spi: tegra20-slink: explicitly enable/disable clock

BugLink: https://bugs.launchpad.net/bugs/1836287
commit 7001cab1dabc0b72b2b672ef58a90ab64f5e2343 upstream.

Depending on the SPI instance one may get an interrupt storm upon
requesting resp. interrupt unless the clock is explicitly enabled
beforehand. This has been observed trying to bring up instance 4 on
T20.

Signed-off-by: Marcel Ziswiler <marcel.ziswiler@toradex.com>
Signed-off-by: Mark Brown <broonie@kernel.org>
Cc: stable@vger.kernel.org
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Kamal Mostafa <kamal@canonical.com>
Signed-off-by: Khalid Elmously <khalid.elmously@canonical.com>

diff --git a/drivers/spi/spi-tegra20-slink.c b/drivers/spi/spi-tegra20-slink.c
index 3e12d5f87ee4412b086649c8f2312fb3cc9e30a8..9831c1106945e835d6f8891569a8adc9bbcdc42a 100644 (file)
--- a/drivers/spi/spi-tegra20-slink.c
+++ b/drivers/spi/spi-tegra20-slink.c
@@ -1063,6 +1063,24 @@ static int tegra_slink_probe(struct platform_device *pdev)
                goto exit_free_master;
        }
 
+       /* disabled clock may cause interrupt storm upon request */
+       tspi->clk = devm_clk_get(&pdev->dev, NULL);
+       if (IS_ERR(tspi->clk)) {
+               ret = PTR_ERR(tspi->clk);
+               dev_err(&pdev->dev, "Can not get clock %d\n", ret);
+               goto exit_free_master;
+       }
+       ret = clk_prepare(tspi->clk);
+       if (ret < 0) {
+               dev_err(&pdev->dev, "Clock prepare failed %d\n", ret);
+               goto exit_free_master;
+       }
+       ret = clk_enable(tspi->clk);
+       if (ret < 0) {
+               dev_err(&pdev->dev, "Clock enable failed %d\n", ret);
+               goto exit_free_master;
+       }
+
        spi_irq = platform_get_irq(pdev, 0);
        tspi->irq = spi_irq;
        ret = request_threaded_irq(tspi->irq, tegra_slink_isr,
@@ -1071,14 +1089,7 @@ static int tegra_slink_probe(struct platform_device *pdev)
        if (ret < 0) {
                dev_err(&pdev->dev, "Failed to register ISR for IRQ %d\n",
                                        tspi->irq);
-               goto exit_free_master;
-       }
-
-       tspi->clk = devm_clk_get(&pdev->dev, NULL);
-       if (IS_ERR(tspi->clk)) {
-               dev_err(&pdev->dev, "can not get clock\n");
-               ret = PTR_ERR(tspi->clk);
-               goto exit_free_irq;
+               goto exit_clk_disable;
        }
 
        tspi->rst = devm_reset_control_get_exclusive(&pdev->dev, "spi");
@@ -1138,6 +1149,8 @@ exit_rx_dma_free:
        tegra_slink_deinit_dma_param(tspi, true);
 exit_free_irq:
        free_irq(spi_irq, tspi);
+exit_clk_disable:
+       clk_disable(tspi->clk);
 exit_free_master:
        spi_master_put(master);
        return ret;
@@ -1150,6 +1163,8 @@ static int tegra_slink_remove(struct platform_device *pdev)
 
        free_irq(tspi->irq, tspi);
 
+       clk_disable(tspi->clk);
+
        if (tspi->tx_dma_chan)
                tegra_slink_deinit_dma_param(tspi, false);