[PATCH net-next 0/2] net: stmmac: remove unused and unimplemented AXI properties

[PATCH net-next 0/2] net: stmmac: remove unused and unimplemented AXI properties

[Russell King (Oracle)]

commit afea03656add ("stmmac: rework DMA bus setting and introduce new
platform AXI structure") added support for parsing all the stmmac AXI
attributes, and added code to set most of the appropriate register bits
with three exceptions:

	snps,kbbe
	snps,mb
	snps,rb

These were parsed by the driver, but the result of parsing was never
used by any of the cores.

Moreover, no DTS in the kernel makes use of these properties.

Thus, it doesn't make sense for the driver to parse these, so let's
remove them. Also remove them from the DT binding document.

 Documentation/devicetree/bindings/net/snps,dwmac.yaml | 18 ------------------
 drivers/net/ethernet/stmicro/stmmac/dwmac-motorcomm.c |  1 -
 drivers/net/ethernet/stmicro/stmmac/stmmac_platform.c |  3 ---
 include/linux/stmmac.h                                |  3 ---
 4 files changed, 25 deletions(-)

-- 
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[PATCH net-next 1/2] net: stmmac: remove axi_kbbe, axi_mb and axi_rb members

[Russell King (Oracle)]

axi_kbbe, axi_mb and axi_rb are all written, but nothing ever reads
their values. Remove the code that sets these and the struct members.

Signed-off-by: Russell King (Oracle) <rmk+kernel@armlinux.org.uk>
---
 drivers/net/ethernet/stmicro/stmmac/dwmac-motorcomm.c | 1 -
 drivers/net/ethernet/stmicro/stmmac/stmmac_platform.c | 3 ---
 include/linux/stmmac.h                                | 3 ---
 3 files changed, 7 deletions(-)

diff --git a/drivers/net/ethernet/stmicro/stmmac/dwmac-motorcomm.c b/drivers/net/ethernet/stmicro/stmmac/dwmac-motorcomm.c
index d245546b90db..02c786ce5dd4 100644
--- a/drivers/net/ethernet/stmicro/stmmac/dwmac-motorcomm.c
+++ b/drivers/net/ethernet/stmicro/stmmac/dwmac-motorcomm.c
@@ -231,7 +231,6 @@ motorcomm_default_plat_data(struct pci_dev *pdev)
 
 	plat->axi->axi_wr_osr_lmt	= 1;
 	plat->axi->axi_rd_osr_lmt	= 1;
-	plat->axi->axi_mb		= true;
 	plat->axi->axi_blen_regval	= DMA_AXI_BLEN4 | DMA_AXI_BLEN8 |
 					  DMA_AXI_BLEN16 | DMA_AXI_BLEN32;
 
diff --git a/drivers/net/ethernet/stmicro/stmmac/stmmac_platform.c b/drivers/net/ethernet/stmicro/stmmac/stmmac_platform.c
index 545b8a3425eb..5cae2aa72906 100644
--- a/drivers/net/ethernet/stmicro/stmmac/stmmac_platform.c
+++ b/drivers/net/ethernet/stmicro/stmmac/stmmac_platform.c
@@ -109,10 +109,7 @@ static struct stmmac_axi *stmmac_axi_setup(struct platform_device *pdev)
 
 	axi->axi_lpi_en = of_property_read_bool(np, "snps,lpi_en");
 	axi->axi_xit_frm = of_property_read_bool(np, "snps,xit_frm");
-	axi->axi_kbbe = of_property_read_bool(np, "snps,kbbe");
 	axi->axi_fb = of_property_read_bool(np, "snps,fb");
-	axi->axi_mb = of_property_read_bool(np, "snps,mb");
-	axi->axi_rb =  of_property_read_bool(np, "snps,rb");
 
 	if (of_property_read_u32(np, "snps,wr_osr_lmt", &axi->axi_wr_osr_lmt))
 		axi->axi_wr_osr_lmt = 1;
diff --git a/include/linux/stmmac.h b/include/linux/stmmac.h
index 5b2bece81448..eaaee329ef9d 100644
--- a/include/linux/stmmac.h
+++ b/include/linux/stmmac.h
@@ -133,10 +133,7 @@ struct stmmac_axi {
 	u32 axi_blen_regval;
 	bool axi_lpi_en;
 	bool axi_xit_frm;
-	bool axi_kbbe;
 	bool axi_fb;
-	bool axi_mb;
-	bool axi_rb;
 };
 
 struct stmmac_rxq_cfg {
-- 
2.47.3

Re: [PATCH net-next 1/2] net: stmmac: remove axi_kbbe, axi_mb and axi_rb members

[Simon Horman]

