2022-03-31 22:11:58

by Chen-Yu Tsai

Subject: [PATCH] net: stmmac: Fix unset max_speed difference between DT and non-DT platforms

From: Chen-Yu Tsai <[email protected]>

In commit 9cbadf094d9d ("net: stmmac: support max-speed device tree
property"), when DT platforms don't set "max-speed", max_speed is set to
-1; for non-DT platforms, it stays the default 0.

Prior to commit eeef2f6b9f6e ("net: stmmac: Start adding phylink support"),
the check for a valid max_speed setting was to check if it was greater
than zero. This commit got it right, but subsequent patches just checked
for non-zero, which is incorrect for DT platforms.

In commit 92c3807b9ac3 ("net: stmmac: convert to phylink_get_linkmodes()")
the conversion switched completely to checking for non-zero value as a
valid value, which caused 1000base-T to stop getting advertised by
default.

Instead of trying to fix all the checks, simply leave max_speed alone if
DT property parsing fails.

Fixes: 9cbadf094d9d ("net: stmmac: support max-speed device tree property")
Fixes: 92c3807b9ac3 ("net: stmmac: convert to phylink_get_linkmodes()")
Signed-off-by: Chen-Yu Tsai <[email protected]>
---

This was first noticed on ROC-RK3399-PC, and also observed on ROC-RK3328-CC.
The fix was tested on ROC-RK3328-CC and Libre Computer ALL-H5-ALL-CC.

drivers/net/ethernet/stmicro/stmmac/stmmac_platform.c | 3 +--
1 file changed, 1 insertion(+), 2 deletions(-)

diff --git a/drivers/net/ethernet/stmicro/stmmac/stmmac_platform.c b/drivers/net/ethernet/stmicro/stmmac/stmmac_platform.c
index 5d29f336315b..11e1055e8260 100644
--- a/drivers/net/ethernet/stmicro/stmmac/stmmac_platform.c
+++ b/drivers/net/ethernet/stmicro/stmmac/stmmac_platform.c
@@ -431,8 +431,7 @@ stmmac_probe_config_dt(struct platform_device *pdev, u8 *mac)
plat->phylink_node = np;

/* Get max speed of operation from device tree */
- if (of_property_read_u32(np, "max-speed", &plat->max_speed))
- plat->max_speed = -1;
+ of_property_read_u32(np, "max-speed", &plat->max_speed);

plat->bus_id = of_alias_get_id(np, "ethernet");
if (plat->bus_id < 0)
--
2.34.1

2022-04-01 14:37:32

by Russell King (Oracle)

Subject: Re: [PATCH] net: stmmac: Fix unset max_speed difference between DT and non-DT platforms

On Fri, Apr 01, 2022 at 01:18:27AM +0800, Chen-Yu Tsai wrote:
> From: Chen-Yu Tsai <[email protected]>
>
> In commit 9cbadf094d9d ("net: stmmac: support max-speed device tree
> property"), when DT platforms don't set "max-speed", max_speed is set to
> -1; for non-DT platforms, it stays the default 0.
>
> Prior to commit eeef2f6b9f6e ("net: stmmac: Start adding phylink support"),
> the check for a valid max_speed setting was to check if it was greater
> than zero. This commit got it right, but subsequent patches just checked
> for non-zero, which is incorrect for DT platforms.

Sounds like it's got to complicated...

> In commit 92c3807b9ac3 ("net: stmmac: convert to phylink_get_linkmodes()")
> the conversion switched completely to checking for non-zero value as a
> valid value, which caused 1000base-T to stop getting advertised by
> default.
>
> Instead of trying to fix all the checks, simply leave max_speed alone if
> DT property parsing fails.

And this kind of proves that point - if deleting code fixes it...

Acked-by: Russell King (Oracle) <[email protected]>

--
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