Messages in this thread | | | Subject | Re: [PATCH v2 3/9] soc: samsung: Add Exynos Adaptive Supply Voltage driver | From | Robin Murphy <> | Date | Thu, 8 Aug 2019 13:48:24 +0100 |
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On 08/08/2019 13:31, Krzysztof Kozlowski wrote: > On Thu, 8 Aug 2019 at 14:07, Sylwester Nawrocki <s.nawrocki@samsung.com> wrote: >>>> +static unsigned int exynos5422_asv_parse_table(struct exynos_asv *asv, >>>> + unsigned int pkg_id) >>>> +{ >>>> + return (pkg_id >> EXYNOS5422_TABLE_OFFSET) & EXYNOS5422_TABLE_MASK; >>>> +} >>>> + >>>> +static bool exynos5422_asv_parse_bin2(struct exynos_asv *asv, >>>> + unsigned int pkg_id) >>>> +{ >>>> + return (pkg_id >> EXYNOS5422_BIN2_OFFSET) & EXYNOS5422_BIN2_MASK; >>> >>> return !!() for converting to boolean. >> >> I'm not convinced it is needed, the return type of the function is bool >> and value of the expression will be implicitly converted to that type. >> Is there any compiler warning related to that? > > Yeah, but bool is int so there will be no implicit conversion... I > guess it is a convention. In theory !! is the proper conversion to > bool but if bool==int then it's essentially conversion to 1. I am not > sure what's the benefit, maybe for some wrong code which would do > comparisons on result like if (exynos5422_asv_parse_bin2() == TRUE)...
Not so - since we use "-std=gnu89", we have C99-like _Bool, which our bool is a typedef of. Conversions, either implicit or explicit, are well-defined:
"6.3.1.2 Boolean type
When any scalar value is converted to _Bool, the result is 0 if the value compares equal to 0; otherwise, the result is 1."
This is even called out in Documentation/process/coding-style.rst:
"When using bool types the !! construction is not needed, which eliminates a class of bugs."
Robin.
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