On Wed, Jul 04, 2018 at 08:33:20PM +0200, Linus Walleij wrote:
> The code to calculate the hardware register enumerator
> for the maximum L3 length isn't entirely simple to read.
> Use the existing defines and rewrite the function into a
> table look-up.
A matter of habit. ;-)
I think that if you just renamed 'n' to 'best_index' and avoided
reusing 'max_l3_len' (as you already did) the idea could be made
more obvious without expading the code to twice the lines.
The max_len[] array in the original code documents how the HW reacts
to a specific setting.
Acked-by: Michał Mirosław <mirq-li...@rere.qmqm.pl>
Best Regards,
Michał Mirosław
>
> Signed-off-by: Linus Walleij <linus.wall...@linaro.org>
> ---
> ChangeLog v1->v2:
> - No changes, just resending with the rest.
> ---
> drivers/net/ethernet/cortina/gemini.c | 61 ++++++++++++++++++++-------
> 1 file changed, 46 insertions(+), 15 deletions(-)
>
> diff --git a/drivers/net/ethernet/cortina/gemini.c
> b/drivers/net/ethernet/cortina/gemini.c
> index 6d7404f66f84..8fc31723f700 100644
> --- a/drivers/net/ethernet/cortina/gemini.c
> +++ b/drivers/net/ethernet/cortina/gemini.c
> @@ -401,26 +401,57 @@ static int gmac_setup_phy(struct net_device *netdev)
> return 0;
> }
>
> -static int gmac_pick_rx_max_len(int max_l3_len)
> -{
> - /* index = CONFIG_MAXLEN_XXX values */
> - static const int max_len[8] = {
> - 1536, 1518, 1522, 1542,
> - 9212, 10236, 1518, 1518
> - };
> - int i, n = 5;
> +/* The maximum frame length is not logically enumerated in the
> + * hardware, so we do a table lookup to find the applicable max
> + * frame length.
> + */
> +struct gmac_max_framelen {
> + unsigned int max_l3_len;
> + u8 val;
> +};
>
> - max_l3_len += ETH_HLEN + VLAN_HLEN;
> +static const struct gmac_max_framelen gmac_maxlens[] = {
> + {
> + .max_l3_len = 1518,
> + .val = CONFIG0_MAXLEN_1518,
> + },
> + {
> + .max_l3_len = 1522,
> + .val = CONFIG0_MAXLEN_1522,
> + },
> + {
> + .max_l3_len = 1536,
> + .val = CONFIG0_MAXLEN_1536,
> + },
> + {
> + .max_l3_len = 1542,
> + .val = CONFIG0_MAXLEN_1542,
> + },
> + {
> + .max_l3_len = 9212,
> + .val = CONFIG0_MAXLEN_9k,
> + },
> + {
> + .max_l3_len = 10236,
> + .val = CONFIG0_MAXLEN_10k,
> + },
> +};
> +
> +static int gmac_pick_rx_max_len(unsigned int max_l3_len)
> +{
> + const struct gmac_max_framelen *maxlen;
> + int maxtot;
> + int i;
>
> - if (max_l3_len > max_len[n])
> - return -1;
> + maxtot = max_l3_len + ETH_HLEN + VLAN_HLEN;
>
> - for (i = 0; i < 5; i++) {
> - if (max_len[i] >= max_l3_len && max_len[i] < max_len[n])
> - n = i;
> + for (i = 0; i < ARRAY_SIZE(gmac_maxlens); i++) {
> + maxlen = &gmac_maxlens[i];
> + if (maxtot <= maxlen->max_l3_len)
> + return maxlen->val;
> }
>
> - return n;
> + return -1;
> }
>
> static int gmac_init(struct net_device *netdev)
> --
> 2.17.1
>
