drivers/dma/loongson/loongson2-apb-cmc-dma.c:677:6-16: WARNING: Unsigned expression compared with zero: lchan -> irq < 0 (fwd)

---------- Forwarded message ----------
Date: Sat, 15 Aug 2026 22:52:36 +0800
From: kernel test robot <[email protected]>
To: [email protected]
Cc: [email protected], Julia Lawall <[email protected]>
Subject: drivers/dma/loongson/loongson2-apb-cmc-dma.c:677:6-16: WARNING:
    Unsigned expression compared with zero: lchan -> irq < 0

BCC: [email protected]
CC: [email protected]
CC: [email protected]
TO: Binbin Zhou <[email protected]>
CC: Vinod Koul <[email protected]>
CC: Frank Li <[email protected]>
CC: Huacai Chen <[email protected]>

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/[email protected]/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 <[email protected]>
| Reported-by: Julia Lawall <[email protected]>
| Closes: https://lore.kernel.org/r/[email protected]/

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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