cap_set(DMA_PRIVATE, tdma->dma_dev.cap_mask);
 	dma_cap_set(DMA_CYCLIC, tdma->dma_dev.cap_mask);
@@ -1525,7 +1506,7 @@ static int tegra_dma_probe(struct platform_device *pdev)
 	if (ret < 0) {
 		dev_err(&pdev->dev,
 			"Tegra20 APB DMA driver registration failed %d\n", ret);
-		goto err_pm_disable;
+		goto err_clk_disable;
 	}
 
 	ret = of_dma_controller_register(pdev->dev.of_node,
@@ -1544,10 +1525,8 @@ static int tegra_dma_probe(struct platform_device *pdev)
 err_unregister_dma_dev:
 	dma_async_device_unregister(&tdma->dma_dev);
 
-err_pm_disable:
-	pm_runtime_disable(&pdev->dev);
-	if (!pm_runtime_status_suspended(&pdev->dev))
-		tegra_dma_runtime_suspend(&pdev->dev);
+err_clk_disable:
+	clk_disable_unprepare(tdma->dma_clk);
 
 	return ret;
 }
@@ -1557,15 +1536,12 @@ static int tegra_dma_remove(struct platform_device *pdev)
 	struct tegra_dma *tdma = platform_get_drvdata(pdev);
 
 	dma_async_device_unregister(&tdma->dma_dev);
-
-	pm_runtime_disable(&pdev->dev);
-	if (!pm_runtime_status_suspended(&pdev->dev))
-		tegra_dma_runtime_suspend(&pdev->dev);
+	clk_disable_unprepare(tdma->dma_clk);
 
 	return 0;
 }
 
-static int tegra_dma_runtime_suspend(struct device *dev)
+static int __maybe_unused tegra_dma_dev_suspend(struct device *dev)
 {
 	struct tegra_dma *tdma = dev_get_drvdata(dev);
 	unsigned int i;
@@ -1594,7 +1570,7 @@ static int tegra_dma_runtime_suspend(struct device *dev)
 	return 0;
 }
 
-static int tegra_dma_runtime_resume(struct device *dev)
+static int __maybe_unused tegra_dma_dev_resume(struct device *dev)
 {
 	struct tegra_dma *tdma = dev_get_drvdata(dev);
 	unsigned int i;
@@ -1632,12 +1608,8 @@ static int tegra_dma_runtime_resume(struct device *dev)
 	return 0;
 }
 
-static const struct dev_pm_ops tegra_dma_dev_pm_ops = {
-	SET_RUNTIME_PM_OPS(tegra_dma_runtime_suspend, tegra_dma_runtime_resume,
-			   NULL)
-	SET_SYSTEM_SLEEP_PM_OPS(pm_runtime_force_suspend,
-				pm_runtime_force_resume)
-};
+static SIMPLE_DEV_PM_OPS(tegra_dma_dev_pm_ops, tegra_dma_dev_suspend,
+			 tegra_dma_dev_resume);
 
 static const struct of_device_id tegra_dma_of_match[] = {
 	{
-- 
2.24.0

[PATCH v3 10/13] dmaengine: tegra-apb: Clean up suspend-resume

[Dmitry Osipenko]

It is enough to check whether hardware is busy on suspend and to reset
it across of suspend-resume because channel's configuration is fully
re-programmed on each DMA transaction anyways and because save-restore
of an active channel won't end up well without pausing transfer prior to
saving of the state (note that all channels shall be idling at the time of
suspend, so save-restore is not needed at all).

Signed-off-by: Dmitry Osipenko <digetx@gmail.com>
---
 drivers/dma/tegra20-apb-dma.c | 122 +++++++++++++++-------------------
 1 file changed, 55 insertions(+), 67 deletions(-)

diff --git a/drivers/dma/tegra20-apb-dma.c b/drivers/dma/tegra20-apb-dma.c
index 840a58e782ec..a75d2dd850c7 100644
--- a/drivers/dma/tegra20-apb-dma.c
+++ b/drivers/dma/tegra20-apb-dma.c
@@ -220,9 +220,6 @@ struct tegra_dma {
 	 */
 	u32				global_pause_count;
 
-	/* Some register need to be cache before suspend */
-	u32				reg_gen;
-
 	/* Last member of the structure */
 	struct tegra_dma_channel channels[0];
 };
@@ -1380,6 +1377,40 @@ static const struct tegra_dma_chip_data tegra148_dma_chip_data = {
 	.support_separate_wcount_reg = true,
 };
 
+static int tegra_dma_init_hw(struct tegra_dma *tdma)
+{
+	int err;
+
+	err = reset_control_assert(tdma->rst);
+	if (err) {
+		dev_err(tdma->dev, "failed to assert reset: %d\n", err);
+		return err;
+	}
+
+	err = clk_prepare_enable(tdma->dma_clk);
+	if (err) {
+		dev_err(tdma->dev, "failed to enable clk: %d\n", err);
+		return err;
+	}
+
+	/* Reset DMA controller */
+	udelay(2);
+	reset_control_deassert(tdma->rst);
+
+	/* Enable global DMA registers */
+	tdma_write(tdma, TEGRA_APBDMA_GENERAL, TEGRA_APBDMA_GENERAL_ENABLE);
+	tdma_write(tdma, TEGRA_APBDMA_CONTROL, 0);
+	tdma_write(tdma, TEGRA_APBDMA_IRQ_MASK_SET, 0xFFFFFFFF);
+
+	return 0;
+}
+
+static void tegra_dma_deinit_hw(struct tegra_dma *tdma)
+{
+	reset_control_reset(tdma->rst);
+	clk_disable_unprepare(tdma->dma_clk);
+}
+
 static int tegra_dma_probe(struct platform_device *pdev)
 {
 	const struct tegra_dma_chip_data *cdata;
@@ -1460,19 +1491,9 @@ static int tegra_dma_probe(struct platform_device *pdev)
 		INIT_LIST_HEAD(&tdc->cb_desc);
 	}
 
