1. 16 12月, 2016 1 次提交
    • T
      ASoC: hdmi-codec: use unsigned type to structure members with bit-field · 9e4d59ad
      Takashi Sakamoto 提交于
      This is a fix for Linux 4.10-rc1.
      
      In C language specification, a bit-field is interpreted as a signed or
      unsigned integer type consisting of the specified number of bits.
      
      In GCC manual, the range of a signed bit field of N bits is from
      -(2^N) / 2 to ((2^N) / 2) - 1
      https://www.gnu.org/software/gnu-c-manual/gnu-c-manual.html#Bit-Fields
      
      Therefore, when defined as 1 bit-field with signed type, variables can
      represents -1 and 0.
      
      The snd-soc-hdmi-codec module includes a structure which has signed type
      members with bit-fields. Codes of this module assign 0 and 1 to the
      members. This seems to result in implementation-dependent behaviours.
      
      As of v4.10-rc1 merge window, outside of sound subsystem, this structure
      is referred by below GPU modules.
       - tda998x
       - sti-drm
       - mediatek-drm-hdmi
       - msm
      
      As long as I review their codes relevant to the structure, the structure
      members are used just for condition statements and printk formats.
      My proposal of change is a bit intrusive to the printk formats but this
      may be acceptable.
      
      Totally, it's reasonable to use unsigned type for the structure members.
      This bug is detected by Sparse, static code analyzer with below warnings.
      
      ./include/sound/hdmi-codec.h:39:26: error: dubious one-bit signed bitfield
      ./include/sound/hdmi-codec.h:40:28: error: dubious one-bit signed bitfield
      ./include/sound/hdmi-codec.h:41:29: error: dubious one-bit signed bitfield
      ./include/sound/hdmi-codec.h:42:31: error: dubious one-bit signed bitfield
      
      Fixes: 09184118 ("ASoC: hdmi-codec: Add hdmi-codec for external HDMI-encoders")
      Signed-off-by: NTakashi Sakamoto <o-takashi@sakamocchi.jp>
      Acked-by: NArnaud Pouliquen <arnaud.pouliquen@st.com>
      Signed-off-by: NMark Brown <broonie@kernel.org>
      CC: stable@vger.kernel.org
      9e4d59ad
  2. 12 12月, 2016 27 次提交
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