2019-09-19 14:43:19 +00:00
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From 9f29c6c8865de6f2dc200cb4c59a447d0884a6b3 Mon Sep 17 00:00:00 2001
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2019-08-09 17:50:30 +00:00
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From: Phil Elwell <phil@raspberrypi.org>
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Date: Thu, 1 Aug 2019 08:58:48 +0100
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2019-09-19 14:43:19 +00:00
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Subject: [PATCH 726/806] can: mcp251x: Allow more time after a reset
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2019-08-09 17:50:30 +00:00
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Some boards take longer than 5ms to power up after a reset, so allow
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a few retry attempts before giving up.
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See: https://github.com/raspberrypi/linux/issues/2767
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Signed-off-by: Phil Elwell <phil@raspberrypi.org>
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---
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drivers/net/can/spi/mcp251x.c | 15 ++++++++++++---
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1 file changed, 12 insertions(+), 3 deletions(-)
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--- a/drivers/net/can/spi/mcp251x.c
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+++ b/drivers/net/can/spi/mcp251x.c
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@@ -628,6 +628,7 @@ static int mcp251x_hw_reset(struct spi_d
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struct mcp251x_priv *priv = spi_get_drvdata(spi);
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u8 reg;
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int ret;
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+ int retries = 10;
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/* Wait for oscillator startup timer after power up */
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mdelay(MCP251X_OST_DELAY_MS);
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@@ -637,10 +638,18 @@ static int mcp251x_hw_reset(struct spi_d
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if (ret)
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return ret;
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- /* Wait for oscillator startup timer after reset */
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- mdelay(MCP251X_OST_DELAY_MS);
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+ /*
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+ * Wait for oscillator startup timer after reset
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+ *
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+ * Some devices can take longer than the expected 5ms to wake
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+ * up, so allow a few retries.
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+ */
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+
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+ do {
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+ mdelay(MCP251X_OST_DELAY_MS);
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+ reg = mcp251x_read_reg(spi, CANSTAT);
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+ } while (!reg && retries--);
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- reg = mcp251x_read_reg(spi, CANSTAT);
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if ((reg & CANCTRL_REQOP_MASK) != CANCTRL_REQOP_CONF)
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return -ENODEV;
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