-	ret = clk_prepare_enable(tdma->dma_clk);
-	if (ret < 0) {
-		dev_err(&pdev->dev, "clk_enable failed: %d\n", ret);
+	ret = tegra_dma_init_hw(tdma);
+	if (ret)
 		return ret;
-	}
-
-	/* Reset DMA controller */
-	reset_control_reset(tdma->rst);
-
-	/* Enable global DMA registers */
-	tdma_write(tdma, TEGRA_APBDMA_GENERAL, TEGRA_APBDMA_GENERAL_ENABLE);
-	tdma_write(tdma, TEGRA_APBDMA_CONTROL, 0);
-	tdma_write(tdma, TEGRA_APBDMA_IRQ_MASK_SET, 0xFFFFFFFFul);
 
 	dma_cap_set(DMA_SLAVE, tdma->dma_dev.cap_mask);
 	dma_cap_set(DMA_PRIVATE, tdma->dma_dev.cap_mask);
@@ -1506,7 +1527,7 @@ static int tegra_dma_probe(struct platform_device *pdev)
 	if (ret < 0) {
 		dev_err(&pdev->dev,
 			"Tegra20 APB DMA driver registration failed %d\n", ret);
-		goto err_clk_disable;
+		goto err_deinit_hw;
 	}
 
 	ret = of_dma_controller_register(pdev->dev.of_node,
@@ -1525,8 +1546,8 @@ static int tegra_dma_probe(struct platform_device *pdev)
 err_unregister_dma_dev:
 	dma_async_device_unregister(&tdma->dma_dev);
 
-err_clk_disable:
-	clk_disable_unprepare(tdma->dma_clk);
+err_deinit_hw:
+	tegra_dma_deinit_hw(tdma);
 
 	return ret;
 }
@@ -1536,7 +1557,7 @@ static int tegra_dma_remove(struct platform_device *pdev)
 	struct tegra_dma *tdma = platform_get_drvdata(pdev);
 
 	dma_async_device_unregister(&tdma->dma_dev);
-	clk_disable_unprepare(tdma->dma_clk);
+	tegra_dma_deinit_hw(tdma);
 
 	return 0;
 }
@@ -1544,28 +1565,26 @@ static int tegra_dma_remove(struct platform_device *pdev)
 static int __maybe_unused tegra_dma_dev_suspend(struct device *dev)
 {
 	struct tegra_dma *tdma = dev_get_drvdata(dev);
+	unsigned long flags;
 	unsigned int i;
+	bool busy;
 
-	tdma->reg_gen = tdma_read(tdma, TEGRA_APBDMA_GENERAL);
 	for (i = 0; i < tdma->chip_data->nr_channels; i++) {
 		struct tegra_dma_channel *tdc = &tdma->channels[i];
-		struct tegra_dma_channel_regs *ch_reg = &tdc->channel_reg;
-
-		/* Only save the state of DMA channels that are in use */
-		if (!tdc->config_init)
-			continue;
-
-		ch_reg->csr = tdc_read(tdc, TEGRA_APBDMA_CHAN_CSR);
-		ch_reg->ahb_ptr = tdc_read(tdc, TEGRA_APBDMA_CHAN_AHBPTR);
-		ch_reg->apb_ptr = tdc_read(tdc, TEGRA_APBDMA_CHAN_APBPTR);
-		ch_reg->ahb_seq = tdc_read(tdc, TEGRA_APBDMA_CHAN_AHBSEQ);
-		ch_reg->apb_seq = tdc_read(tdc, TEGRA_APBDMA_CHAN_APBSEQ);
-		if (tdma->chip_data->support_separate_wcount_reg)
-			ch_reg->wcount = tdc_read(tdc,
-						  TEGRA_APBDMA_CHAN_WCOUNT);
+
+		spin_lock_irqsave(&tdc->lock, flags);
+		busy = tdc->busy;
+		spin_unlock_irqrestore(&tdc->lock, flags);
+
+		if (busy) {
+			dev_err(tdma->dev, "channel %u busy\n", i);
+			return -EBUSY;
+		}
+
+		tasklet_kill(&tdc->tasklet);
 	}
 
-	clk_disable_unprepare(tdma->dma_clk);
+	tegra_dma_deinit_hw(tdma);
 
 	return 0;
 }
@@ -1573,39 +1592,8 @@ static int __maybe_unused tegra_dma_dev_suspend(struct device *dev)
 static int __maybe_unused tegra_dma_dev_resume(struct device *dev)
 {
 	struct tegra_dma *tdma = dev_get_drvdata(dev);
-	unsigned int i;
-	int ret;
 
-	ret = clk_prepare_enable(tdma->dma_clk);
-	if (ret < 0) {
-		dev_err(dev, "clk_enable failed: %d\n", ret);
-		return ret;
-	}
-
-	tdma_write(tdma, TEGRA_APBDMA_GENERAL, tdma->reg_gen);
-	tdma_write(tdma, TEGRA_APBDMA_CONTROL, 0);
-	tdma_write(tdma, TEGRA_APBDMA_IRQ_MASK_SET, 0xFFFFFFFFul);
-
-	for (i = 0; i < tdma->chip_data->nr_channels; i++) {
-		struct tegra_dma_channel *tdc = &tdma->channels[i];
-		struct tegra_dma_channel_regs *ch_reg = &tdc->channel_reg;
-
-		/* Only restore the state of DMA channels that are in use */
-		if (!tdc->config_init)
-			continue;
-
-		if (tdma->chip_data->support_separate_wcount_reg)
-			tdc_write(tdc, TEGRA_APBDMA_CHAN_WCOUNT,
-				  ch_reg->wcount);
-		tdc_write(tdc, TEGRA_APBDMA_CHAN_APBSEQ, ch_reg->apb_seq);
-		tdc_write(tdc, TEGRA_APBDMA_CHAN_APBPTR, ch_reg->apb_ptr);
-		tdc_write(tdc, TEGRA_APBDMA_CHAN_AHBSEQ, ch_reg->ahb_seq);
-		tdc_write(tdc, TEGRA_APBDMA_CHAN_AHBPTR, ch_reg->ahb_ptr);
-		tdc_write(tdc, TEGRA_APBDMA_CHAN_CSR,
-			  ch_reg->csr & ~TEGRA_APBDMA_CSR_ENB);
-	}
-
-	return 0;
+	return tegra_dma_init_hw(tdma);
 }
 
 static SIMPLE_DEV_PM_OPS(tegra_dma_dev_pm_ops, tegra_dma_dev_suspend,
-- 
2.24.0

[PATCH v3 11/13] dmaengine: tegra-apb: Add missing of_dma_controller_free

[Dmitry Osipenko]

The DMA controller shall be released on driver's removal.

