drivers/dma/loongson/loongson2-apb-cmc-dma.c:677:6-16: WARNING: Unsigned expression compared with zero: lchan -> irq < 0 (fwd)
From: Julia Lawall
Date: Sat Aug 15 2026 - 14:10:36 EST
---------- Forwarded message ----------
Date: Sat, 15 Aug 2026 22:52:36 +0800
From: kernel test robot <lkp@xxxxxxxxx>
To: oe-kbuild@xxxxxxxxxxxxxxx
Cc: lkp@xxxxxxxxx, Julia Lawall <julia.lawall@xxxxxxxx>
Subject: drivers/dma/loongson/loongson2-apb-cmc-dma.c:677:6-16: WARNING:
Unsigned expression compared with zero: lchan -> irq < 0
BCC: lkp@xxxxxxxxx
CC: oe-kbuild-all@xxxxxxxxxxxxxxx
CC: linux-kernel@xxxxxxxxxxxxxxx
TO: Binbin Zhou <zhoubinbin@xxxxxxxxxxx>
CC: Vinod Koul <vkoul@xxxxxxxxxx>
CC: Frank Li <Frank.Li@xxxxxxx>
CC: Huacai Chen <chenhuacai@xxxxxxxxxxx>
tree: https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git master
head: 15ef2f78c49d20d53ec7c0f1c9b40b02e089f2d6
commit: 1c0028e725f156ebabe68b0025f9c8e7a6170ffd dmaengine: loongson: New driver for the Loongson Multi-Channel DMA controller
date: 5 months ago
:::::: branch date: 10 hours ago
:::::: commit date: 5 months ago
config: powerpc-randconfig-r053-20260812 (https://download.01.org/0day-ci/archive/20260815/202608152230.p20WPlS0-lkp@xxxxxxxxx/config)
compiler: clang version 24.0.0git (https://github.com/llvm/llvm-project 12df34b8469b8095359de8c249cb1b2753fadeea)
If you fix the issue in a separate patch/commit (i.e. not just a new version of
the same patch/commit), kindly add following tags
| Fixes: 1c0028e725f1 ("dmaengine: loongson: New driver for the Loongson Multi-Channel DMA controller")
| Reported-by: kernel test robot <lkp@xxxxxxxxx>
| Reported-by: Julia Lawall <julia.lawall@xxxxxxxx>
| Closes: https://lore.kernel.org/r/202608152230.p20WPlS0-lkp@xxxxxxxxx/
cocci warnings: (new ones prefixed by >>)
>> drivers/dma/loongson/loongson2-apb-cmc-dma.c:677:6-16: WARNING: Unsigned expression compared with zero: lchan -> irq < 0
vim +677 drivers/dma/loongson/loongson2-apb-cmc-dma.c
1c0028e725f156 Binbin Zhou 2026-03-07 601
1c0028e725f156 Binbin Zhou 2026-03-07 602 static int loongson2_cmc_dma_probe(struct platform_device *pdev)
1c0028e725f156 Binbin Zhou 2026-03-07 603 {
1c0028e725f156 Binbin Zhou 2026-03-07 604 const struct loongson2_cmc_dma_config *config;
1c0028e725f156 Binbin Zhou 2026-03-07 605 struct loongson2_cmc_dma_chan *lchan;
1c0028e725f156 Binbin Zhou 2026-03-07 606 struct loongson2_cmc_dma_dev *lddev;
1c0028e725f156 Binbin Zhou 2026-03-07 607 struct device *dev = &pdev->dev;
1c0028e725f156 Binbin Zhou 2026-03-07 608 struct dma_device *ddev;
1c0028e725f156 Binbin Zhou 2026-03-07 609 u32 nr_chans, i;
1c0028e725f156 Binbin Zhou 2026-03-07 610 int ret;
1c0028e725f156 Binbin Zhou 2026-03-07 611
1c0028e725f156 Binbin Zhou 2026-03-07 612 config = (const struct loongson2_cmc_dma_config *)device_get_match_data(dev);
1c0028e725f156 Binbin Zhou 2026-03-07 613 if (!config)
1c0028e725f156 Binbin Zhou 2026-03-07 614 return -EINVAL;
1c0028e725f156 Binbin Zhou 2026-03-07 615
1c0028e725f156 Binbin Zhou 2026-03-07 616 ret = device_property_read_u32(dev, "dma-channels", &nr_chans);
