Re: [PATCH] soc/tegra: fuse: Fix bitwise vs. logical OR warning

From: Michał Mirosław
Date: Thu Oct 21 2021 - 17:55:40 EST


On Thu, Oct 21, 2021 at 02:45:00PM -0700, Nathan Chancellor wrote:
[...]
> --- a/drivers/soc/tegra/fuse/speedo-tegra20.c
> +++ b/drivers/soc/tegra/fuse/speedo-tegra20.c
> @@ -69,7 +69,7 @@ void __init tegra20_init_speedo_data(struct tegra_sku_info *sku_info)
>
> val = 0;
> for (i = CPU_SPEEDO_MSBIT; i >= CPU_SPEEDO_LSBIT; i--) {
> - reg = tegra_fuse_read_spare(i) |
> + reg = tegra_fuse_read_spare(i) ||
> tegra_fuse_read_spare(i + CPU_SPEEDO_REDUND_OFFS);
> val = (val << 1) | (reg & 0x1);
> }
> @@ -84,7 +84,7 @@ void __init tegra20_init_speedo_data(struct tegra_sku_info *sku_info)
>
> val = 0;
> for (i = SOC_SPEEDO_MSBIT; i >= SOC_SPEEDO_LSBIT; i--) {
> - reg = tegra_fuse_read_spare(i) |
> + reg = tegra_fuse_read_spare(i) ||
> tegra_fuse_read_spare(i + SOC_SPEEDO_REDUND_OFFS);
> val = (val << 1) | (reg & 0x1);
> }

It does seem correct, but nevertheless the code looks suspicious. reg is
already masked with 0x1 as far as I can tell, and there are other places
which depend on this (like speedo-tegra210.c). Guessing from the use of
tegra_fuse_read_spare() I would recommend changing its return type as it
is returing a bit value, not necessarily semantically a boolean.

Best Regards
Michał Mirosław