Signed-off-by: Dmitry Osipenko <digetx@gmail.com>
---
 drivers/dma/tegra20-apb-dma.c | 1 +
 1 file changed, 1 insertion(+)

diff --git a/drivers/dma/tegra20-apb-dma.c b/drivers/dma/tegra20-apb-dma.c
index a75d2dd850c7..108307c428d1 100644
--- a/drivers/dma/tegra20-apb-dma.c
+++ b/drivers/dma/tegra20-apb-dma.c
@@ -1556,6 +1556,7 @@ static int tegra_dma_remove(struct platform_device *pdev)
 {
 	struct tegra_dma *tdma = platform_get_drvdata(pdev);
 
+	of_dma_controller_free(pdev->dev.of_node);
 	dma_async_device_unregister(&tdma->dma_dev);
 	tegra_dma_deinit_hw(tdma);
 
-- 
2.24.0

[PATCH v3 12/13] dmaengine: tegra-apb: Allow to compile as a loadable kernel module

[Dmitry Osipenko]

The driver's removal was fixed by a recent commit and module load/unload
is working well now, tested on Tegra30.

Signed-off-by: Dmitry Osipenko <digetx@gmail.com>
---
 drivers/dma/Kconfig | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/dma/Kconfig b/drivers/dma/Kconfig
index 6fa1eba9d477..9f43e2cae8b4 100644
--- a/drivers/dma/Kconfig
+++ b/drivers/dma/Kconfig
@@ -586,7 +586,7 @@ config TXX9_DMAC
 	  integrated in chips such as the Toshiba TX4927/38/39.
 
 config TEGRA20_APB_DMA
-	bool "NVIDIA Tegra20 APB DMA support"
+	tristate "NVIDIA Tegra20 APB DMA support"
 	depends on ARCH_TEGRA
 	select DMA_ENGINE
 	help
-- 
2.24.0

[PATCH v3 13/13] dmaengine: tegra-apb: Remove MODULE_ALIAS

[Dmitry Osipenko]

Tegra APB DMA driver is an Open Firmware driver and thus it uses OF alias
naming scheme which overrides MODULE_ALIAS, meaning that MODULE_ALIAS does
nothing and could be removed safely.

Signed-off-by: Dmitry Osipenko <digetx@gmail.com>
---
 drivers/dma/tegra20-apb-dma.c | 1 -
 1 file changed, 1 deletion(-)

diff --git a/drivers/dma/tegra20-apb-dma.c b/drivers/dma/tegra20-apb-dma.c
index 108307c428d1..7a6a7cb81e8a 100644
--- a/drivers/dma/tegra20-apb-dma.c
+++ b/drivers/dma/tegra20-apb-dma.c
@@ -1630,7 +1630,6 @@ static struct platform_driver tegra_dmac_driver = {
 
 module_platform_driver(tegra_dmac_driver);
 
-MODULE_ALIAS("platform:tegra20-apbdma");
 MODULE_DESCRIPTION("NVIDIA Tegra APB DMA Controller driver");
 MODULE_AUTHOR("Laxman Dewangan <ldewangan@nvidia.com>");
 MODULE_LICENSE("GPL v2");
-- 
2.24.0

Re: [PATCH v3 09/13] dmaengine: tegra-apb: Remove runtime PM usage

[Jon Hunter]

On 06/01/2020 01:17, Dmitry Osipenko wrote:
> There is no benefit from runtime PM usage for the APB DMA driver because
> it enables clock at the time of channel's allocation and thus clock stays
> enabled all the time in practice, secondly there is benefit from manually
> disabled clock because hardware auto-gates it during idle by itself.

This assumes that the channel is allocated during a driver
initialisation. That may not always be the case. I believe audio is one
case where channels are requested at the start of audio playback.

Jon

-- 
nvpublic

Re: [PATCH v3 09/13] dmaengine: tegra-apb: Remove runtime PM usage

[Jon Hunter]

On 06/01/2020 01:17, Dmitry Osipenko wrote:
> There is no benefit from runtime PM usage for the APB DMA driver because
> it enables clock at the time of channel's allocation and thus clock stays
> enabled all the time in practice, secondly there is benefit from manually
> disabled clock because hardware auto-gates it during idle by itself.

This assumes that the channel is allocated during a driver
initialisation. That may not always be the case. I believe audio is one
case where channels are requested at the start of audio playback.

Jon

-- 
nvpublic

Re: [PATCH v3 09/13] dmaengine: tegra-apb: Remove runtime PM usage

[Dmitry Osipenko]

Hello Jon,

07.01.2020 18:13, Jon Hunter пишет:
> 
> On 06/01/2020 01:17, Dmitry Osipenko wrote:
>> There is no benefit from runtime PM usage for the APB DMA driver because
>> it enables clock at the time of channel's allocation and thus clock stays
>> enabled all the time in practice, secondly there is benefit from manually
>> disabled clock because hardware auto-gates it during idle by itself.
> 
> This assumes that the channel is allocated during a driver
> initialisation. That may not always be the case. I believe audio is one
> case where channels are requested at the start of audio playback.

At least serial, I2C, SPI and T20 FUSE are permanently keeping channels
allocated, thus audio is an exception here. I don't think that it's
practical to assume that there is a real-world use-case where audio
driver is the only active DMA client.

The benefits of gating the DMA clock are also dim, do you have any
power-consumption numbers that show that it's really worth to care about
the clock-gating?

Re: [PATCH v3 09/13] dmaengine: tegra-apb: Remove runtime PM usage

[Jon Hunter]

On 07/01/2020 17:12, Dmitry Osipenko wrote:
> 07.01.2020 18:13, Jon Hunter пишет:
>>
>> On 06/01/2020 01:17, Dmitry Osipenko wrote:
>>> There is no benefit from runtime PM usage for the APB DMA driver because
>>> it enables clock at the time of channel's allocation and thus clock stays
>>> enabled all the time in practice, secondly there is benefit from manually
>>> disabled clock because hardware auto-gates it during idle by itself.
>>
>> This assumes that the channel is allocated during a driver
>> initialisation. That may not always be the case. I believe audio is one
>> case where channels are requested at the start of audio playback.
> 
> At least serial, I2C, SPI and T20 FUSE are permanently keeping channels
> allocated, thus audio is an exception here. I don't think that it's
> practical to assume that there is a real-world use-case where audio
> driver is the only active DMA client.
> 
> The benefits of gating the DMA clock are also dim, do you have any
> power-consumption numbers that show that it's really worth to care about
> the clock-gating?

No, but at the same time, I really don't see the point in this. In fact,
I think it is a step backwards. If we wanted to only enable clocks while
DMA channels are active we could. So I request you drop this.

