On Mon, Jul 1, 2019 at 8:44 AM René van Dorst [off-list ref] wrote:

Quoting Willem de Bruijn [off-list ref]:

quoted

On Sat, Jun 29, 2019 at 8:24 AM René van Dorst [off-list ref] wrote:

quoted

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 <redacted>

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

Hi Willem,

Thanks for you input.

This patch was for net-next.

quoted

quoted

---
 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.

You mean in a similar way as done in the ethtool.h [0]?

Use a enum to define the unique bits.

enum mtk_bits {
        MTK_RGMII_BIT = 0,
        MTK_SGMII_BIT,
        MTK_TRGMII_BIT,
        AND SO ON ....
};

Also move the mtk_eth_mux and mtk_eth_path in to this enum.

That's the key part: they are all part of the same namespace and these
enums are not used anywhere else, so a single enum will avoid
accidentally namespace collisions.

Then use defines to convert bits to values.

#define MTK_RGMII  BIT(MTK_RGMII_BIT)
#define MTK_TRGMII BIT(MTK_TRGMII_BIT)

Replace the MTK_PATH_BIT and MTK_PATH_BIT macro with BIT()

Is this what you had in mind?

Great find. Exactly, but I did not find such a clear example.

Greats,

René

[0]:
https://elixir.bootlin.com/linux/latest/source/include/uapi/linux/ethtool.h#L1402