[net-next PATCH v2] net: phy: correctly check soft_reset ret ONLY if defined for PHY

[net-next PATCH v2] net: phy: correctly check soft_reset ret ONLY if defined for PHY

[Christian Marangi]

Introduced by commit 6e2d85ec0559 ("net: phy: Stop with excessive soft
reset").

soft_reset call for phy_init_hw had multiple revision across the years
and the implementation goes back to 2014. Originally was a simple call
to write the generic PHY reset BIT, it was then moved to a dedicated
function. It was then added the option for PHY driver to define their
own special way to reset the PHY. Till this change, checking for ret was
correct as it was always filled by either the generic reset or the
custom implementation. This changed tho with commit 6e2d85ec0559 ("net:
phy: Stop with excessive soft reset"), as the generic reset call to PHY
was dropped but the ret check was never made entirely optional and
dependent whether soft_reset was defined for the PHY driver or not.

Luckly nothing was ever added before the soft_reset call so the ret
check (in the case where a PHY didn't had soft_reset defined) although
wrong, never caused problems as ret was init 0 at the start of
phy_init_hw.

To prevent any kind of problem and to make the function cleaner and more
robust, correctly move the ret check if the soft_reset section making it
optional and needed only with the function defined.

Signed-off-by: Christian Marangi <ansuelsmth@gmail.com>
Reviewed-by: Larysa Zaremba <larysa.zaremba@intel.com>
---
Changes v2:
- Drop Fixes Tag
- Add Reviewed-by Tag
- Add Introduced by at the top of the commit description

 drivers/net/phy/phy_device.c | 9 ++++-----
 1 file changed, 4 insertions(+), 5 deletions(-)

diff --git a/drivers/net/phy/phy_device.c b/drivers/net/phy/phy_device.c
index 2ce74593d6e4..478126f6b5bc 100644
--- a/drivers/net/phy/phy_device.c
+++ b/drivers/net/phy/phy_device.c
@@ -1235,14 +1235,13 @@ int phy_init_hw(struct phy_device *phydev)
 
 	if (phydev->drv->soft_reset) {
 		ret = phydev->drv->soft_reset(phydev);
+		if (ret < 0)
+			return ret;
+
 		/* see comment in genphy_soft_reset for an explanation */
-		if (!ret)
-			phydev->suspended = 0;
+		phydev->suspended = 0;
 	}
 
-	if (ret < 0)
-		return ret;
-
 	ret = phy_scan_fixups(phydev);
 	if (ret < 0)
 		return ret;
-- 
2.40.1

Re: [net-next PATCH v2] net: phy: correctly check soft_reset ret ONLY if defined for PHY

[Simon Horman]

On Tue, Nov 21, 2023 at 02:53:32PM +0100, Christian Marangi wrote:
> Introduced by commit 6e2d85ec0559 ("net: phy: Stop with excessive soft
> reset").
> 
> soft_reset call for phy_init_hw had multiple revision across the years
> and the implementation goes back to 2014. Originally was a simple call
> to write the generic PHY reset BIT, it was then moved to a dedicated
> function. It was then added the option for PHY driver to define their
> own special way to reset the PHY. Till this change, checking for ret was
> correct as it was always filled by either the generic reset or the
> custom implementation. This changed tho with commit 6e2d85ec0559 ("net:
> phy: Stop with excessive soft reset"), as the generic reset call to PHY
> was dropped but the ret check was never made entirely optional and
> dependent whether soft_reset was defined for the PHY driver or not.
> 
> Luckly nothing was ever added before the soft_reset call so the ret
> check (in the case where a PHY didn't had soft_reset defined) although
> wrong, never caused problems as ret was init 0 at the start of
> phy_init_hw.
> 
> To prevent any kind of problem and to make the function cleaner and more
> robust, correctly move the ret check if the soft_reset section making it
> optional and needed only with the function defined.
> 
> Signed-off-by: Christian Marangi <ansuelsmth@gmail.com>
> Reviewed-by: Larysa Zaremba <larysa.zaremba@intel.com>

I agree that it is good to only check for ret if it could be
indicating an error value. And I see that as a bonus we avoid
a now redundant in the case where phydev->drv->soft_reset is set,
which is nice.

FWIIW, in an ideal world, I think that ret would not be initialised to
0 at the top of the function, because it's unnecessary, and such
defensive programming is not in line with how kernel code is done.

In any case, this patch looks good to me.

Reviewed-by: Simon Horman <horms@kernel.org>

Re: [net-next PATCH v2] net: phy: correctly check soft_reset ret ONLY if defined for PHY

[patchwork-bot+netdevbpf]

Hello:

This patch was applied to netdev/net-next.git (main)
by David S. Miller <davem@davemloft.net>:

On Tue, 21 Nov 2023 14:53:32 +0100 you wrote:
> Introduced by commit 6e2d85ec0559 ("net: phy: Stop with excessive soft
> reset").
> 
> soft_reset call for phy_init_hw had multiple revision across the years
> and the implementation goes back to 2014. Originally was a simple call
> to write the generic PHY reset BIT, it was then moved to a dedicated
> function. It was then added the option for PHY driver to define their
> own special way to reset the PHY. Till this change, checking for ret was
> correct as it was always filled by either the generic reset or the
> custom implementation. This changed tho with commit 6e2d85ec0559 ("net:
> phy: Stop with excessive soft reset"), as the generic reset call to PHY
> was dropped but the ret check was never made entirely optional and
> dependent whether soft_reset was defined for the PHY driver or not.
> 
> [...]

Here is the summary with links:
  - [net-next,v2] net: phy: correctly check soft_reset ret ONLY if defined for PHY
    https://git.kernel.org/netdev/net-next/c/aadbd27f9674

You are awesome, thank you!
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