Jon

-- 
nvpublic

Re: [PATCH v3 09/13] dmaengine: tegra-apb: Remove runtime PM usage

[Jon Hunter]

On 07/01/2020 17:12, Dmitry Osipenko wrote:
> 07.01.2020 18:13, Jon Hunter пишет:
>>
>> On 06/01/2020 01:17, Dmitry Osipenko wrote:
>>> There is no benefit from runtime PM usage for the APB DMA driver because
>>> it enables clock at the time of channel's allocation and thus clock stays
>>> enabled all the time in practice, secondly there is benefit from manually
>>> disabled clock because hardware auto-gates it during idle by itself.
>>
>> This assumes that the channel is allocated during a driver
>> initialisation. That may not always be the case. I believe audio is one
>> case where channels are requested at the start of audio playback.
> 
> At least serial, I2C, SPI and T20 FUSE are permanently keeping channels
> allocated, thus audio is an exception here. I don't think that it's
> practical to assume that there is a real-world use-case where audio
> driver is the only active DMA client.
> 
> The benefits of gating the DMA clock are also dim, do you have any
> power-consumption numbers that show that it's really worth to care about
> the clock-gating?

No, but at the same time, I really don't see the point in this. In fact,
I think it is a step backwards. If we wanted to only enable clocks while
DMA channels are active we could. So I request you drop this.

Jon

-- 
nvpublic

Re: [PATCH v3 00/13] NVIDIA Tegra APB DMA driver fixes and improvements

[Thierry Reding]

On Mon, 06 Jan 2020 04:16:55 +0300, Dmitry Osipenko wrote:
> Hello,
> 
> This is series fixes some problems that I spotted recently, secondly the
> driver's code gets a cleanup. Please review and apply, thanks in advance!
> 
> Changelog:
> 
> v3: - In the review comment to v1 Michał Mirosław suggested that "Prevent
>       race conditions on channel's freeing" does changes that deserve to
>       be separated into two patches. I factored out and improved tasklet
>       releasing into this new patch:
> 
>         dmaengine: tegra-apb: Clean up tasklet releasing
> 
>     - The "Fix use-after-free" patch got an improved commit message.
> 
> v2: - I took another look at the driver and spotted few more things that
>       could be improved, which resulted in these new patches:
> 
>         dmaengine: tegra-apb: Remove runtime PM usage
>         dmaengine: tegra-apb: Clean up suspend-resume
>         dmaengine: tegra-apb: Add missing of_dma_controller_free
>         dmaengine: tegra-apb: Allow to compile as a loadable kernel module
>         dmaengine: tegra-apb: Remove MODULE_ALIAS
> 
> Dmitry Osipenko (13):
>   dmaengine: tegra-apb: Fix use-after-free
>   dmaengine: tegra-apb: Implement synchronization callback
>   dmaengine: tegra-apb: Prevent race conditions on channel's freeing
>   dmaengine: tegra-apb: Clean up tasklet releasing
>   dmaengine: tegra-apb: Prevent race conditions of tasklet vs free list
>   dmaengine: tegra-apb: Use devm_platform_ioremap_resource
>   dmaengine: tegra-apb: Use devm_request_irq
>   dmaengine: tegra-apb: Fix coding style problems
>   dmaengine: tegra-apb: Remove runtime PM usage
>   dmaengine: tegra-apb: Clean up suspend-resume
>   dmaengine: tegra-apb: Add missing of_dma_controller_free
>   dmaengine: tegra-apb: Allow to compile as a loadable kernel module
>   dmaengine: tegra-apb: Remove MODULE_ALIAS
> 
>  drivers/dma/Kconfig           |   2 +-
>  drivers/dma/tegra20-apb-dma.c | 481 ++++++++++++++++------------------
>  2 files changed, 220 insertions(+), 263 deletions(-)

Test results:
  13 builds: 13 pass, 0 fail
  12 boots:  11 pass, 1 fail
  38 tests:  38 pass, 0 fail

Linux version: 5.5.0-rc5-gf9d40c056c0f
Boards tested: tegra20-ventana, tegra30-cardhu-a04, tegra124-jetson-tk1,
               tegra186-p2771-0000, tegra194-p2972-0000,
               tegra210-p2371-2180

Re: [PATCH v3 00/13] NVIDIA Tegra APB DMA driver fixes and improvements

[Dmitry Osipenko]

08.01.2020 15:51, Thierry Reding пишет:
> On Mon, 06 Jan 2020 04:16:55 +0300, Dmitry Osipenko wrote:
>> Hello,
>>
>> This is series fixes some problems that I spotted recently, secondly the
>> driver's code gets a cleanup. Please review and apply, thanks in advance!
>>
>> Changelog:
>>
>> v3: - In the review comment to v1 Michał Mirosław suggested that "Prevent
>>       race conditions on channel's freeing" does changes that deserve to
>>       be separated into two patches. I factored out and improved tasklet
>>       releasing into this new patch:
>>
>>         dmaengine: tegra-apb: Clean up tasklet releasing
>>
>>     - The "Fix use-after-free" patch got an improved commit message.
>>
>> v2: - I took another look at the driver and spotted few more things that
>>       could be improved, which resulted in these new patches:
>>
>>         dmaengine: tegra-apb: Remove runtime PM usage
>>         dmaengine: tegra-apb: Clean up suspend-resume
>>         dmaengine: tegra-apb: Add missing of_dma_controller_free
>>         dmaengine: tegra-apb: Allow to compile as a loadable kernel module
>>         dmaengine: tegra-apb: Remove MODULE_ALIAS
>>
>> Dmitry Osipenko (13):
>>   dmaengine: tegra-apb: Fix use-after-free
>>   dmaengine: tegra-apb: Implement synchronization callback
>>   dmaengine: tegra-apb: Prevent race conditions on channel's freeing
>>   dmaengine: tegra-apb: Clean up tasklet releasing
>>   dmaengine: tegra-apb: Prevent race conditions of tasklet vs free list
>>   dmaengine: tegra-apb: Use devm_platform_ioremap_resource
>>   dmaengine: tegra-apb: Use devm_request_irq
>>   dmaengine: tegra-apb: Fix coding style problems
>>   dmaengine: tegra-apb: Remove runtime PM usage
>>   dmaengine: tegra-apb: Clean up suspend-resume
>>   dmaengine: tegra-apb: Add missing of_dma_controller_free
>>   dmaengine: tegra-apb: Allow to compile as a loadable kernel module
>>   dmaengine: tegra-apb: Remove MODULE_ALIAS
>>
>>  drivers/dma/Kconfig           |   2 +-
>>  drivers/dma/tegra20-apb-dma.c | 481 ++++++++++++++++------------------
>>  2 files changed, 220 insertions(+), 263 deletions(-)
> 
> Test results:
>   13 builds: 13 pass, 0 fail
>   12 boots:  11 pass, 1 fail

I'm not sure how to interpret this result. Could you please explain what
that fail means?

