On 1/19/24 09:54, Jiri Slaby wrote:

Hi,

On 19. 01. 24, 10:43, Tudor Ambarus wrote:

quoted

quoted

quoted

If using unsigned int the bitfied is combined with the previous u8
fields, whereas if using u8 the bitfield will be independently defined.
So no benefit in terms of memory footprint, it's just a cosmetic change
to align the bitfield with the previous u8 fields. Allowing u32 for
just
a bit can be misleading as one would ask itself where are the other
bits. Between a u32 bitfield and a bool a u8 bitfield seems like a good
compromise.

Why? What's wrong with bool? bitfields have terrible semantics wrt
atomic writes for example.

Bool occupies a byte and if more port features will ever be added we'll
occupy more bytes. Here's how the structure will look like with a bool:

struct s3c24xx_uart_info {
    const char  *              name;                 /*     0     8 */
    enum s3c24xx_port_type     type;                 /*     8     4 */
    unsigned int               port_type;            /*    12     4 */
    unsigned int               fifosize;             /*    16     4 */
    u32                        rx_fifomask;          /*    20     4 */
    u32                        rx_fifoshift;         /*    24     4 */
    u32                        rx_fifofull;          /*    28     4 */
    u32                        tx_fifomask;          /*    32     4 */
    u32                        tx_fifoshift;         /*    36     4 */
    u32                        tx_fifofull;          /*    40     4 */
    u32                        clksel_mask;          /*    44     4 */
    u32                        clksel_shift;         /*    48     4 */
    u32                        ucon_mask;            /*    52     4 */
    u8                         def_clk_sel;          /*    56     1 */
    u8                         num_clks;             /*    57     1 */
    u8                         iotype;               /*    58     1 */
    bool                       has_divslot;          /*    59     1 */

    /* size: 64, cachelines: 1, members: 17 */
    /* padding: 4 */
};

What's your preference?

bool :).

I'm fine with a bool too as since the introduction of this driver we
have just this flag, it's unlikey to have 4 more soon to bypass the
first cacheline. Will change to bool.

Cheers,
ta

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