target/linux/brcm2708/patches-4.19/950-0727-can-mcp251x-Allow-more-time-after-a-reset.patch

   1 From 0bcf10eaed142257cbac31a6bcf18de03379fe38 Mon Sep 17 00:00:00 2001
   2 From: Phil Elwell <phil@raspberrypi.org>
   3 Date: Thu, 1 Aug 2019 08:58:48 +0100
   4 Subject: [PATCH 727/773] can: mcp251x: Allow more time after a reset
   5
   6 Some boards take longer than 5ms to power up after a reset, so allow
   7 a few retry attempts before giving up.
   8
   9 See: https://github.com/raspberrypi/linux/issues/2767
  10
  11 Signed-off-by: Phil Elwell <phil@raspberrypi.org>
  12 ---
  13  drivers/net/can/spi/mcp251x.c | 15 ++++++++++++---
  14  1 file changed, 12 insertions(+), 3 deletions(-)
  15
  16 --- a/drivers/net/can/spi/mcp251x.c
  17 +++ b/drivers/net/can/spi/mcp251x.c
  18 @@ -628,6 +628,7 @@ static int mcp251x_hw_reset(struct spi_d
  19         struct mcp251x_priv *priv = spi_get_drvdata(spi);
  20         u8 reg;
  21         int ret;
  22 +       int retries = 10;
  23
  24         /* Wait for oscillator startup timer after power up */
  25         mdelay(MCP251X_OST_DELAY_MS);
  26 @@ -637,10 +638,18 @@ static int mcp251x_hw_reset(struct spi_d
  27         if (ret)
  28                 return ret;
  29
  30 -       /* Wait for oscillator startup timer after reset */
  31 -       mdelay(MCP251X_OST_DELAY_MS);
  32 +       /*
  33 +        * Wait for oscillator startup timer after reset
  34 +        *
  35 +        * Some devices can take longer than the expected 5ms to wake
  36 +        * up, so allow a few retries.
  37 +        */
  38 +
  39 +       do {
  40 +               mdelay(MCP251X_OST_DELAY_MS);
  41 +               reg = mcp251x_read_reg(spi, CANSTAT);
  42 +       } while (!reg && retries--);
  43
  44 -       reg = mcp251x_read_reg(spi, CANSTAT);
  45         if ((reg & CANCTRL_REQOP_MASK) != CANCTRL_REQOP_CONF)
  46                 return -ENODEV;
  47