[bug report] spi: spi-qcom-qspi: Add DMA mode support

[Dan Carpenter <dan.carpenter@xxxxxxxxxx>]

Hello Vijaya Krishna Nivarthi,

The patch b5762d95607e: "spi: spi-qcom-qspi: Add DMA mode support"
from Apr 24, 2023, leads to the following Smatch static checker
warning:

	drivers/spi/spi-qcom-qspi.c:368 qcom_qspi_setup_dma_desc()
	warn: sleeping in atomic context

drivers/spi/spi-qcom-qspi.c
    336 static int qcom_qspi_setup_dma_desc(struct qcom_qspi *ctrl,
    337                                 struct spi_transfer *xfer)
    338 {
    339         int ret;
    340         struct sg_table *sgt;
    341         dma_addr_t dma_ptr_sg;
    342         unsigned int dma_len_sg;
    343         int i;
    344 
    345         if (ctrl->n_cmd_desc) {
    346                 dev_err(ctrl->dev, "Remnant dma buffers n_cmd_desc-%d\n", ctrl->n_cmd_desc);
    347                 return -EIO;
    348         }
    349 
    350         sgt = (ctrl->xfer.dir == QSPI_READ) ? &xfer->rx_sg : &xfer->tx_sg;
    351         if (!sgt->nents || sgt->nents > QSPI_MAX_SG) {
    352                 dev_warn_once(ctrl->dev, "Cannot handle %d entries in scatter list\n", sgt->nents);
    353                 return -EAGAIN;
    354         }
    355 
    356         for (i = 0; i < sgt->nents; i++) {
    357                 dma_ptr_sg = sg_dma_address(sgt->sgl + i);
    358                 if (!IS_ALIGNED(dma_ptr_sg, QSPI_ALIGN_REQ)) {
    359                         dev_warn_once(ctrl->dev, "dma_address not aligned to %d\n", QSPI_ALIGN_REQ);
    360                         return -EAGAIN;
    361                 }
    362         }
    363 
    364         for (i = 0; i < sgt->nents; i++) {
    365                 dma_ptr_sg = sg_dma_address(sgt->sgl + i);
    366                 dma_len_sg = sg_dma_len(sgt->sgl + i);
    367 
--> 368                 ret = qcom_qspi_alloc_desc(ctrl, dma_ptr_sg, dma_len_sg);

The qcom_qspi_alloc_desc() is a sleeping allocation, but the caller
qcom_qspi_transfer_one() is holding spin_lock_irqsave(&ctrl->lock, flags).

    369                 if (ret)
    370                         goto cleanup;
    371         }
    372         return 0;
    373 
    374 cleanup:
    375         for (i = 0; i < ctrl->n_cmd_desc; i++)
    376                 dma_pool_free(ctrl->dma_cmd_pool, ctrl->virt_cmd_desc[i],
    377                                   ctrl->dma_cmd_desc[i]);
    378         ctrl->n_cmd_desc = 0;
    379         return ret;
    380 }

regards,
dan carpenter