From f4cdf7ca9a1fdcca413157df19753f388a5a224e Mon Sep 17 00:00:00 2001 From: Linus Torvalds Date: Wed, 19 Aug 2026 10:09:22 -0700 Subject: Merge tag 'media/v7.3-1' of git://git.kernel.org/pub/scm/linux/kernel/git/mchehab/linux-media Pull media updates from Mauro Carvalho Chehab: - v4l2-core: added ISP statistics support and per-block validation - v4l2-core: Allow unknown HDR10 white point and luminance - New camera sensors: Sony IMX678 and IMX471m, Himax HM1092 IR sensor - New codec: Milos: VPU v2.0 codec support - isp driver: gained support for Dreamchip RPPX1 ISP framework - vsp1 driver: gained support for RZ/T2H and RZ/N2H - Novalake driver: gained CVS support for new NVL hardware - dvb-core: fix feed leak on failed DMX_ADD_PID - several driver fixes, cleanups and minor improvements * tag 'media/v7.3-1' of git://git.kernel.org/pub/scm/linux/kernel/git/mchehab/linux-media: (308 commits) media: ipu-bridge: check all DMI entries when overriding sensor rotation media: v4l2-async: avoid deleting unlinked ASC entry on link error media: rzg2l-cru: Align bytesperline to hardware DMA stride requirement media: intel/ipu6: fix async notifier cleanup leak on parse error media: staging/ipu7: fix async notifier UAF on probe error path media: amd: isp4: fix self-deadlock in isp4sd_pwron_and_init() error path media: amd: isp4: release partial allocations in isp4if_alloc_fw_gpumem() media: rcar-isp: Fix VSPX reference leaks media: rcar-isp: Release ISPCORE resources media: i2c: imx415: Release runtime PM reference on VBLANK error media: i2c: imx415: Return test pattern write errors media: renesas: vsp1: Declare index variables in for loop statement media: renesas: vsp1: Make reset control optional to support platforms without a reset line media: dt-bindings: media: renesas,vsp1: Document RZ/T2H and RZ/N2H SoCs media: dt-bindings: media: renesas,fcp: Document RZ/T2H and RZ/N2H SoCs media: nxp: imx8-isi: Add additional 32-bit RGB format support media: nxp: imx8-isi: Add 16-bit raw Bayer format support media: nxp: imx8-isi: Implement per-stream reference counting for multiplexed streams media: nxp: imx8-isi: Use BIT_ULL() for 64-bit stream masks media: nxp: imx8-isi: Correct color map between V4L2 and ISI ... --- samples/kfifo/dma-example.c | 144 ++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 144 insertions(+) create mode 100644 samples/kfifo/dma-example.c (limited to 'samples/kfifo/dma-example.c') diff --git a/samples/kfifo/dma-example.c b/samples/kfifo/dma-example.c new file mode 100644 index 000000000..8076ac410 --- /dev/null +++ b/samples/kfifo/dma-example.c @@ -0,0 +1,144 @@ +// SPDX-License-Identifier: GPL-2.0-only +/* + * Sample fifo dma implementation + * + * Copyright (C) 2010 Stefani Seibold + */ + +#include +#include +#include +#include +#include + +/* + * This module shows how to handle fifo dma operations. + */ + +/* fifo size in elements (bytes) */ +#define FIFO_SIZE 32 + +static struct kfifo fifo; + +static int __init example_init(void) +{ + int i; + unsigned int ret; + unsigned int nents; + struct scatterlist sg[10]; + + printk(KERN_INFO "DMA fifo test start\n"); + + if (kfifo_alloc(&fifo, FIFO_SIZE, GFP_KERNEL)) { + printk(KERN_WARNING "error kfifo_alloc\n"); + return -ENOMEM; + } + + printk(KERN_INFO "queue size: %u\n", kfifo_size(&fifo)); + + kfifo_in(&fifo, "test", 4); + + for (i = 0; i != 9; i++) + kfifo_put(&fifo, i); + + /* kick away first byte */ + kfifo_skip(&fifo); + + printk(KERN_INFO "queue len: %u\n", kfifo_len(&fifo)); + + /* + * Configure the kfifo buffer to receive data from DMA input. + * + * .--------------------------------------. + * | 0 | 1 | 2 | ... | 12 | 13 | ... | 31 | + * |---|------------------|---------------| + * \_/ \________________/ \_____________/ + * \ \ \ + * \ \_allocated data \ + * \_*free space* \_*free space* + * + * We need two different SG entries: one for the free space area at the + * end of the kfifo buffer (19 bytes) and another for the first free + * byte at the beginning, after the kfifo_skip(). + */ + sg_init_table(sg, ARRAY_SIZE(sg)); + nents = kfifo_dma_in_prepare(&fifo, sg, ARRAY_SIZE(sg), FIFO_SIZE); + printk(KERN_INFO "DMA sgl entries: %d\n", nents); + if (!nents) { + /* fifo is full and no sgl was created */ + printk(KERN_WARNING "error kfifo_dma_in_prepare\n"); + return -EIO; + } + + /* receive data */ + printk(KERN_INFO "scatterlist for receive:\n"); + for (i = 0; i < nents; i++) { + printk(KERN_INFO + "sg[%d] -> " + "page %p offset 0x%.8x length 0x%.8x\n", + i, sg_page(&sg[i]), sg[i].offset, sg[i].length); + + if (sg_is_last(&sg[i])) + break; + } + + /* put here your code to setup and exectute the dma operation */ + /* ... */ + + /* example: zero bytes received */ + ret = 0; + + /* finish the dma operation and update the received data */ + kfifo_dma_in_finish(&fifo, ret); + + /* Prepare to transmit data, example: 8 bytes */ + nents = kfifo_dma_out_prepare(&fifo, sg, ARRAY_SIZE(sg), 8); + printk(KERN_INFO "DMA sgl entries: %d\n", nents); + if (!nents) { + /* no data was available and no sgl was created */ + printk(KERN_WARNING "error kfifo_dma_out_prepare\n"); + return -EIO; + } + + printk(KERN_INFO "scatterlist for transmit:\n"); + for (i = 0; i < nents; i++) { + printk(KERN_INFO + "sg[%d] -> " + "page %p offset 0x%.8x length 0x%.8x\n", + i, sg_page(&sg[i]), sg[i].offset, sg[i].length); + + if (sg_is_last(&sg[i])) + break; + } + + /* put here your code to setup and exectute the dma operation */ + /* ... */ + + /* example: 5 bytes transmitted */ + ret = 5; + + /* finish the dma operation and update the transmitted data */ + kfifo_dma_out_finish(&fifo, ret); + + ret = kfifo_len(&fifo); + printk(KERN_INFO "queue len: %u\n", kfifo_len(&fifo)); + + if (ret != 7) { + printk(KERN_WARNING "size mismatch: test failed"); + return -EIO; + } + printk(KERN_INFO "test passed\n"); + + return 0; +} + +static void __exit example_exit(void) +{ + kfifo_free(&fifo); +} + +module_init(example_init); +module_exit(example_exit); +MODULE_DESCRIPTION("Sample fifo dma implementation"); +MODULE_LICENSE("GPL"); +MODULE_AUTHOR("Stefani Seibold "); -- cgit v1.3.1