Re: [PATCH net-next 1/2] net: stmmac: dwmac4: Read the UC filter size from hardware capabilities
From: Nicolai Buchwitz
Date: Mon Aug 31 2026 - 08:27:32 EST
On 31.8.2026 14:15, Maxime Chevallier wrote:
On 8/31/26 14:04, Nicolai Buchwitz wrote:
Hi Maxime
On 31.8.2026 09:01, Maxime Chevallier wrote:
dwmac4 has multiple banks of perfect filter entries, independently
configurable during IP integration.
The multi_addr bank reports a number between 0 and 31 corresponding to
the actual number of entries in that bank, while the 32 and 64 banks
are all-or-nothing.
Expose these caps over debugfs as well.
Signed-off-by: Maxime Chevallier <maxime.chevallier@xxxxxxxxxxx>
---
[...]
diff --git a/drivers/net/ethernet/stmicro/stmmac/dwmac4.h b/drivers/net/ethernet/stmicro/stmmac/dwmac4.h
index 6382836828ba..89368e34a388 100644
--- a/drivers/net/ethernet/stmicro/stmmac/dwmac4.h
+++ b/drivers/net/ethernet/stmicro/stmmac/dwmac4.h
@@ -176,7 +176,9 @@ enum power_event {
/* MAC HW features0 bitmap */
#define GMAC_HW_FEAT_SAVLANINS BIT(27)
-#define GMAC_HW_FEAT_ADDMAC BIT(18)
+#define GMAC_HW_FEAT_MACADR64SEL BIT(24)
+#define GMAC_HW_FEAT_MACADR32SEL BIT(23)
+#define GMAC_HW_FEAT_ADDMAC GENMASK(22, 18)
#define GMAC_HW_FEAT_RXCOESEL BIT(16)
#define GMAC_HW_FEAT_TXCOSEL BIT(14)
#define GMAC_HW_FEAT_EEESEL BIT(13)
diff --git a/drivers/net/ethernet/stmicro/stmmac/dwmac4_dma.c b/drivers/net/ethernet/stmicro/stmmac/dwmac4_dma.c
index 23ffe1adcd0d..14ac3f0e51f7 100644
--- a/drivers/net/ethernet/stmicro/stmmac/dwmac4_dma.c
+++ b/drivers/net/ethernet/stmicro/stmmac/dwmac4_dma.c
@@ -388,6 +388,8 @@ static int dwmac4_get_hw_feature(void __iomem *ioaddr,
dma_cap->half_duplex = (hw_cap & GMAC_HW_FEAT_HDSEL) >> 2;
dma_cap->vlhash = (hw_cap & GMAC_HW_FEAT_VLHASH) >> 4;
dma_cap->multi_addr = (hw_cap & GMAC_HW_FEAT_ADDMAC) >> 18;
Now that ADDMAC has grown from single bit to a mask, the hardcoded 18 has to match
dwmac4.h. So IMHO it would make sense to use FIELD_GET() here (like actphyif)?
It's hardcoded all over, if you look at how all the other fields from the features
are read. I can change it if you really think it's worth, however I'd rather
do a proper cleanup of how all the properties are read at once :)
Perfectly fine for me. Ran into a similar, but unrelated issue recently, so I just
wanted to flag it (for the future) :)
+ dma_cap->additional_32_addr = (hw_cap & GMAC_HW_FEAT_MACADR32SEL) >> 23;
+ dma_cap->additional_64_addr = (hw_cap & GMAC_HW_FEAT_MACADR64SEL) >> 24;
dma_cap->pcs = (hw_cap & GMAC_HW_FEAT_PCSSEL) >> 3;
dma_cap->sma_mdio = (hw_cap & GMAC_HW_FEAT_SMASEL) >> 5;
dma_cap->pmt_remote_wake_up = (hw_cap & GMAC_HW_FEAT_RWKSEL) >> 6;
diff --git a/drivers/net/ethernet/stmicro/stmmac/stmmac_main.c b/drivers/net/ethernet/stmicro/stmmac/stmmac_main.c
index f2fc89176654..a885f8cfef21 100644
--- a/drivers/net/ethernet/stmicro/stmmac/stmmac_main.c
+++ b/drivers/net/ethernet/stmicro/stmmac/stmmac_main.c
@@ -6580,6 +6580,18 @@ static int stmmac_dma_cap_show(struct seq_file *seq, void *v)
seq_printf(seq,
"\tNumber of Additional MAC address registers: %d\n",
priv->dma_cap.multi_addr);
+ } else if (priv->plat->core_type == DWMAC_CORE_GMAC4) {
+ seq_printf(seq,
+ "\tNumber of MAC address registers (1-31): %d\n",
+ priv->dma_cap.multi_addr);
+ seq_printf(seq,
+ "\tAdditional 32 MAC address registers (32-63): %s\n",
+ priv->dma_cap.additional_32_addr ? "Y" : "N");
+ seq_printf(seq,
+ "\tAdditional 64 MAC address registers (64-127): %s\n",
+ priv->dma_cap.additional_64_addr ? "Y" : "N");
+ seq_printf(seq, "\tHash Filter: %s\n",
+ (priv->dma_cap.hash_filter) ? "Y" : "N");
hash_filter seems to be only set in dwmac1000_dma.c? So on dwmac4 it would always print N?
Yeah but dwmac4 has a hash filter, but same as the UC filter it's just not plumbed
in :/
Let's leave this flag here, hash filter addition for MC filtering is coming-up, so let's not
drop it now only to re-enable it after, one of the other wonderful discoveries found by
running the selftests...
Also fine with me.
} else {
seq_printf(seq, "\tHash Filter: %s\n",
(priv->dma_cap.hash_filter) ? "Y" : "N");
Thanks,
Nicolai
Maxime
With both comments addressed and agreed to keep it as is until a cleanup in the future:
Reviewed-by: Nicolai Buchwitz <nb@xxxxxxxxxxx>
Thanks,
Nicolai