Re: [PATCH net-next 25/30] net: dsa: mt7530: properly set MT7531_CPU_PMAP

Arınç ÜNAL
2023-06-04T08:23:32Z

On 26.05.2023 18:51, Vladimir Oltean wrote:
> On Mon, May 22, 2023 at 03:15:27PM +0300, arinc9.unal@gmail.com wrote:
>> From: Arınç ÜNAL <arinc.unal@arinc9.com>
>>
>> Every bit of the CPU port bitmap for MT7531 and the switch on the MT7988
>> SoC represents a CPU port to trap frames to. Currently only the bit that
>> corresponds to the first found CPU port is set on the bitmap. Introduce the
>> MT7531_CPU_PMAP macro to individually set the bits of the CPU port bitmap.
>> Set the CPU port bitmap for MT7531 and the switch on the MT7988 SoC on
>> mt753x_cpu_port_enable() which runs on a loop for each CPU port. Add
>> comments to explain this.
>>
>> According to the document MT7531 Reference Manual for Development Board
>> v1.0, the MT7531_CPU_PMAP bits are unset after reset so no need to clear it
>> beforehand. Since there's currently no public document for the switch on
>> the MT7988 SoC, I assume this is also the case for this switch.
>>
>> Tested-by: Arınç ÜNAL <arinc.unal@arinc9.com>
>> Signed-off-by: Arınç ÜNAL <arinc.unal@arinc9.com>
>> ---
>
> Is this supposed to be a bug fix? (incompatibility with past or future
> device trees also counts as bugs) If so, it needs a Fixes: tag and to be
> targeted towards the "net" tree. Also, the impact of the current behavior
> and of the change need to be explained better.

Yes, this fixes a bug for future devicetrees. I will send this to net
with a more detailed explanation, thanks.

>
>> drivers/net/dsa/mt7530.c | 15 ++++++++-------
>> drivers/net/dsa/mt7530.h | 3 ++-
>> 2 files changed, 10 insertions(+), 8 deletions(-)
>>
>> diff --git a/drivers/net/dsa/mt7530.c b/drivers/net/dsa/mt7530.c
>> index 58d8738d94d3..0b513e3628fe 100644
>> --- a/drivers/net/dsa/mt7530.c
>> +++ b/drivers/net/dsa/mt7530.c
>> @@ -963,6 +963,13 @@ mt753x_cpu_port_enable(struct dsa_switch *ds, int port)
>> mt7530_rmw(priv, MT753X_MFC, MT7530_CPU_MASK, MT7530_CPU_EN |
>> MT7530_CPU_PORT(port));
>>
>> + /* Add the CPU port to the CPU port bitmap for MT7531 and the switch on
>> + * the MT7988 SoC. Any frames set for trapping to CPU port will be
>> + * trapped to the CPU port the user port is affine to.
>> + */
>> + if (priv->id == ID_MT7531 || priv->id == ID_MT7988)
>> + mt7530_set(priv, MT7531_CFC, MT7531_CPU_PMAP(BIT(port)));
>> +
>
> Stylistically, the existence of an indirect call to priv->info->cpu_port_config()
> per switch family is a bit dissonant with an explicit check for device id later
> in the same function.

mt753x_cpu_port_enable() is not being called from
priv->info->cpu_port_config() though. I'm not sure how I would do this
without the device ID check here.

>
>> /* CPU port gets connected to all user ports of
>> * the switch.
>> */
>> @@ -2315,15 +2322,9 @@ static int
>> mt7531_setup_common(struct dsa_switch *ds)
>> {
>> struct mt7530_priv *priv = ds->priv;
>> - struct dsa_port *cpu_dp;
>> int ret, i;
>>
>> - /* BPDU to CPU port */
>> - dsa_switch_for_each_cpu_port(cpu_dp, ds) {
>> - mt7530_rmw(priv, MT7531_CFC, MT7531_CPU_PMAP_MASK,
>> - BIT(cpu_dp->index));
>> - break;
>> - }
>> + /* Trap BPDUs to the CPU port(s) */
>> mt7530_rmw(priv, MT753X_BPC, MT753X_BPDU_PORT_FW_MASK,
>> MT753X_BPDU_CPU_ONLY);
>>
>> diff --git a/drivers/net/dsa/mt7530.h b/drivers/net/dsa/mt7530.h
>> index 5ebb942b07ef..fd2a2f726b8a 100644
>> --- a/drivers/net/dsa/mt7530.h
>> +++ b/drivers/net/dsa/mt7530.h
>> @@ -53,7 +53,8 @@ enum mt753x_id {
>> #define MT7531_MIRROR_MASK (0x7 << 16)
>> #define MT7531_MIRROR_PORT_GET(x) (((x) >> 16) & 0x7)
>> #define MT7531_MIRROR_PORT_SET(x) (((x) & 0x7) << 16)
>> -#define MT7531_CPU_PMAP_MASK GENMASK(7, 0)
>> +#define MT7531_CPU_PMAP(x) ((x) & 0xff)
>
> You can leave this as ((x) & GENMASK(7, 0))

Now that I've read Russell's comment on the previous patch, the below
would be even better?

MT7531_CPU_PMAP(x) FIELD_PREP(MT7531_CPU_PMAP_MASK, x)

>
>> +#define MT7531_CPU_PMAP_MASK MT7531_CPU_PMAP(~0)
>
> There's no other user of MT7531_CPU_PMAP_MASK, you can remove this.

Should I do above or remove this?

Arınç