[bug report] ASoC: tegra: Add Tegra210 based OPE driver

[Sameer Pujar]

On 14-06-2022 11:39, Dan Carpenter wrote:
>>> Hello Sameer Pujar,
>>>
>>> The patch 7358a803c778: "ASoC: tegra: Add Tegra210 based OPE driver"
>>> from Jun 3, 2022, leads to the following Smatch static checker
>>> warning:
>>>
>>>           sound/soc/tegra/tegra210_mbdrc.c:778 tegra210_mbdrc_hw_params()
>>>           warn: bitwise AND condition is false here
>>>
>>> sound/soc/tegra/tegra210_mbdrc.c
>>>       769 int tegra210_mbdrc_hw_params(struct snd_soc_component *cmpnt)
>>>       770 {
>>>       771         struct tegra210_ope *ope = snd_soc_component_get_drvdata(cmpnt);
>>>       772         const struct tegra210_mbdrc_config *conf = &mbdrc_init_config;
>>>       773         u32 val = 0;
>>>       774         unsigned int i;
>>>       775
>>>       776         regmap_read(ope->mbdrc_regmap, TEGRA210_MBDRC_CFG, &val);
>>>       777
>>> --> 778         if (val & TEGRA210_MBDRC_CFG_MBDRC_MODE_BYPASS)
>>>                             ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
>>>
>>> TEGRA210_MBDRC_CFG_MBDRC_MODE_BYPASS is zero so this can't be true.
>>>
>>> #define TEGRA210_MBDRC_CFG_MBDRC_MODE_BYPASS            (0 << TEGRA210_MBDRC_CFG_MBDRC_MODE_SHIFT)
>>>
>>> The common false positive with this warning is that the macro is
>>> something which depends on the .config and in that case I just add it
>>> to the list in smatch_data/kernel.unconstant_macros.  But in this case
>>> the macro is just always zero...  Is there a plan to make it
>>> configurable or something?
>> Thanks Dan for reporting this. The device is actually configurable. I will
>> provide a patch to fix above condition.
> What I meant by configurable is:
>
> #ifdef CONFIG_FOO
> #define MASK 0x30
> #else
> #define MASK 0
> #endif
>
> Smatch works on the preprocessed source so it doesn't see that there
> are two definitions of MASK.

By configurable I meant, the device (OPE in this case) supports 
different configurations driven by user space control settings. Above if 
condition (val & TEGRA210_MBDRC_CFG_MBDRC_MODE_BYPASS) is wrong, instead 
proper mask needs to be used. I have sent a patch to fix this now.