[net,2/2] net: dsa: b53: Set correct number of ports in the DSA struct

Commit Message

Rafał Miłecki Sept. 1, 2021, 9:21 a.m. UTC

From: Rafał Miłecki <[e-mail]>

Setting DSA_MAX_PORTS caused DSA to call b53 callbacks (e.g.
b53_disable_port() during dsa_register_switch()) for invalid
(non-existent) ports. That made b53 modify unrelated registers and is
one of reasons for a broken BCM5301x support.

This problem exists for years but DSA_MAX_PORTS usage has changed few
times so it's hard to specify a single commit this change fixes.

Cc: [e-mail]
Signed-off-by: Rafał Miłecki <[e-mail]>
---
 drivers/net/dsa/b53/b53_common.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

Comments

Florian Fainelli Sept. 1, 2021, 5:21 p.m. UTC | #1

On 9/1/2021 2:21 AM, Rafał Miłecki wrote:
> From: Rafał Miłecki <[e-mail]>
> 
> Setting DSA_MAX_PORTS caused DSA to call b53 callbacks (e.g.
> b53_disable_port() during dsa_register_switch()) for invalid
> (non-existent) ports. That made b53 modify unrelated registers and is
> one of reasons for a broken BCM5301x support.
> 
> This problem exists for years but DSA_MAX_PORTS usage has changed few
> times so it's hard to specify a single commit this change fixes.

You should still try to identify the relevant tags that this is fixing 
such that this gets back ported to the appropriate trees. We could use 
Fixes: 7e99e3470172 ("net: dsa: remove dsa_switch_alloc helper"), to 
minimize the amount of work doing the back port.

Jakub Kicinski Sept. 1, 2021, 11:36 p.m. UTC | #2

On Wed, 1 Sep 2021 10:21:55 -0700 Florian Fainelli wrote:
> On 9/1/2021 2:21 AM, Rafał Miłecki wrote:
> > From: Rafał Miłecki <[e-mail]>
> > 
> > Setting DSA_MAX_PORTS caused DSA to call b53 callbacks (e.g.
> > b53_disable_port() during dsa_register_switch()) for invalid
> > (non-existent) ports. That made b53 modify unrelated registers and is
> > one of reasons for a broken BCM5301x support.
> > 
> > This problem exists for years but DSA_MAX_PORTS usage has changed few
> > times so it's hard to specify a single commit this change fixes.  
> 
> You should still try to identify the relevant tags that this is fixing 
> such that this gets back ported to the appropriate trees. We could use 
> Fixes: 7e99e3470172 ("net: dsa: remove dsa_switch_alloc helper"), to 
> minimize the amount of work doing the back port.

To be clear are you okay with the fixes tag you provided or should we
wait for Rafał to double check?

Florian Fainelli Sept. 2, 2021, 1:38 a.m. UTC | #3

On 9/1/2021 4:36 PM, Jakub Kicinski wrote:
> On Wed, 1 Sep 2021 10:21:55 -0700 Florian Fainelli wrote:
>> On 9/1/2021 2:21 AM, Rafał Miłecki wrote:
>>> From: Rafał Miłecki <[e-mail]>
>>>
>>> Setting DSA_MAX_PORTS caused DSA to call b53 callbacks (e.g.
>>> b53_disable_port() during dsa_register_switch()) for invalid
>>> (non-existent) ports. That made b53 modify unrelated registers and is
>>> one of reasons for a broken BCM5301x support.
>>>
>>> This problem exists for years but DSA_MAX_PORTS usage has changed few
>>> times so it's hard to specify a single commit this change fixes.
>>
>> You should still try to identify the relevant tags that this is fixing
>> such that this gets back ported to the appropriate trees. We could use
>> Fixes: 7e99e3470172 ("net: dsa: remove dsa_switch_alloc helper"), to
>> minimize the amount of work doing the back port.
> 
> To be clear are you okay with the fixes tag you provided or should we
> wait for Rafał to double check?

That Fixes tag is correct and won't cause conflicts AFAICT with 
backports all the way down to that commit.

Patch

diff --git a/drivers/net/dsa/b53/b53_common.c b/drivers/net/dsa/b53/b53_common.c
index dcf9d7e5ae14..5646eb8afe38 100644
--- a/drivers/net/dsa/b53/b53_common.c
+++ b/drivers/net/dsa/b53/b53_common.c
@@ -2615,6 +2615,8 @@  static int b53_switch_init(struct b53_device *dev)
 	dev->enabled_ports |= BIT(dev->cpu_port);
 	dev->num_ports = fls(dev->enabled_ports);
 
+	dev->ds->num_ports = min_t(unsigned int, dev->num_ports, DSA_MAX_PORTS);
+
 	/* Include non standard CPU port built-in PHYs to be probed */
 	if (is539x(dev) || is531x5(dev)) {
 		for (i = 0; i < dev->num_ports; i++) {
@@ -2659,7 +2661,6 @@  struct b53_device *b53_switch_alloc(struct device *base,
 		return NULL;
 
 	ds->dev = base;
-	ds->num_ports = DSA_MAX_PORTS;
 
 	dev = devm_kzalloc(base, sizeof(*dev), GFP_KERNEL);
 	if (!dev)