Patch "spi: qup: Request DMA before enabling clocks" has been added to the 4.19-stable tree

[Sasha Levin <sashal@xxxxxxxxxx>]

This is a note to let you know that I've just added the patch titled

    spi: qup: Request DMA before enabling clocks

to the 4.19-stable tree which can be found at:
    http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary

The filename of the patch is:
     spi-qup-request-dma-before-enabling-clocks.patch
and it can be found in the queue-4.19 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.



commit b54d289eb7f804f36a4fe76a6f20e1509fd7e85f
Author: Stephan Gerhold <stephan@xxxxxxxxxxx>
Date:   Thu May 18 15:04:25 2023 +0200

    spi: qup: Request DMA before enabling clocks
    
    [ Upstream commit 0c331fd1dccfba657129380ee084b95c1cedfbef ]
    
    It is usually better to request all necessary resources (clocks,
    regulators, ...) before starting to make use of them. That way they do
    not change state in case one of the resources is not available yet and
    probe deferral (-EPROBE_DEFER) is necessary. This is particularly
    important for DMA channels and IOMMUs which are not enforced by
    fw_devlink yet (unless you use fw_devlink.strict=1).
    
    spi-qup does this in the wrong order, the clocks are enabled and
    disabled again when the DMA channels are not available yet.
    
    This causes issues in some cases: On most SoCs one of the SPI QUP
    clocks is shared with the UART controller. When using earlycon UART is
    actively used during boot but might not have probed yet, usually for
    the same reason (waiting for the DMA controller). In this case, the
    brief enable/disable cycle ends up gating the clock and further UART
    console output will halt the system completely.
    
    Avoid this by requesting the DMA channels before changing the clock
    state.
    
    Fixes: 612762e82ae6 ("spi: qup: Add DMA capabilities")
    Signed-off-by: Stephan Gerhold <stephan@xxxxxxxxxxx>
    Link: https://lore.kernel.org/r/20230518-spi-qup-clk-defer-v1-1-f49fc9ca4e02@xxxxxxxxxxx
    Signed-off-by: Mark Brown <broonie@xxxxxxxxxx>
    Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>

diff --git a/drivers/spi/spi-qup.c b/drivers/spi/spi-qup.c
index defe959884dae..1518a8bf49be1 100644
--- a/drivers/spi/spi-qup.c
+++ b/drivers/spi/spi-qup.c
@@ -1003,23 +1003,8 @@ static int spi_qup_probe(struct platform_device *pdev)
 		return -ENXIO;
 	}
 
-	ret = clk_prepare_enable(cclk);
-	if (ret) {
-		dev_err(dev, "cannot enable core clock\n");
-		return ret;
-	}
-
-	ret = clk_prepare_enable(iclk);
-	if (ret) {
-		clk_disable_unprepare(cclk);
-		dev_err(dev, "cannot enable iface clock\n");
-		return ret;
-	}
-
 	master = spi_alloc_master(dev, sizeof(struct spi_qup));
 	if (!master) {
-		clk_disable_unprepare(cclk);
-		clk_disable_unprepare(iclk);
 		dev_err(dev, "cannot allocate master\n");
 		return -ENOMEM;
 	}
@@ -1065,6 +1050,19 @@ static int spi_qup_probe(struct platform_device *pdev)
 	spin_lock_init(&controller->lock);
 	init_completion(&controller->done);
 
+	ret = clk_prepare_enable(cclk);
+	if (ret) {
+		dev_err(dev, "cannot enable core clock\n");
+		goto error_dma;
+	}
+
+	ret = clk_prepare_enable(iclk);
+	if (ret) {
+		clk_disable_unprepare(cclk);
+		dev_err(dev, "cannot enable iface clock\n");
+		goto error_dma;
+	}
+
 	iomode = readl_relaxed(base + QUP_IO_M_MODES);
 
 	size = QUP_IO_M_OUTPUT_BLOCK_SIZE(iomode);
@@ -1094,7 +1092,7 @@ static int spi_qup_probe(struct platform_device *pdev)
 	ret = spi_qup_set_state(controller, QUP_STATE_RESET);
 	if (ret) {
 		dev_err(dev, "cannot set RESET state\n");
-		goto error_dma;
+		goto error_clk;
 	}
 
 	writel_relaxed(0, base + QUP_OPERATIONAL);
@@ -1118,7 +1116,7 @@ static int spi_qup_probe(struct platform_device *pdev)
 	ret = devm_request_irq(dev, irq, spi_qup_qup_irq,
 			       IRQF_TRIGGER_HIGH, pdev->name, controller);
 	if (ret)
-		goto error_dma;
+		goto error_clk;
 
 	pm_runtime_set_autosuspend_delay(dev, MSEC_PER_SEC);
 	pm_runtime_use_autosuspend(dev);
@@ -1133,11 +1131,12 @@ static int spi_qup_probe(struct platform_device *pdev)
 
 disable_pm:
 	pm_runtime_disable(&pdev->dev);
+error_clk:
+	clk_disable_unprepare(cclk);
+	clk_disable_unprepare(iclk);
 error_dma:
 	spi_qup_release_dma(master);
 error:
-	clk_disable_unprepare(cclk);
-	clk_disable_unprepare(iclk);
 	spi_master_put(master);
 	return ret;
 }