1c0028e725f156 Binbin Zhou 2026-03-07 617 if (ret || nr_chans > config->max_channels) {
1c0028e725f156 Binbin Zhou 2026-03-07 618 dev_err(dev, "missing or invalid dma-channels property\n");
1c0028e725f156 Binbin Zhou 2026-03-07 619 nr_chans = config->max_channels;
1c0028e725f156 Binbin Zhou 2026-03-07 620 }
1c0028e725f156 Binbin Zhou 2026-03-07 621
1c0028e725f156 Binbin Zhou 2026-03-07 622 lddev = devm_kzalloc(dev, struct_size(lddev, chan, nr_chans), GFP_KERNEL);
1c0028e725f156 Binbin Zhou 2026-03-07 623 if (!lddev)
1c0028e725f156 Binbin Zhou 2026-03-07 624 return -ENOMEM;
1c0028e725f156 Binbin Zhou 2026-03-07 625
1c0028e725f156 Binbin Zhou 2026-03-07 626 lddev->base = devm_platform_ioremap_resource(pdev, 0);
1c0028e725f156 Binbin Zhou 2026-03-07 627 if (IS_ERR(lddev->base))
1c0028e725f156 Binbin Zhou 2026-03-07 628 return PTR_ERR(lddev->base);
1c0028e725f156 Binbin Zhou 2026-03-07 629
1c0028e725f156 Binbin Zhou 2026-03-07 630 platform_set_drvdata(pdev, lddev);
1c0028e725f156 Binbin Zhou 2026-03-07 631 lddev->nr_channels = nr_chans;
1c0028e725f156 Binbin Zhou 2026-03-07 632 lddev->chan_reg_offset = config->chan_reg_offset;
1c0028e725f156 Binbin Zhou 2026-03-07 633
1c0028e725f156 Binbin Zhou 2026-03-07 634 lddev->dma_clk = devm_clk_get_optional_enabled(dev, NULL);
1c0028e725f156 Binbin Zhou 2026-03-07 635 if (IS_ERR(lddev->dma_clk))
1c0028e725f156 Binbin Zhou 2026-03-07 636 return dev_err_probe(dev, PTR_ERR(lddev->dma_clk), "Failed to get dma clock\n");
1c0028e725f156 Binbin Zhou 2026-03-07 637
1c0028e725f156 Binbin Zhou 2026-03-07 638 ddev = &lddev->ddev;
1c0028e725f156 Binbin Zhou 2026-03-07 639 ddev->dev = dev;
1c0028e725f156 Binbin Zhou 2026-03-07 640
1c0028e725f156 Binbin Zhou 2026-03-07 641 dma_cap_zero(ddev->cap_mask);
1c0028e725f156 Binbin Zhou 2026-03-07 642 dma_cap_set(DMA_SLAVE, ddev->cap_mask);
1c0028e725f156 Binbin Zhou 2026-03-07 643 dma_cap_set(DMA_PRIVATE, ddev->cap_mask);
1c0028e725f156 Binbin Zhou 2026-03-07 644 dma_cap_set(DMA_CYCLIC, ddev->cap_mask);
1c0028e725f156 Binbin Zhou 2026-03-07 645
1c0028e725f156 Binbin Zhou 2026-03-07 646 ddev->device_free_chan_resources = loongson2_cmc_dma_free_chan_resources;
1c0028e725f156 Binbin Zhou 2026-03-07 647 ddev->device_config = loongson2_cmc_dma_slave_config;
1c0028e725f156 Binbin Zhou 2026-03-07 648 ddev->device_prep_slave_sg = loongson2_cmc_dma_prep_slave_sg;
1c0028e725f156 Binbin Zhou 2026-03-07 649 ddev->device_prep_dma_cyclic = loongson2_cmc_dma_prep_dma_cyclic;
1c0028e725f156 Binbin Zhou 2026-03-07 650 ddev->device_issue_pending = loongson2_cmc_dma_issue_pending;
1c0028e725f156 Binbin Zhou 2026-03-07 651 ddev->device_synchronize = loongson2_cmc_dma_synchronize;
1c0028e725f156 Binbin Zhou 2026-03-07 652 ddev->device_tx_status = loongson2_cmc_dma_tx_status;
1c0028e725f156 Binbin Zhou 2026-03-07 653 ddev->device_terminate_all = loongson2_cmc_dma_terminate_all;
1c0028e725f156 Binbin Zhou 2026-03-07 654
1c0028e725f156 Binbin Zhou 2026-03-07 655 ddev->max_sg_burst = LOONSON2_CMCDMA_MAX_DATA_ITEMS;
