Re: [PATCH 6/8] nvmet: pci-epf: Use dmaengine_prep_slave_single_config() API

Hi Frank,

kernel test robot noticed the following build warnings:

[auto build test WARNING on bc04acf4aeca588496124a6cf54bfce3db327039]

url:    https://github.com/intel-lab-lkp/linux/commits/Frank-Li/dmaengine-Add-API-to-combine-configuration-and-preparation-sg-and-single/20251209-011820
base:   bc04acf4aeca588496124a6cf54bfce3db327039
patch link:    https://lore.kernel.org/r/20251208-dma_prep_config-v1-6-53490c5e1e2a%40nxp.com
patch subject: [PATCH 6/8] nvmet: pci-epf: Use dmaengine_prep_slave_single_config() API
config: i386-allmodconfig (https://download.01.org/0day-ci/archive/20251211/[email protected]/config)
compiler: gcc-14 (Debian 14.2.0-19) 14.2.0
reproduce (this is a W=1 build): (https://download.01.org/0day-ci/archive/20251211/[email protected]/reproduce)

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
| Reported-by: kernel test robot <[email protected]>
| Closes: https://lore.kernel.org/oe-kbuild-all/[email protected]/

All warnings (new ones prefixed by >>):

   drivers/nvme/target/pci-epf.c: In function 'nvmet_pci_epf_dma_transfer':
>> drivers/nvme/target/pci-epf.c:369:23: warning: variable 'lock' set but not used [-Wunused-but-set-variable]
     369 |         struct mutex *lock;
         |                       ^~~~


