Re: [PATCH] net: dsa: sja1105: fix speed setting for 10 MBPS

2020-05-02 Thread Sergei Shtylyov

Hello!

On 01.05.2020 16:43, Colin King wrote:


From: Colin Ian King 

The current logic for speed checking will never set the speed to 10 MBPS
because bmcr & BMCR_SPEED10 is always 0 since BMCR_SPEED10 is 0. Also
the erroneous setting where BMCR_SPEED1000 and BMCR_SPEED100 are both
set causes the speed to be 1000 MBS.  Fix this by masking bps and checking
for just the expected settings of BMCR_SPEED1000, BMCR_SPEED100 and
BMCR_SPEED10 and defaulting to the unknown speed otherwise.

Addresses-Coverity: ("Logically dead code")
Fixes: ffe10e679cec ("net: dsa: sja1105: Add support for the SGMII port")
Signed-off-by: Colin Ian King 
---
  drivers/net/dsa/sja1105/sja1105_main.c | 11 +++
  1 file changed, 7 insertions(+), 4 deletions(-)

diff --git a/drivers/net/dsa/sja1105/sja1105_main.c 
b/drivers/net/dsa/sja1105/sja1105_main.c
index 472f4eb20c49..59a9038cdc4e 100644
--- a/drivers/net/dsa/sja1105/sja1105_main.c
+++ b/drivers/net/dsa/sja1105/sja1105_main.c
@@ -1600,6 +1600,7 @@ static const char * const sja1105_reset_reasons[] = {
  int sja1105_static_config_reload(struct sja1105_private *priv,
 enum sja1105_reset_reason reason)
  {
+   const int mask = (BMCR_SPEED1000 | BMCR_SPEED100 | BMCR_SPEED10);


   Why not declare it in the block it's used in? Also, () not needed here.


struct ptp_system_timestamp ptp_sts_before;
struct ptp_system_timestamp ptp_sts_after;
struct sja1105_mac_config_entry *mac;
@@ -1684,14 +1685,16 @@ int sja1105_static_config_reload(struct sja1105_private 
*priv,
sja1105_sgmii_pcs_config(priv, an_enabled, false);
  
  		if (!an_enabled) {

-   int speed = SPEED_UNKNOWN;
+   int speed;


   Why not the following?

int mask = bmcr & (BMCR_SPEED1000 | BMCR_SPEED100 |
   BMCR_SPEED10);   

  
-			if (bmcr & BMCR_SPEED1000)

+   if ((bmcr & mask) == BMCR_SPEED1000)
speed = SPEED_1000;
-   else if (bmcr & BMCR_SPEED100)
+   else if ((bmcr & mask) == BMCR_SPEED100)
speed = SPEED_100;
-   else if (bmcr & BMCR_SPEED10)
+   else if ((bmcr & mask) == BMCR_SPEED10)
speed = SPEED_10;
+   else
+   speed = SPEED_UNKNOWN;
  
  			sja1105_sgmii_pcs_force_speed(priv, speed);

}


MBR, Sergei


Re: [PATCH] net: dsa: sja1105: fix speed setting for 10 MBPS

2020-05-01 Thread Russell King - ARM Linux admin
On Fri, May 01, 2020 at 06:00:52PM +, Walter Harms wrote:
> IMHO it would be better to use switch case here to improve readability.
> 
> switch (bmcr & mask) {
> 
> case  BMCR_SPEED1000:
>  speed = SPEED_1000;
>  break;
> case  BMCR_SPEED100:
>  speed = SPEED_100;
>  break;
> case  BMCR_SPEED10:
>  speed = SPEED_10;
>  break;
> default:
> speed = SPEED_UNKNOWN
> }
> 
> jm2c,
>  wh
> 
> btw: an_enabled ? why not !enabled, mich more easy to read

You misinterpret "an_enabled".  It's not "negated enabled".  It's not
even "disabled".  It's short for "autonegotiation enabled".  It's
positive logic too.

-- 
RMK's Patch system: https://www.armlinux.org.uk/developer/patches/
FTTC broadband for 0.8mile line in suburbia: sync at 10.2Mbps down 587kbps up