17.05.2021 17:04, Krzysztof Kozlowski пишет: > On 17/05/2021 09:47, Dmitry Osipenko wrote: >> 17.05.2021 16:39, Krzysztof Kozlowski пишет: >>>>>> #define DRAM_DEV_SEL_ALL 0 >>>>>> -#define DRAM_DEV_SEL_0 (2 << 30) >>>>>> -#define DRAM_DEV_SEL_1 (1 << 30) >>>>>> +#define DRAM_DEV_SEL_0 (2u << 30) >>>>>> +#define DRAM_DEV_SEL_1 (1u << 30) >>>>> >>>>> Why not using BIT()? This would make even this 2<<30 less awkard... >>>> >>>> The bitfield 31:30 is a enum, 3 is a wrong value. Formally it's >>>> incorrect to use the BIT() macro here. >>> >>> Why "3"? BIT(31) is the same as 2<<30. >> >> By 3 I meant BIT(31)|BIT(30). This bitfield is explicitly designated as >> a enum in the hardware documentation. > > I understand it and using BIT() here does not mean someone has to set > both of them. BIT() is a helper pointing out that you want to toggle one > bit. It does not mean that it is allowed to do so always! > >> >>> It's common to use BIT for >>> register fields which do not accept all possible values. Now you >>> basically reimplement BIT() which is error-prone. >> >> Could you please show couple examples? The common practice today is to >> use FIELD_PREP helpers, but this driver was written before these helpers >> existed. > > > There are plenty of such examples so I guess it would be easier to ask > you to provide counter ones. Few IT for enum-like registers found within 2 minutes: > > https://elixir.bootlin.com/linux/latest/C/ident/MAX77620_CNFG_GPIO_INT_MASK > https://elixir.bootlin.com/linux/v5.13-rc2/source/drivers/regulator/max77650-regulator.c#L18 > https://elixir.bootlin.com/linux/v5.13-rc2/source/drivers/regulator/tps6524x-regulator.c#L62 > https://elixir.bootlin.com/linux/v5.13-rc2/source/drivers/regulator/tps80031-regulator.c#L39 > https://elixir.bootlin.com/linux/v5.13-rc2/source/drivers/regulator/da9121-regulator.h#L200 > https://elixir.bootlin.com/linux/v5.13-rc2/source/drivers/regulator/da9121-regulator.h#L231 Alright, I'll use the BIT macro in the v3. I also realized now that the tegra30-emc drivers needs the same change. Thank you for the review.
