Hi Biju,
Thanks for your patch!
On Thu, 6 Mar 2025 at 13:43, Biju Das <biju.das.jz@xxxxxxxxxxxxxx> wrote:
> R-Car Gen3 and Gen4 has some differences in the shift bits. Add a
have
> shift table to handle these differences. After this drop the unused
> functions reg_gen4() and is_gen4().
>
> Signed-off-by: Biju Das <biju.das.jz@xxxxxxxxxxxxxx>
Reviewed-by: Geert Uytterhoeven <geert+renesas@xxxxxxxxx>
A suggestion for improvement below.
> --- a/drivers/net/can/rcar/rcar_canfd.c
> +++ b/drivers/net/can/rcar/rcar_canfd.c
> @@ -90,11 +90,13 @@
> /* RSCFDnCFDGAFLCFG0 / RSCFDnGAFLCFG0 */
> #define RCANFD_GAFLCFG_SETRNC(gpriv, n, x) \
> (((x) & (gpriv)->info->mask_table[RCANFD_RNC_MASK]) << \
> - (reg_gen4(gpriv, 16, 24) - ((n) & 1) * reg_gen4(gpriv, 16, 8)))
> + ((gpriv)->info->shift_table[RCANFD_FIRST_RNC_SH] - ((n) & 1) * \
> + (gpriv)->info->shift_table[RCANFD_SECOND_RNC_SH]))
Both shifts are dictated by the field width:
- R-Car Gen4 packs 2 values in a 32-bit word, using a field width
of 16 bits,
- R-Car Gen3 packs up to 4 values in a 32-bit word, using a field
width of 8 bits.
The odd split in two shifts is due to the MSB-first numbering of
the fields. Hence I think it would be better to use a field width
parameter, and derive the proper shift value from that (like you have
already done for ICU ;-)
Note that the formula will have to be reworked anyway to support the
third channel on R-Car V3H_2, as "n & "1 will no longer fly here...
> #define RCANFD_GAFLCFG_GETRNC(gpriv, n, x) \
> - (((x) >> (reg_gen4(gpriv, 16, 24) - ((n) & 1) * reg_gen4(gpriv, 16, 8))) & \
> - (gpriv)->info->mask_table[RCANFD_RNC_MASK])
> + (((x) >> ((gpriv)->info->shift_table[RCANFD_FIRST_RNC_SH] - ((n) & 1) * \
> + (gpriv)->info->shift_table[RCANFD_SECOND_RNC_SH])) & \
> + (gpriv)->info->mask_table[RCANFD_RNC_MASK])
Gr{oetje,eeting}s,
Geert
--
Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- geert@xxxxxxxxxxxxxx
In personal conversations with technical people, I call myself a hacker. But
when I'm talking to journalists I just say "programmer" or something like that.
-- Linus Torvalds