>   38 tests:  38 pass, 0 fail
> 
> Linux version: 5.5.0-rc5-gf9d40c056c0f
> Boards tested: tegra20-ventana, tegra30-cardhu-a04, tegra124-jetson-tk1,
>                tegra186-p2771-0000, tegra194-p2972-0000,
>                tegra210-p2371-2180
> 

Will be awesome to see the detailed testing results, at least console
log like it was with NVTB.

Re: [PATCH v3 09/13] dmaengine: tegra-apb: Remove runtime PM usage

[Dmitry Osipenko]

07.01.2020 21:38, Jon Hunter пишет:
> 
> On 07/01/2020 17:12, Dmitry Osipenko wrote:
>> 07.01.2020 18:13, Jon Hunter пишет:
>>>
>>> On 06/01/2020 01:17, Dmitry Osipenko wrote:
>>>> There is no benefit from runtime PM usage for the APB DMA driver because
>>>> it enables clock at the time of channel's allocation and thus clock stays
>>>> enabled all the time in practice, secondly there is benefit from manually
>>>> disabled clock because hardware auto-gates it during idle by itself.
>>>
>>> This assumes that the channel is allocated during a driver
>>> initialisation. That may not always be the case. I believe audio is one
>>> case where channels are requested at the start of audio playback.
>>
>> At least serial, I2C, SPI and T20 FUSE are permanently keeping channels
>> allocated, thus audio is an exception here. I don't think that it's
>> practical to assume that there is a real-world use-case where audio
>> driver is the only active DMA client.
>>
>> The benefits of gating the DMA clock are also dim, do you have any
>> power-consumption numbers that show that it's really worth to care about
>> the clock-gating?
> 
> No, but at the same time, I really don't see the point in this. In fact,
> I think it is a step backwards. If we wanted to only enable clocks while
> DMA channels are active we could. So I request you drop this.

I'll take a look at making RPM active only during the time of DMA
activity, otherwise it's pretty much a dead code as it is now.

Re: [PATCH v3 00/13] NVIDIA Tegra APB DMA driver fixes and improvements

[Thierry Reding]

[-- Attachment #1: Type: text/plain, Size: 5074 bytes --]

On Wed, Jan 08, 2020 at 06:07:46PM +0300, Dmitry Osipenko wrote:
> 08.01.2020 15:51, Thierry Reding пишет:
> > On Mon, 06 Jan 2020 04:16:55 +0300, Dmitry Osipenko wrote:
> >> Hello,
> >>
> >> This is series fixes some problems that I spotted recently, secondly the
> >> driver's code gets a cleanup. Please review and apply, thanks in advance!
> >>
> >> Changelog:
> >>
> >> v3: - In the review comment to v1 Michał Mirosław suggested that "Prevent
> >>       race conditions on channel's freeing" does changes that deserve to
> >>       be separated into two patches. I factored out and improved tasklet
> >>       releasing into this new patch:
> >>
> >>         dmaengine: tegra-apb: Clean up tasklet releasing
> >>
> >>     - The "Fix use-after-free" patch got an improved commit message.
> >>
> >> v2: - I took another look at the driver and spotted few more things that
> >>       could be improved, which resulted in these new patches:
> >>
> >>         dmaengine: tegra-apb: Remove runtime PM usage
> >>         dmaengine: tegra-apb: Clean up suspend-resume
> >>         dmaengine: tegra-apb: Add missing of_dma_controller_free
> >>         dmaengine: tegra-apb: Allow to compile as a loadable kernel module
> >>         dmaengine: tegra-apb: Remove MODULE_ALIAS
> >>
> >> Dmitry Osipenko (13):
> >>   dmaengine: tegra-apb: Fix use-after-free
> >>   dmaengine: tegra-apb: Implement synchronization callback
> >>   dmaengine: tegra-apb: Prevent race conditions on channel's freeing
> >>   dmaengine: tegra-apb: Clean up tasklet releasing
> >>   dmaengine: tegra-apb: Prevent race conditions of tasklet vs free list
> >>   dmaengine: tegra-apb: Use devm_platform_ioremap_resource
> >>   dmaengine: tegra-apb: Use devm_request_irq
> >>   dmaengine: tegra-apb: Fix coding style problems
> >>   dmaengine: tegra-apb: Remove runtime PM usage
> >>   dmaengine: tegra-apb: Clean up suspend-resume
> >>   dmaengine: tegra-apb: Add missing of_dma_controller_free
> >>   dmaengine: tegra-apb: Allow to compile as a loadable kernel module
> >>   dmaengine: tegra-apb: Remove MODULE_ALIAS
> >>
> >>  drivers/dma/Kconfig           |   2 +-
> >>  drivers/dma/tegra20-apb-dma.c | 481 ++++++++++++++++------------------
> >>  2 files changed, 220 insertions(+), 263 deletions(-)
> > 
> > Test results:
> >   13 builds: 13 pass, 0 fail
> >   12 boots:  11 pass, 1 fail
> 
> I'm not sure how to interpret this result. Could you please explain what
> that fail means?

Yeah, Jon and I have been discussing about whether to expose this as
failure or not. Basically what I'm trying to do here is to provide
automated test results. The way that I'm currently doing this is to run
these patches through our internal test farm and if the tests succeed,
send out the results and reply with a Tested-by: to all patches so that
patchwork has a record of it.

So just the fact that the test results were sent means the tests passed.
I do see now that that's not at all clear, so I'm going to have to tweak
the summary a bit to clarify that.

I've also added something like this to the bottom of the summary:

	Warnings:
	- 1 failure for board tegra186-p2771-0000 but tests passed

This is supposed to indicate that the one failure that you're seeing in
the test results is an intermittent failure. Looking at the logs I see
that at some point there was an intermittent boot failure for Jetson TX2
but then the test farm rebooted the system and then it succeeded and ran
the tests successfully.

So I guess in general this means that if you get that test summary and a
list of Tested-by: replies to the patches, all is well. Unfortunately I
don't really have a useful way of reporting failure, so I'm not sending
out a summary in that case. That means you currently can't distinguish
between whether the series hasn't been tested at all or whether it
failed. Although, I have also started to use patchwork checks to track
this in patchwork, so you could look at the patches in patchwork and see
if they have been tested, and that does record success or failure.

