netdev - Re: [PATCH] net: ethernet: mediatek: Fix overlapping capability bits.

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Date:   Sat, 29 Jun 2019 15:33:57 -0400
From:   Willem de Bruijn <willemdebruijn.kernel@...il.com>
To:     René van Dorst <opensource@...rst.com>
Cc:     sean.wang@...iatek.com, f.fainelli@...il.com,
        linux@...linux.org.uk, David Miller <davem@...emloft.net>,
        matthias.bgg@...il.com, andrew@...n.ch, vivien.didelot@...il.com,
        frank-w@...lic-files.de,
        Network Development <netdev@...r.kernel.org>,
        linux-mediatek@...ts.infradead.org, linux-mips@...r.kernel.org
Subject: Re: [PATCH] net: ethernet: mediatek: Fix overlapping capability bits.

On Sat, Jun 29, 2019 at 8:24 AM René van Dorst <opensource@...rst.com> wrote:
>
> Both MTK_TRGMII_MT7621_CLK and MTK_PATH_BIT are defined as bit 10.
>
> This causes issues on non-MT7621 devices which has the
> MTK_PATH_BIT(MTK_ETH_PATH_GMAC1_RGMII) capability set.
> The wrong TRGMII setup code is executed.
>
> Moving the MTK_PATH_BIT to bit 11 fixes the issue.
>
> Fixes: 8efaa653a8a5 ("net: ethernet: mediatek: Add MT7621 TRGMII mode
> support")
> Signed-off-by: René van Dorst <opensource@...rst.com>

This targets net? Please mark networking patches [PATCH net] or [PATCH
net-next].

> ---
>  drivers/net/ethernet/mediatek/mtk_eth_soc.h | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/drivers/net/ethernet/mediatek/mtk_eth_soc.h b/drivers/net/ethernet/mediatek/mtk_eth_soc.h
> index 876ce6798709..2cb8a915731c 100644
> --- a/drivers/net/ethernet/mediatek/mtk_eth_soc.h
> +++ b/drivers/net/ethernet/mediatek/mtk_eth_soc.h
> @@ -626,7 +626,7 @@ enum mtk_eth_path {
>  #define MTK_TRGMII_MT7621_CLK          BIT(10)
>
>  /* Supported path present on SoCs */
> -#define MTK_PATH_BIT(x)         BIT((x) + 10)
>
> +#define MTK_PATH_BIT(x)         BIT((x) + 11)
>

To avoid this happening again, perhaps make the reserved range more explicit?

For instance

#define MTK_FIXED_BIT_LAST 10
#define MTK_TRGMII_MT7621_CLK  BIT(MTK_FIXED_BIT_LAST)

#define MTK_PATH_BIT_FIRST  (MTK_FIXED_BIT_LAST + 1)
#define MTK_PATH_BIT_LAST (MTK_FIXED_BIT_LAST + 7)
#define MTK_MUX_BIT_FIRST (MTK_PATH_BIT_LAST + 1)

Though I imagine there are cleaner approaches. Perhaps define all
fields as enum instead of just mtk_eth_mux and mtk_eth_path. Then
there can be no accidental collision.