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* [PATCH] spi: tegra20-slink: explicitly enable/disable clock
@ 2018-08-29  6:47 Marcel Ziswiler
  2018-09-03 13:47 ` Applied "spi: tegra20-slink: explicitly enable/disable clock" to the spi tree Mark Brown
  0 siblings, 1 reply; 2+ messages in thread
From: Marcel Ziswiler @ 2018-08-29  6:47 UTC (permalink / raw)
  To: linux-tegra, linux-kernel
  Cc: Marcel Ziswiler, Thierry Reding, Jonathan Hunter, Mark Brown,
	linux-spi, Laxman Dewangan

From: Marcel Ziswiler <marcel.ziswiler@toradex.com>

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>

---

 drivers/spi/spi-tegra20-slink.c | 31 +++++++++++++++++++++++--------
 1 file changed, 23 insertions(+), 8 deletions(-)

diff --git a/drivers/spi/spi-tegra20-slink.c b/drivers/spi/spi-tegra20-slink.c
index 6f7b946b5ced..1427f343b39a 100644
--- 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 @@ static int tegra_slink_probe(struct platform_device *pdev)
 	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);
 
-- 
2.14.4


^ permalink raw reply related	[flat|nested] 2+ messages in thread

end of thread, other threads:[~2018-09-03 13:47 UTC | newest]

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2018-08-29  6:47 [PATCH] spi: tegra20-slink: explicitly enable/disable clock Marcel Ziswiler
2018-09-03 13:47 ` Applied "spi: tegra20-slink: explicitly enable/disable clock" to the spi tree Mark Brown

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