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.
