samples: drivers: dma: add dma_scatter_gather sample by CijaSathish-AlifSemi · Pull Request #628 · alifsemi/sdk-alif

CijaSathish-AlifSemi · 2026-03-26T00:54:33Z

Add memory-to-memory scatter-gather DMA test application for Alif Ensemble and Balletto devices. Tests block chaining support added to the PL330 DMA driver.

Depends : alifsemi/zephyr_alif#442

samples/drivers/dma_scatter_gather/snippets/alif-dma/alif_b1_dk_rtss_he.overlay

samples/drivers/dma_scatter_gather/src/main.c

samples/drivers/dma_scatter_gather/CMakeLists.txt

samples/drivers/dma_scatter_gather/prj.conf

samples/drivers/dma_scatter_gather/sample.yaml

Copilot

Pull request overview

Adds a new Zephyr sample to exercise PL330 scatter-gather (block chaining) in a memory-to-memory DMA transfer on Alif platforms.

Changes:

Introduces a DMA scatter-gather test application that chains 3 DMA blocks and verifies results.
Adds an alif-dma snippet with board-specific overlays to provide a test-dma alias and enable the chosen DMA instance.
Adds standard sample metadata/build files (CMake, prj.conf, README, sample.yaml).

Reviewed changes

Copilot reviewed 12 out of 12 changed files in this pull request and generated 8 comments.

Show a summary per file

File	Description
samples/drivers/dma_scatter_gather/src/main.c	Implements the scatter-gather DMA test logic, callback, and buffer verification.
samples/drivers/dma_scatter_gather/snippets/alif-dma/snippet.yml	Provides snippet configuration to apply the right overlay per Alif board/variant.
samples/drivers/dma_scatter_gather/snippets/alif-dma/*.overlay	Adds `test-dma` alias and enables the selected DMA controller instance.
samples/drivers/dma_scatter_gather/sample.yaml	Registers the sample as a Twister test.
samples/drivers/dma_scatter_gather/prj.conf	Enables DMA + PL330 and logging/console settings for the sample.
samples/drivers/dma_scatter_gather/README.rst	Documents purpose, build command, and expected output.
samples/drivers/dma_scatter_gather/CMakeLists.txt	Builds the sample app source.

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samples/drivers/dma_scatter_gather/src/main.c

samples/drivers/dma_scatter_gather/sample.yaml

samples/drivers/dma_scatter_gather/src/main.c

CijaSathish-AlifSemi · 2026-03-30T19:54:52Z

@petrih-alifsemi addressed all the changes. Please check..thanks

Copilot

Pull request overview

Copilot reviewed 12 out of 12 changed files in this pull request and generated 2 comments.

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Copilot · 2026-03-31T17:50:49Z

samples/drivers/dma_scatter_gather/src/main.c

+	/* Setup test data */
+	fill_buffer(src1, BLOCK1_SIZE, 0xA0);
+	fill_buffer(src2, BLOCK2_SIZE, 0xB0);
+	fill_buffer(src3, BLOCK3_SIZE, 0xC0);
+	clear_buffers();
+


On targets with data cache enabled, this sample can report mismatches because the DMA engine may read stale source data and the CPU may read stale destination data. Consider adding cache maintenance around the transfer (e.g., under CONFIG_DCACHE: flush/invalidate src buffers and the dma_block_config array before dma_start, and invalidate dst buffers after completion before memcmp), and include the appropriate cache header.

Copilot · 2026-03-31T17:50:49Z

samples/drivers/dma_scatter_gather/src/main.c

+	struct dma_config dma_cfg = {
+		.channel_direction = MEMORY_TO_MEMORY,
+		.source_data_size = 4,
+		.dest_data_size = 4,
+		.source_burst_length = 1,
+		.dest_burst_length = 1,	/* burst=1 keeps alignment simple for this test */
+		.dma_slot = 0,
+		.block_count = 3,
+		.head_block = head_block,
+		.dma_callback = dma_callback,
+		.user_data = NULL,
+	};
+


dma_cfg.block_count is hard-coded to 3; since the blocks are already in a fixed-size array in this sample, using ARRAY_SIZE(blocks) (or an equivalent constant derived from the array) would keep the configuration consistent if the number of blocks changes later.

Suggested change

struct dma_config dma_cfg = {

.channel_direction = MEMORY_TO_MEMORY,

.source_data_size = 4,

.dest_data_size = 4,

.source_burst_length = 1,

.dest_burst_length = 1, /* burst=1 keeps alignment simple for this test */

.dma_slot = 0,

.block_count = 3,

.head_block = head_block,

.dma_callback = dma_callback,

.user_data = NULL,

};

struct dma_block_config *blk;

uint32_t block_count = 0U;

struct dma_config dma_cfg = { 0 };

/* Count the number of scatter-gather blocks starting from head_block */

for (blk = head_block; blk != NULL; blk = blk->next_block) {

block_count++;

}

dma_cfg.channel_direction = MEMORY_TO_MEMORY;

dma_cfg.source_data_size = 4;

dma_cfg.dest_data_size = 4;

dma_cfg.source_burst_length = 1;

dma_cfg.dest_burst_length = 1; /* burst=1 keeps alignment simple for this test */

dma_cfg.dma_slot = 0;

dma_cfg.block_count = block_count;

dma_cfg.head_block = head_block;

dma_cfg.dma_callback = dma_callback;

dma_cfg.user_data = NULL;

samples/drivers/dma_scatter_gather/README.rst

petrih-alifsemi · 2026-04-01T05:59:45Z

Is this related to alifsemi/zephyr_alif#442?

sudhir-alifsemi · 2026-04-01T06:32:31Z

Is this related to alifsemi/zephyr_alif#442?

