[PATCH v3 0/9] backlight: qcom-wled: fix and solidify handling of enabled-strings

[Marijn Suijten]

This patchset fixes WLED's handling of enabled-strings: besides some
cleanup it is now actually possible to specify a non-contiguous array of
enabled strings (not necessarily starting at zero) and the values from
DT are now validated to prevent possible unexpected out-of-bounds
register and array element accesses.
Off-by-one mistakes in the maximum number of strings, also causing
out-of-bounds access, have been addressed as well.

Changes in v3:
- Use __le16 type for cpu_to_le16 result;
- Reword ambiguity warning between qcom,num-strings and
  qcom,enabled-strings to explain that only one should/needs to be set;
- Move this warning from patch 4 patch 5, where the length of
  qcom,enabled-strings starts to be taken into account;
- Drop DT patches that have been picked up in the qcom tree.

v2: https://lore.kernel.org/lkml/20211112002706.453289-1-marijn.suijten@somainline.org/T

Changes in v2:
- Reordered patch 4/10 (Validate enabled string indices in DT) to sit
  before patch 1/10 (Pass number of elements to read to read_u32_array);
- Pulled qcom,num-strings out of the DT enumeration parser, and moved it
  after qcom,enabled-strings parser to always have final sign-off over
  the number of strings;
- Extra validation for this number of strings against
  qcom,enabled-strings;
- Recombined patch 9 (Consistently use enabled-strings in
  set_brightness) and patch 10 (Consider enabled_strings in
  autodetection), which both solve the same problem in two different
  functions.  In addition the autodetection code uses set_brightness as
  helper already;
- Improved DT configurations for pmi8994 and pm660l, currently in 5.15
  rc's.

v1: https://lore.kernel.org/dri-devel/20211004192741.621870-1-marijn.suijten@somainline.org/T

Marijn Suijten (9):
  backlight: qcom-wled: Validate enabled string indices in DT
  backlight: qcom-wled: Pass number of elements to read to
    read_u32_array
  backlight: qcom-wled: Use cpu_to_le16 macro to perform conversion
  backlight: qcom-wled: Fix off-by-one maximum with default num_strings
  backlight: qcom-wled: Override default length with
    qcom,enabled-strings
  backlight: qcom-wled: Remove unnecessary 4th default string in WLED3
  backlight: qcom-wled: Provide enabled_strings default for WLED 4 and 5
  backlight: qcom-wled: Remove unnecessary double whitespace
  backlight: qcom-wled: Respect enabled-strings in set_brightness

 drivers/video/backlight/qcom-wled.c | 130 +++++++++++++++-------------
 1 file changed, 72 insertions(+), 58 deletions(-)


base-commit: fa55b7dcdc43c1aa1ba12bca9d2dd4318c2a0dbf
--
2.33.1