vim +/lock +369 drivers/nvme/target/pci-epf.c

0faa0fe6f90ea5 Damien Le Moal 2025-01-04  357  
0faa0fe6f90ea5 Damien Le Moal 2025-01-04  358  static int nvmet_pci_epf_dma_transfer(struct nvmet_pci_epf *nvme_epf,
0faa0fe6f90ea5 Damien Le Moal 2025-01-04  359  		struct nvmet_pci_epf_segment *seg, enum dma_data_direction dir)
0faa0fe6f90ea5 Damien Le Moal 2025-01-04  360  {
0faa0fe6f90ea5 Damien Le Moal 2025-01-04  361  	struct pci_epf *epf = nvme_epf->epf;
0faa0fe6f90ea5 Damien Le Moal 2025-01-04  362  	struct dma_async_tx_descriptor *desc;
0faa0fe6f90ea5 Damien Le Moal 2025-01-04  363  	struct dma_slave_config sconf = {};
0faa0fe6f90ea5 Damien Le Moal 2025-01-04  364  	struct device *dev = &epf->dev;
0faa0fe6f90ea5 Damien Le Moal 2025-01-04  365  	struct device *dma_dev;
0faa0fe6f90ea5 Damien Le Moal 2025-01-04  366  	struct dma_chan *chan;
0faa0fe6f90ea5 Damien Le Moal 2025-01-04  367  	dma_cookie_t cookie;
0faa0fe6f90ea5 Damien Le Moal 2025-01-04  368  	dma_addr_t dma_addr;
0faa0fe6f90ea5 Damien Le Moal 2025-01-04 @369  	struct mutex *lock;
0faa0fe6f90ea5 Damien Le Moal 2025-01-04  370  	int ret;
0faa0fe6f90ea5 Damien Le Moal 2025-01-04  371  
0faa0fe6f90ea5 Damien Le Moal 2025-01-04  372  	switch (dir) {
0faa0fe6f90ea5 Damien Le Moal 2025-01-04  373  	case DMA_FROM_DEVICE:
0faa0fe6f90ea5 Damien Le Moal 2025-01-04  374  		lock = &nvme_epf->dma_rx_lock;
0faa0fe6f90ea5 Damien Le Moal 2025-01-04  375  		chan = nvme_epf->dma_rx_chan;
0faa0fe6f90ea5 Damien Le Moal 2025-01-04  376  		sconf.direction = DMA_DEV_TO_MEM;
0faa0fe6f90ea5 Damien Le Moal 2025-01-04  377  		sconf.src_addr = seg->pci_addr;
0faa0fe6f90ea5 Damien Le Moal 2025-01-04  378  		break;
0faa0fe6f90ea5 Damien Le Moal 2025-01-04  379  	case DMA_TO_DEVICE:
0faa0fe6f90ea5 Damien Le Moal 2025-01-04  380  		lock = &nvme_epf->dma_tx_lock;
0faa0fe6f90ea5 Damien Le Moal 2025-01-04  381  		chan = nvme_epf->dma_tx_chan;
0faa0fe6f90ea5 Damien Le Moal 2025-01-04  382  		sconf.direction = DMA_MEM_TO_DEV;
0faa0fe6f90ea5 Damien Le Moal 2025-01-04  383  		sconf.dst_addr = seg->pci_addr;
0faa0fe6f90ea5 Damien Le Moal 2025-01-04  384  		break;
0faa0fe6f90ea5 Damien Le Moal 2025-01-04  385  	default:
0faa0fe6f90ea5 Damien Le Moal 2025-01-04  386  		return -EINVAL;
0faa0fe6f90ea5 Damien Le Moal 2025-01-04  387  	}
0faa0fe6f90ea5 Damien Le Moal 2025-01-04  388  
0faa0fe6f90ea5 Damien Le Moal 2025-01-04  389  	dma_dev = dmaengine_get_dma_device(chan);
0faa0fe6f90ea5 Damien Le Moal 2025-01-04  390  	dma_addr = dma_map_single(dma_dev, seg->buf, seg->length, dir);
0faa0fe6f90ea5 Damien Le Moal 2025-01-04  391  	ret = dma_mapping_error(dma_dev, dma_addr);
0faa0fe6f90ea5 Damien Le Moal 2025-01-04  392  	if (ret)
f9f42a84df49d9 Frank Li       2025-12-08  393  		return ret;
0faa0fe6f90ea5 Damien Le Moal 2025-01-04  394  
f9f42a84df49d9 Frank Li       2025-12-08  395  	desc = dmaengine_prep_slave_single_config(chan, dma_addr, seg->length,
f9f42a84df49d9 Frank Li       2025-12-08  396  						  sconf.direction,
f9f42a84df49d9 Frank Li       2025-12-08  397  						  DMA_CTRL_ACK,
f9f42a84df49d9 Frank Li       2025-12-08  398  						  &sconf);
0faa0fe6f90ea5 Damien Le Moal 2025-01-04  399  	if (!desc) {
0faa0fe6f90ea5 Damien Le Moal 2025-01-04  400  		dev_err(dev, "Failed to prepare DMA\n");
0faa0fe6f90ea5 Damien Le Moal 2025-01-04  401  		ret = -EIO;
0faa0fe6f90ea5 Damien Le Moal 2025-01-04  402  		goto unmap;
0faa0fe6f90ea5 Damien Le Moal 2025-01-04  403  	}
0faa0fe6f90ea5 Damien Le Moal 2025-01-04  404  
0faa0fe6f90ea5 Damien Le Moal 2025-01-04  405  	cookie = dmaengine_submit(desc);
0faa0fe6f90ea5 Damien Le Moal 2025-01-04  406  	ret = dma_submit_error(cookie);
0faa0fe6f90ea5 Damien Le Moal 2025-01-04  407  	if (ret) {
0faa0fe6f90ea5 Damien Le Moal 2025-01-04  408  		dev_err(dev, "Failed to do DMA submit (err=%d)\n", ret);
0faa0fe6f90ea5 Damien Le Moal 2025-01-04  409  		goto unmap;
0faa0fe6f90ea5 Damien Le Moal 2025-01-04  410  	}
0faa0fe6f90ea5 Damien Le Moal 2025-01-04  411  
0faa0fe6f90ea5 Damien Le Moal 2025-01-04  412  	if (dma_sync_wait(chan, cookie) != DMA_COMPLETE) {
0faa0fe6f90ea5 Damien Le Moal 2025-01-04  413  		dev_err(dev, "DMA transfer failed\n");
0faa0fe6f90ea5 Damien Le Moal 2025-01-04  414  		ret = -EIO;
0faa0fe6f90ea5 Damien Le Moal 2025-01-04  415  	}
0faa0fe6f90ea5 Damien Le Moal 2025-01-04  416  
0faa0fe6f90ea5 Damien Le Moal 2025-01-04  417  unmap:
0faa0fe6f90ea5 Damien Le Moal 2025-01-04  418  	dma_unmap_single(dma_dev, dma_addr, seg->length, dir);
0faa0fe6f90ea5 Damien Le Moal 2025-01-04  419  
0faa0fe6f90ea5 Damien Le Moal 2025-01-04  420  	return ret;
0faa0fe6f90ea5 Damien Le Moal 2025-01-04  421  }
0faa0fe6f90ea5 Damien Le Moal 2025-01-04  422  

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