1c0028e725f156 Binbin Zhou 2026-03-07 656 ddev->src_addr_widths = LOONGSON2_CMCDMA_BUSWIDTHS;
1c0028e725f156 Binbin Zhou 2026-03-07 657 ddev->dst_addr_widths = LOONGSON2_CMCDMA_BUSWIDTHS;
1c0028e725f156 Binbin Zhou 2026-03-07 658 ddev->directions = BIT(DMA_DEV_TO_MEM) | BIT(DMA_MEM_TO_DEV);
1c0028e725f156 Binbin Zhou 2026-03-07 659 INIT_LIST_HEAD(&ddev->channels);
1c0028e725f156 Binbin Zhou 2026-03-07 660
1c0028e725f156 Binbin Zhou 2026-03-07 661 for (i = 0; i < nr_chans; i++) {
1c0028e725f156 Binbin Zhou 2026-03-07 662 lchan = &lddev->chan[i];
1c0028e725f156 Binbin Zhou 2026-03-07 663
1c0028e725f156 Binbin Zhou 2026-03-07 664 lchan->id = i;
1c0028e725f156 Binbin Zhou 2026-03-07 665 lchan->vchan.desc_free = loongson2_cmc_dma_desc_free;
1c0028e725f156 Binbin Zhou 2026-03-07 666 vchan_init(&lchan->vchan, ddev);
1c0028e725f156 Binbin Zhou 2026-03-07 667 }
1c0028e725f156 Binbin Zhou 2026-03-07 668
1c0028e725f156 Binbin Zhou 2026-03-07 669 ret = dmaenginem_async_device_register(ddev);
1c0028e725f156 Binbin Zhou 2026-03-07 670 if (ret)
1c0028e725f156 Binbin Zhou 2026-03-07 671 return dev_err_probe(dev, ret, "Failed to register DMA engine device.\n");
1c0028e725f156 Binbin Zhou 2026-03-07 672
1c0028e725f156 Binbin Zhou 2026-03-07 673 for (i = 0; i < nr_chans; i++) {
1c0028e725f156 Binbin Zhou 2026-03-07 674 lchan = &lddev->chan[i];
1c0028e725f156 Binbin Zhou 2026-03-07 675
1c0028e725f156 Binbin Zhou 2026-03-07 676 lchan->irq = platform_get_irq(pdev, i);
1c0028e725f156 Binbin Zhou 2026-03-07 @677 if (lchan->irq < 0)
1c0028e725f156 Binbin Zhou 2026-03-07 678 return lchan->irq;
1c0028e725f156 Binbin Zhou 2026-03-07 679
1c0028e725f156 Binbin Zhou 2026-03-07 680 ret = devm_request_irq(dev, lchan->irq, loongson2_cmc_dma_chan_irq, IRQF_SHARED,
1c0028e725f156 Binbin Zhou 2026-03-07 681 dev_name(chan2dev(lchan)), lchan);
1c0028e725f156 Binbin Zhou 2026-03-07 682 if (ret)
1c0028e725f156 Binbin Zhou 2026-03-07 683 return ret;
1c0028e725f156 Binbin Zhou 2026-03-07 684 }
1c0028e725f156 Binbin Zhou 2026-03-07 685
1c0028e725f156 Binbin Zhou 2026-03-07 686 ret = loongson2_cmc_dma_acpi_controller_register(lddev);
1c0028e725f156 Binbin Zhou 2026-03-07 687 if (ret)
1c0028e725f156 Binbin Zhou 2026-03-07 688 return dev_err_probe(dev, ret, "Failed to register dma controller with ACPI.\n");
1c0028e725f156 Binbin Zhou 2026-03-07 689
1c0028e725f156 Binbin Zhou 2026-03-07 690 ret = loongson2_cmc_dma_of_controller_register(lddev);
1c0028e725f156 Binbin Zhou 2026-03-07 691 if (ret)
1c0028e725f156 Binbin Zhou 2026-03-07 692 return dev_err_probe(dev, ret, "Failed to register dma controller with FDT.\n");
1c0028e725f156 Binbin Zhou 2026-03-07 693
1c0028e725f156 Binbin Zhou 2026-03-07 694 dev_info(dev, "Loongson-2 Multi-Channel DMA Controller registered successfully.\n");
1c0028e725f156 Binbin Zhou 2026-03-07 695
1c0028e725f156 Binbin Zhou 2026-03-07 696 return 0;
1c0028e725f156 Binbin Zhou 2026-03-07 697 }
1c0028e725f156 Binbin Zhou 2026-03-07 698
--
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