Yes

petrih-alifsemi

West update is needed

CijaSathish-AlifSemi · 2026-04-01T23:29:41Z

@petrih-alifsemi
Once the driver PR is merged, I'll update west.yml to the new main revision (and CI should pass)

VeijoPesonen

Requires manifest update. Otherwise looks good to me.

west.yml

Add memory-to-memory scatter-gather DMA test application for Alif Ensemble and Balletto devices. Tests block chaining support added to the PL330 DMA driver. Signed-off-by: Cija Sathishkumar <cija.sathishkumar@alifsemi.com>

CijaSathish-AlifSemi requested review from BhupeshKharwa-AlifSemi and sudhir-alifsemi March 26, 2026 00:54

CijaSathish-AlifSemi requested a review from RupeshKumar-AlifSemi as a code owner March 26, 2026 00:54

VeijoPesonen requested review from a team, JuhoEskeli-AlifSemi and petrih-alifsemi March 26, 2026 14:16

petrih-alifsemi requested changes Mar 27, 2026

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RupeshKumar-AlifSemi requested a review from Copilot March 27, 2026 08:15

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CijaSathish-AlifSemi force-pushed the feature/pl330-scatter-gather branch 2 times, most recently from 557a109 to 813991f Compare March 30, 2026 19:16

CijaSathish-AlifSemi requested review from Copilot and petrih-alifsemi March 31, 2026 17:44

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petrih-alifsemi approved these changes Mar 31, 2026

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VeijoPesonen reviewed Apr 1, 2026

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samples/drivers/dma_scatter_gather/README.rst Outdated Show resolved Hide resolved

sudhir-alifsemi added the do not merge Work in progress label Apr 1, 2026

petrih-alifsemi requested changes Apr 1, 2026

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CijaSathish-AlifSemi force-pushed the feature/pl330-scatter-gather branch from 813991f to 263fcdd Compare April 1, 2026 22:23

CijaSathish-AlifSemi requested review from Anilkumar-Alifsemi and AnttiKauppila-AlifSemi as code owners April 1, 2026 22:23

CijaSathish-AlifSemi force-pushed the feature/pl330-scatter-gather branch from 263fcdd to bae7700 Compare April 1, 2026 23:04

CijaSathish-AlifSemi requested review from VeijoPesonen and petrih-alifsemi April 1, 2026 23:05

VeijoPesonen requested changes Apr 2, 2026

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CijaSathish-AlifSemi force-pushed the feature/pl330-scatter-gather branch from bae7700 to 3fb9e7b Compare April 2, 2026 17:09

samples: drivers: dma: add dma_scatter_gather sample

be86c3f

Add memory-to-memory scatter-gather DMA test application for Alif Ensemble and Balletto devices. Tests block chaining support added to the PL330 DMA driver. Signed-off-by: Cija Sathishkumar <cija.sathishkumar@alifsemi.com>

CijaSathish-AlifSemi force-pushed the feature/pl330-scatter-gather branch from 3fb9e7b to be86c3f Compare April 2, 2026 18:01

-	struct dma_config dma_cfg = {
-		.channel_direction = MEMORY_TO_MEMORY,
-		.source_data_size = 4,
-		.dest_data_size = 4,
-		.source_burst_length = 1,
-		.dest_burst_length = 1,	/* burst=1 keeps alignment simple for this test */
-		.dma_slot = 0,
-		.block_count = 3,
-		.head_block = head_block,
-		.dma_callback = dma_callback,
-		.user_data = NULL,
-	};
+	struct dma_block_config *blk;
+	uint32_t block_count = 0U;
+	struct dma_config dma_cfg = { 0 };
+	/* Count the number of scatter-gather blocks starting from head_block */
+	for (blk = head_block; blk != NULL; blk = blk->next_block) {
+		block_count++;
+	}
+	dma_cfg.channel_direction   = MEMORY_TO_MEMORY;
+	dma_cfg.source_data_size    = 4;
+	dma_cfg.dest_data_size      = 4;
+	dma_cfg.source_burst_length = 1;
+	dma_cfg.dest_burst_length   = 1;	/* burst=1 keeps alignment simple for this test */
+	dma_cfg.dma_slot            = 0;
+	dma_cfg.block_count         = block_count;
+	dma_cfg.head_block          = head_block;
+	dma_cfg.dma_callback        = dma_callback;
+	dma_cfg.user_data           = NULL;

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CijaSathish-AlifSemi commented Mar 30, 2026

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CijaSathish-AlifSemi commented Mar 26, 2026 •

edited by sudhir-alifsemi

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