dmaengine: stm32-dma: driver defers probe for reset

Change STM32 DMA driver to defer its probe operation when reset
controller is expected but has not been probed yet when DMA
device is probed.

Changes error traces when failing to get a system resource so that
it is not printed on failure with deferred probing.

Signed-off-by: Etienne Carriere <etienne.carriere@st.com>
Signed-off-by: Amelie Delaunay <amelie.delaunay@st.com>
Link: https://lore.kernel.org/r/20200129153628.29329-4-amelie.delaunay@st.com
Signed-off-by: Vinod Koul <vkoul@kernel.org>

diff --git a/drivers/dma/stm32-dma.c b/drivers/dma/stm32-dma.c
index e31414796ec4e13dbe578bda037cece29e746cf7..c8bbe08b8e32630b813589b97e37dffb7702c924 100644 (file)
--- a/drivers/dma/stm32-dma.c
+++ b/drivers/dma/stm32-dma.c
@@ -1296,8 +1296,10 @@ static int stm32_dma_probe(struct platform_device *pdev)
 
        dmadev->clk = devm_clk_get(&pdev->dev, NULL);
        if (IS_ERR(dmadev->clk)) {
-               dev_err(&pdev->dev, "Error: Missing controller clock\n");
-               return PTR_ERR(dmadev->clk);
+               ret = PTR_ERR(dmadev->clk);
+               if (ret != -EPROBE_DEFER)
+                       dev_err(&pdev->dev, "Can't get clock\n");
+               return ret;
        }
 
        ret = clk_prepare_enable(dmadev->clk);
@@ -1310,7 +1312,11 @@ static int stm32_dma_probe(struct platform_device *pdev)
                                                "st,mem2mem");
 
        rst = devm_reset_control_get(&pdev->dev, NULL);
-       if (!IS_ERR(rst)) {
+       if (IS_ERR(rst)) {
+               ret = PTR_ERR(rst);
+               if (ret == -EPROBE_DEFER)
+                       goto clk_free;
+       } else {
                reset_control_assert(rst);
                udelay(2);
                reset_control_deassert(rst);
@@ -1470,10 +1476,11 @@ static struct platform_driver stm32_dma_driver = {
                .of_match_table = stm32_dma_of_match,
                .pm = &stm32_dma_pm_ops,
        },
+       .probe = stm32_dma_probe,
 };
 
 static int __init stm32_dma_init(void)
 {
-       return platform_driver_probe(&stm32_dma_driver, stm32_dma_probe);
+       return platform_driver_register(&stm32_dma_driver);
 }
 subsys_initcall(stm32_dma_init);