mtd: spi-nor: cadence-quadspi: Handle probe deferral while requesting DMA channel

[ Upstream commit 6ae9bf23828d11ed7bedb4aa1e25747fd93b3369 ]

dma_request_chan_by_mask() can throw EPROBE_DEFER if DMA provider
is not yet probed. Currently driver just falls back to using PIO mode
(which is less efficient) in this case. Instead return probe deferral
error as is so that driver will be re probed once DMA provider is
available.

Signed-off-by: Vignesh Raghavendra <vigneshr@ti.com>
Reviewed-by: Tudor Ambarus <tudor.ambarus@microchip.com>
Acked-by: Tudor Ambarus <tudor.ambarus@microchip.com>
Link: https://lore.kernel.org/r/20200601070444.16923-6-vigneshr@ti.com
Signed-off-by: Mark Brown <broonie@kernel.org>
Stable-dep-of: 2087e85bb66e ("spi: cadence-quadspi: fix suspend-resume implementations")
Signed-off-by: Sasha Levin <sashal@kernel.org>

diff --git a/drivers/mtd/spi-nor/cadence-quadspi.c b/drivers/mtd/spi-nor/cadence-quadspi.c
index ad27d3e4c5dbc86692c4dbea509c07de6873f02b..2c5a6587f505e0de01e2519e61880461fc9e568f 100644 (file)
--- a/drivers/mtd/spi-nor/cadence-quadspi.c
+++ b/drivers/mtd/spi-nor/cadence-quadspi.c
@@ -1168,7 +1168,7 @@ static void cqspi_controller_init(struct cqspi_st *cqspi)
        cqspi_controller_enable(cqspi, 1);
 }
 
-static void cqspi_request_mmap_dma(struct cqspi_st *cqspi)
+static int cqspi_request_mmap_dma(struct cqspi_st *cqspi)
 {
        dma_cap_mask_t mask;
 
@@ -1177,11 +1177,16 @@ static void cqspi_request_mmap_dma(struct cqspi_st *cqspi)
 
        cqspi->rx_chan = dma_request_chan_by_mask(&mask);
        if (IS_ERR(cqspi->rx_chan)) {
-               dev_err(&cqspi->pdev->dev, "No Rx DMA available\n");
+               int ret = PTR_ERR(cqspi->rx_chan);
+
+               if (ret != -EPROBE_DEFER)
+                       dev_err(&cqspi->pdev->dev, "No Rx DMA available\n");
                cqspi->rx_chan = NULL;
-               return;
+               return ret;
        }
        init_completion(&cqspi->rx_dma_complete);
+
+       return 0;
 }
 
 static int cqspi_setup_flash(struct cqspi_st *cqspi, struct device_node *np)
@@ -1265,8 +1270,11 @@ static int cqspi_setup_flash(struct cqspi_st *cqspi, struct device_node *np)
                        dev_dbg(nor->dev, "using direct mode for %s\n",
                                mtd->name);
 
-                       if (!cqspi->rx_chan)
-                               cqspi_request_mmap_dma(cqspi);
+                       if (!cqspi->rx_chan) {
+                               ret = cqspi_request_mmap_dma(cqspi);
+                               if (ret == -EPROBE_DEFER)
+                                       goto err;
+                       }
                }
        }