> >   38 tests:  38 pass, 0 fail
> > 
> > Linux version: 5.5.0-rc5-gf9d40c056c0f
> > Boards tested: tegra20-ventana, tegra30-cardhu-a04, tegra124-jetson-tk1,
> >                tegra186-p2771-0000, tegra194-p2972-0000,
> >                tegra210-p2371-2180
> > 
> 
> Will be awesome to see the detailed testing results, at least console
> log like it was with NVTB.

Yeah, I'm working on that. It's the only reason I'm not sending out
failure reports because it would just say that things failed without
giving you any indication about why.

Currently the plan is to upload more detailed test results to a public
location (perhaps github, like nvtb used to) and provide a link to them
in patchwork and the test summary.

Do you think that would be helpful? Anything else you think would be
useful to have in these reports? Or anything about the above that you
think is impractical for you as a contributor?

Thierry

[-- Attachment #2: signature.asc --]
[-- Type: application/pgp-signature, Size: 833 bytes --]

Re: [PATCH v3 00/13] NVIDIA Tegra APB DMA driver fixes and improvements

[Thierry Reding]

[-- Attachment #1: Type: text/plain, Size: 5074 bytes --]

On Wed, Jan 08, 2020 at 06:07:46PM +0300, Dmitry Osipenko wrote:
> 08.01.2020 15:51, Thierry Reding пишет:
> > On Mon, 06 Jan 2020 04:16:55 +0300, Dmitry Osipenko wrote:
> >> Hello,
> >>
> >> This is series fixes some problems that I spotted recently, secondly the
> >> driver's code gets a cleanup. Please review and apply, thanks in advance!
> >>
> >> Changelog:
> >>
> >> v3: - In the review comment to v1 Michał Mirosław suggested that "Prevent
> >>       race conditions on channel's freeing" does changes that deserve to
> >>       be separated into two patches. I factored out and improved tasklet
> >>       releasing into this new patch:
> >>
> >>         dmaengine: tegra-apb: Clean up tasklet releasing
> >>
> >>     - The "Fix use-after-free" patch got an improved commit message.
> >>
> >> v2: - I took another look at the driver and spotted few more things that
> >>       could be improved, which resulted in these new patches:
> >>
> >>         dmaengine: tegra-apb: Remove runtime PM usage
> >>         dmaengine: tegra-apb: Clean up suspend-resume
> >>         dmaengine: tegra-apb: Add missing of_dma_controller_free
> >>         dmaengine: tegra-apb: Allow to compile as a loadable kernel module
> >>         dmaengine: tegra-apb: Remove MODULE_ALIAS
> >>
> >> Dmitry Osipenko (13):
> >>   dmaengine: tegra-apb: Fix use-after-free
> >>   dmaengine: tegra-apb: Implement synchronization callback
> >>   dmaengine: tegra-apb: Prevent race conditions on channel's freeing
> >>   dmaengine: tegra-apb: Clean up tasklet releasing
> >>   dmaengine: tegra-apb: Prevent race conditions of tasklet vs free list
> >>   dmaengine: tegra-apb: Use devm_platform_ioremap_resource
> >>   dmaengine: tegra-apb: Use devm_request_irq
> >>   dmaengine: tegra-apb: Fix coding style problems
> >>   dmaengine: tegra-apb: Remove runtime PM usage
> >>   dmaengine: tegra-apb: Clean up suspend-resume
> >>   dmaengine: tegra-apb: Add missing of_dma_controller_free
> >>   dmaengine: tegra-apb: Allow to compile as a loadable kernel module
> >>   dmaengine: tegra-apb: Remove MODULE_ALIAS
> >>
> >>  drivers/dma/Kconfig           |   2 +-
> >>  drivers/dma/tegra20-apb-dma.c | 481 ++++++++++++++++------------------
> >>  2 files changed, 220 insertions(+), 263 deletions(-)
> > 
> > Test results:
> >   13 builds: 13 pass, 0 fail
> >   12 boots:  11 pass, 1 fail
> 
> I'm not sure how to interpret this result. Could you please explain what
> that fail means?

Yeah, Jon and I have been discussing about whether to expose this as
failure or not. Basically what I'm trying to do here is to provide
automated test results. The way that I'm currently doing this is to run
these patches through our internal test farm and if the tests succeed,
send out the results and reply with a Tested-by: to all patches so that
patchwork has a record of it.

So just the fact that the test results were sent means the tests passed.
I do see now that that's not at all clear, so I'm going to have to tweak
the summary a bit to clarify that.

I've also added something like this to the bottom of the summary:

	Warnings:
	- 1 failure for board tegra186-p2771-0000 but tests passed

This is supposed to indicate that the one failure that you're seeing in
the test results is an intermittent failure. Looking at the logs I see
that at some point there was an intermittent boot failure for Jetson TX2
but then the test farm rebooted the system and then it succeeded and ran
the tests successfully.

So I guess in general this means that if you get that test summary and a
list of Tested-by: replies to the patches, all is well. Unfortunately I
don't really have a useful way of reporting failure, so I'm not sending
out a summary in that case. That means you currently can't distinguish
between whether the series hasn't been tested at all or whether it
failed. Although, I have also started to use patchwork checks to track
this in patchwork, so you could look at the patches in patchwork and see
if they have been tested, and that does record success or failure.

> >   38 tests:  38 pass, 0 fail
> > 
> > Linux version: 5.5.0-rc5-gf9d40c056c0f
> > Boards tested: tegra20-ventana, tegra30-cardhu-a04, tegra124-jetson-tk1,
> >                tegra186-p2771-0000, tegra194-p2972-0000,
> >                tegra210-p2371-2180
> > 
> 
> Will be awesome to see the detailed testing results, at least console
> log like it was with NVTB.

Yeah, I'm working on that. It's the only reason I'm not sending out
failure reports because it would just say that things failed without
giving you any indication about why.

Currently the plan is to upload more detailed test results to a public
location (perhaps github, like nvtb used to) and provide a link to them
in patchwork and the test summary.

Do you think that would be helpful? Anything else you think would be
useful to have in these reports? Or anything about the above that you
think is impractical for you as a contributor?

