spi: tegra20-slink: explicitly enable/disable clock

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

diff --git a/drivers/spi/spi-tegra20-slink.c b/drivers/spi/spi-tegra20-slink.c
index 6f7b946b5cedf103cbed9886d7ec3079bbdcf6de..1427f343b39a3dc4468e14c3612814508993b3c0 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);