git.openwrt.org Git - openwrt/staging/xback.git/blob

   1 From 3cafcfbab9b5f3f1357b415b6ca09911eeb405d6 Mon Sep 17 00:00:00 2001
   2 From: Jonathan Bell <jonathan@raspberrypi.com>
   3 Date: Thu, 4 May 2023 15:48:53 +0100
   4 Subject: [PATCH] drivers: hwmon: rp1-adc: check conversion validity before
   5  supplying value
   6
   7 The SAR ADC architecture may complete a conversion but instability in the
   8 comparator can corrupt the result. Such corruption is signalled in the CS
   9 ERR bit, asserted alongside each conversion result.
  10
  11 Signed-off-by: Jonathan Bell <jonathan@raspberrypi.com>
  12 ---
  13  drivers/hwmon/rp1-adc.c | 10 ++++++++--
  14  1 file changed, 8 insertions(+), 2 deletions(-)
  15
  16 --- a/drivers/hwmon/rp1-adc.c
  17 +++ b/drivers/hwmon/rp1-adc.c
  18 @@ -97,8 +97,14 @@ static int rp1_adc_read(struct rp1_adc_d
  19                data->base + RP1_ADC_RWTYPE_SET + RP1_ADC_CS);
  20
  21         ret = rp1_adc_ready_wait(data);
  22 -       if (!ret)
  23 -               *val = readl(data->base + RP1_ADC_RESULT);
  24 +       if (ret)
  25 +               return ret;
  26 +
  27 +       /* Asserted if the completed conversion had a convergence error */
  28 +       if (readl(data->base + RP1_ADC_CS) & RP1_ADC_CS_ERR)
  29 +               return -EIO;
  30 +
  31 +       *val = readl(data->base + RP1_ADC_RESULT);
  32
  33         spin_unlock(&data->lock);
  34