Thierry

[-- Attachment #2: signature.asc --]
[-- Type: application/pgp-signature, Size: 833 bytes --]

Re: [PATCH v3 00/13] NVIDIA Tegra APB DMA driver fixes and improvements

[Dmitry Osipenko]

09.01.2020 13:04, Thierry Reding пишет:
> On Wed, Jan 08, 2020 at 06:07:46PM +0300, Dmitry Osipenko wrote:
>> 08.01.2020 15:51, Thierry Reding пишет:
>>> On Mon, 06 Jan 2020 04:16:55 +0300, Dmitry Osipenko wrote:
>>>> Hello,
>>>>
>>>> This is series fixes some problems that I spotted recently, secondly the
>>>> driver's code gets a cleanup. Please review and apply, thanks in advance!
>>>>
>>>> Changelog:
>>>>
>>>> v3: - In the review comment to v1 Michał Mirosław suggested that "Prevent
>>>>       race conditions on channel's freeing" does changes that deserve to
>>>>       be separated into two patches. I factored out and improved tasklet
>>>>       releasing into this new patch:
>>>>
>>>>         dmaengine: tegra-apb: Clean up tasklet releasing
>>>>
>>>>     - The "Fix use-after-free" patch got an improved commit message.
>>>>
>>>> v2: - I took another look at the driver and spotted few more things that
>>>>       could be improved, which resulted in these new patches:
>>>>
>>>>         dmaengine: tegra-apb: Remove runtime PM usage
>>>>         dmaengine: tegra-apb: Clean up suspend-resume
>>>>         dmaengine: tegra-apb: Add missing of_dma_controller_free
>>>>         dmaengine: tegra-apb: Allow to compile as a loadable kernel module
>>>>         dmaengine: tegra-apb: Remove MODULE_ALIAS
>>>>
>>>> Dmitry Osipenko (13):
>>>>   dmaengine: tegra-apb: Fix use-after-free
>>>>   dmaengine: tegra-apb: Implement synchronization callback
>>>>   dmaengine: tegra-apb: Prevent race conditions on channel's freeing
>>>>   dmaengine: tegra-apb: Clean up tasklet releasing
>>>>   dmaengine: tegra-apb: Prevent race conditions of tasklet vs free list
>>>>   dmaengine: tegra-apb: Use devm_platform_ioremap_resource
>>>>   dmaengine: tegra-apb: Use devm_request_irq
>>>>   dmaengine: tegra-apb: Fix coding style problems
>>>>   dmaengine: tegra-apb: Remove runtime PM usage
>>>>   dmaengine: tegra-apb: Clean up suspend-resume
>>>>   dmaengine: tegra-apb: Add missing of_dma_controller_free
>>>>   dmaengine: tegra-apb: Allow to compile as a loadable kernel module
>>>>   dmaengine: tegra-apb: Remove MODULE_ALIAS
>>>>
>>>>  drivers/dma/Kconfig           |   2 +-
>>>>  drivers/dma/tegra20-apb-dma.c | 481 ++++++++++++++++------------------
>>>>  2 files changed, 220 insertions(+), 263 deletions(-)
>>>
>>> Test results:
>>>   13 builds: 13 pass, 0 fail
>>>   12 boots:  11 pass, 1 fail
>>
>> I'm not sure how to interpret this result. Could you please explain what
>> that fail means?
> 
> Yeah, Jon and I have been discussing about whether to expose this as
> failure or not. Basically what I'm trying to do here is to provide
> automated test results. The way that I'm currently doing this is to run
> these patches through our internal test farm and if the tests succeed,
> send out the results and reply with a Tested-by: to all patches so that
> patchwork has a record of it.
> 
> So just the fact that the test results were sent means the tests passed.
> I do see now that that's not at all clear, so I'm going to have to tweak
> the summary a bit to clarify that.
> 
> I've also added something like this to the bottom of the summary:
> 
> 	Warnings:
> 	- 1 failure for board tegra186-p2771-0000 but tests passed
> 
> This is supposed to indicate that the one failure that you're seeing in
> the test results is an intermittent failure. Looking at the logs I see
> that at some point there was an intermittent boot failure for Jetson TX2
> but then the test farm rebooted the system and then it succeeded and ran
> the tests successfully.
> 
> So I guess in general this means that if you get that test summary and a
> list of Tested-by: replies to the patches, all is well. Unfortunately I
> don't really have a useful way of reporting failure, so I'm not sending
> out a summary in that case. That means you currently can't distinguish
> between whether the series hasn't been tested at all or whether it
> failed. Although, I have also started to use patchwork checks to track
> this in patchwork, so you could look at the patches in patchwork and see
> if they have been tested, and that does record success or failure.

The patchwork now says that all patches in this series failed.

Perhaps something needs to be done about filtering out the unimportant
intermittent noise.

>>>   38 tests:  38 pass, 0 fail
>>>
>>> Linux version: 5.5.0-rc5-gf9d40c056c0f
>>> Boards tested: tegra20-ventana, tegra30-cardhu-a04, tegra124-jetson-tk1,
>>>                tegra186-p2771-0000, tegra194-p2972-0000,
>>>                tegra210-p2371-2180
>>>
>>
>> Will be awesome to see the detailed testing results, at least console
>> log like it was with NVTB.
> 
> Yeah, I'm working on that. It's the only reason I'm not sending out
> failure reports because it would just say that things failed without
> giving you any indication about why.
> 
> Currently the plan is to upload more detailed test results to a public
> location (perhaps github, like nvtb used to) and provide a link to them
> in patchwork and the test summary.
> 
> Do you think that would be helpful?

Yes, the full log is absolutely necessary in a case of problem.

> Anything else you think would be useful to have in these reports?

Optionally, there should be instructions about how to reproduce problem,
which includes rootfs, toolchain and etc.

> Or anything about the above that you think is impractical for you as a contributor?

The intermittent noise should be impractical to report in the short
logs, telling that tests failed. But probably it won't hurt to have a
warning, like you suggested above, and then also to have everything
reported in the detailed log.

Re: [PATCH v3 00/13] NVIDIA Tegra APB DMA driver fixes and improvements

[Dmitry Osipenko]

09.01.2020 13:04, Thierry Reding пишет:
> On Wed, Jan 08, 2020 at 06:07:46PM +0300, Dmitry Osipenko wrote:
>> 08.01.2020 15:51, Thierry Reding пишет:
>>> On Mon, 06 Jan 2020 04:16:55 +0300, Dmitry Osipenko wrote:
>>>> Hello,
>>>>
>>>> This is series fixes some problems that I spotted recently, secondly the
>>>> driver's code gets a cleanup. Please review and apply, thanks in advance!
>>>>
>>>> Changelog:
>>>>
>>>> v3: - In the review comment to v1 Michał Mirosław suggested that "Prevent
>>>>       race conditions on channel's freeing" does changes that deserve to
>>>>       be separated into two patches. I factored out and improved tasklet
>>>>       releasing into this new patch:
>>>>
>>>>         dmaengine: tegra-apb: Clean up tasklet releasing
>>>>
>>>>     - The "Fix use-after-free" patch got an improved commit message.
>>>>
>>>> v2: - I took another look at the driver and spotted few more things that
>>>>       could be improved, which resulted in these new patches:
>>>>
>>>>         dmaengine: tegra-apb: Remove runtime PM usage
>>>>         dmaengine: tegra-apb: Clean up suspend-resume
>>>>         dmaengine: tegra-apb: Add missing of_dma_controller_free
>>>>         dmaengine: tegra-apb: Allow to compile as a loadable kernel module
>>>>         dmaengine: tegra-apb: Remove MODULE_ALIAS
>>>>
>>>> Dmitry Osipenko (13):
>>>>   dmaengine: tegra-apb: Fix use-after-free
>>>>   dmaengine: tegra-apb: Implement synchronization callback
>>>>   dmaengine: tegra-apb: Prevent race conditions on channel's freeing
>>>>   dmaengine: tegra-apb: Clean up tasklet releasing
>>>>   dmaengine: tegra-apb: Prevent race conditions of tasklet vs free list
>>>>   dmaengine: tegra-apb: Use devm_platform_ioremap_resource
>>>>   dmaengine: tegra-apb: Use devm_request_irq
>>>>   dmaengine: tegra-apb: Fix coding style problems
>>>>   dmaengine: tegra-apb: Remove runtime PM usage
>>>>   dmaengine: tegra-apb: Clean up suspend-resume
>>>>   dmaengine: tegra-apb: Add missing of_dma_controller_free
>>>>   dmaengine: tegra-apb: Allow to compile as a loadable kernel module
>>>>   dmaengine: tegra-apb: Remove MODULE_ALIAS
>>>>
>>>>  drivers/dma/Kconfig           |   2 +-
>>>>  drivers/dma/tegra20-apb-dma.c | 481 ++++++++++++++++------------------
>>>>  2 files changed, 220 insertions(+), 263 deletions(-)
>>>
>>> Test results:
>>>   13 builds: 13 pass, 0 fail
>>>   12 boots:  11 pass, 1 fail
>>
>> I'm not sure how to interpret this result. Could you please explain what
>> that fail means?
> 
> Yeah, Jon and I have been discussing about whether to expose this as
> failure or not. Basically what I'm trying to do here is to provide
> automated test results. The way that I'm currently doing this is to run
> these patches through our internal test farm and if the tests succeed,
> send out the results and reply with a Tested-by: to all patches so that
> patchwork has a record of it.
> 
> So just the fact that the test results were sent means the tests passed.
> I do see now that that's not at all clear, so I'm going to have to tweak
> the summary a bit to clarify that.
> 
> I've also added something like this to the bottom of the summary:
> 
> 	Warnings:
> 	- 1 failure for board tegra186-p2771-0000 but tests passed
> 
> This is supposed to indicate that the one failure that you're seeing in
> the test results is an intermittent failure. Looking at the logs I see
> that at some point there was an intermittent boot failure for Jetson TX2
> but then the test farm rebooted the system and then it succeeded and ran
> the tests successfully.
> 
> So I guess in general this means that if you get that test summary and a
> list of Tested-by: replies to the patches, all is well. Unfortunately I
> don't really have a useful way of reporting failure, so I'm not sending
> out a summary in that case. That means you currently can't distinguish
> between whether the series hasn't been tested at all or whether it
> failed. Although, I have also started to use patchwork checks to track
> this in patchwork, so you could look at the patches in patchwork and see
> if they have been tested, and that does record success or failure.

The patchwork now says that all patches in this series failed.

Perhaps something needs to be done about filtering out the unimportant
intermittent noise.

>>>   38 tests:  38 pass, 0 fail
>>>
>>> Linux version: 5.5.0-rc5-gf9d40c056c0f
>>> Boards tested: tegra20-ventana, tegra30-cardhu-a04, tegra124-jetson-tk1,
>>>                tegra186-p2771-0000, tegra194-p2972-0000,
>>>                tegra210-p2371-2180
>>>
>>
>> Will be awesome to see the detailed testing results, at least console
>> log like it was with NVTB.
> 
> Yeah, I'm working on that. It's the only reason I'm not sending out
> failure reports because it would just say that things failed without
> giving you any indication about why.
> 
> Currently the plan is to upload more detailed test results to a public
> location (perhaps github, like nvtb used to) and provide a link to them
> in patchwork and the test summary.
> 
> Do you think that would be helpful?

Yes, the full log is absolutely necessary in a case of problem.

> Anything else you think would be useful to have in these reports?

Optionally, there should be instructions about how to reproduce problem,
which includes rootfs, toolchain and etc.

> Or anything about the above that you think is impractical for you as a contributor?

The intermittent noise should be impractical to report in the short
logs, telling that tests failed. But probably it won't hurt to have a
warning, like you suggested above, and then also to have everything
reported in the detailed log.

Re: [PATCH v3 09/13] dmaengine: tegra-apb: Remove runtime PM usage

[Vinod Koul]

On 07-01-20, 18:38, Jon Hunter wrote:
> 
> On 07/01/2020 17:12, Dmitry Osipenko wrote:
> > 07.01.2020 18:13, Jon Hunter пишет:
> >>
> >> On 06/01/2020 01:17, Dmitry Osipenko wrote:
> >>> There is no benefit from runtime PM usage for the APB DMA driver because
> >>> it enables clock at the time of channel's allocation and thus clock stays
> >>> enabled all the time in practice, secondly there is benefit from manually
> >>> disabled clock because hardware auto-gates it during idle by itself.
> >>
> >> This assumes that the channel is allocated during a driver
> >> initialisation. That may not always be the case. I believe audio is one
> >> case where channels are requested at the start of audio playback.
> > 
> > At least serial, I2C, SPI and T20 FUSE are permanently keeping channels
> > allocated, thus audio is an exception here. I don't think that it's
> > practical to assume that there is a real-world use-case where audio
> > driver is the only active DMA client.
> > 
> > The benefits of gating the DMA clock are also dim, do you have any
> > power-consumption numbers that show that it's really worth to care about
> > the clock-gating?
> 
> No, but at the same time, I really don't see the point in this. In fact,
> I think it is a step backwards. If we wanted to only enable clocks while
> DMA channels are active we could. So I request you drop this.

Agree, if pm is working fine with audio, doesnt make much sense to
remove. Future clients or updates to existing clients can be done to
make it dynamic..

-- 
~Vinod