On Tue, Mar 24, 2026 at 10:05:40AM +0000, Russell King (Oracle) wrote:
> axi_kbbe, axi_mb and axi_rb are all written, but nothing ever reads
> their values. Remove the code that sets these and the struct members.
> 
> Signed-off-by: Russell King (Oracle) <rmk+kernel@armlinux.org.uk>

Hi Russell,

FYI, AI review suggests that these fields should also be removed from
Documentation/networking/device_drivers/ethernet/stmicro/stmmac.rst

Re: [PATCH net-next 1/2] net: stmmac: remove axi_kbbe, axi_mb and axi_rb members

[Russell King (Oracle)]

On Thu, Mar 26, 2026 at 05:29:43PM +0000, Simon Horman wrote:
> On Tue, Mar 24, 2026 at 10:05:40AM +0000, Russell King (Oracle) wrote:
> > axi_kbbe, axi_mb and axi_rb are all written, but nothing ever reads
> > their values. Remove the code that sets these and the struct members.
> > 
> > Signed-off-by: Russell King (Oracle) <rmk+kernel@armlinux.org.uk>
> 
> Hi Russell,
> 
> FYI, AI review suggests that these fields should also be removed from
> Documentation/networking/device_drivers/ethernet/stmicro/stmmac.rst

I noticed. I've prepared an update if netdev folk want that to happen
as I've noticed that that documentation is fairly out of date now.

Do we think it's still useful, or should we consider deleting or
trimming it down? Would it be better to move the struct definitions
into the header file and making the header file part of the docs so
that the documentation is local to the structs?

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Re: [PATCH net-next 1/2] net: stmmac: remove axi_kbbe, axi_mb and axi_rb members

[Russell King (Oracle)]

On Thu, Mar 26, 2026 at 05:47:32PM +0000, Russell King (Oracle) wrote:
> On Thu, Mar 26, 2026 at 05:29:43PM +0000, Simon Horman wrote:
> > On Tue, Mar 24, 2026 at 10:05:40AM +0000, Russell King (Oracle) wrote:
> > > axi_kbbe, axi_mb and axi_rb are all written, but nothing ever reads
> > > their values. Remove the code that sets these and the struct members.
> > > 
> > > Signed-off-by: Russell King (Oracle) <rmk+kernel@armlinux.org.uk>
> > 
> > Hi Russell,
> > 
> > FYI, AI review suggests that these fields should also be removed from
> > Documentation/networking/device_drivers/ethernet/stmicro/stmmac.rst
> 
> I noticed. I've prepared an update if netdev folk want that to happen
> as I've noticed that that documentation is fairly out of date now.

There's another reason I haven't submitted an update, and that's
because netdev is fairly backlogged at the moment - currently there's
381 patches in patchwork - four pages of patchwork, with the oldest
"new" patch dated 21st March. I don't think netdev patchwork needs
more patches at the moment!

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[PATCH net-next 2/2] dt-bindings: remove unimplemented AXI snps,kbbe snps,mb and snps,rb

[Russell King (Oracle)]

Remove the AXI snps,kbbe snps,mb and snps,rb properties as they have
not been used, and although the driver parses these, the code hasn't
ever used the parsed result. This parsing has now been removed.

These were introduced by commit afea03656add ("stmmac: rework DMA bus
setting and introduce new platform AXI structure").

Signed-off-by: Russell King (Oracle) <rmk+kernel@armlinux.org.uk>
---
 .../devicetree/bindings/net/snps,dwmac.yaml    | 18 ------------------
 1 file changed, 18 deletions(-)

diff --git a/Documentation/devicetree/bindings/net/snps,dwmac.yaml b/Documentation/devicetree/bindings/net/snps,dwmac.yaml
index 98ebb6276bc6..6d4afd824418 100644
--- a/Documentation/devicetree/bindings/net/snps,dwmac.yaml
+++ b/Documentation/devicetree/bindings/net/snps,dwmac.yaml
@@ -203,11 +203,8 @@ title: Synopsys DesignWare MAC
         * snps,xit_frm, unlock on WoL
         * snps,wr_osr_lmt, max write outstanding req. limit
         * snps,rd_osr_lmt, max read outstanding req. limit
-        * snps,kbbe, do not cross 1KiB boundary.
         * snps,blen, this is a vector of supported burst length.
         * snps,fb, fixed-burst
-        * snps,mb, mixed-burst
-        * snps,rb, rebuild INCRx Burst
 
   snps,mtl-rx-config:
     $ref: /schemas/types.yaml#/definitions/phandle
@@ -587,11 +584,6 @@ title: Synopsys DesignWare MAC
         description:
           max read outstanding req. limit
 
-      snps,kbbe:
-        $ref: /schemas/types.yaml#/definitions/flag
-        description:
-          do not cross 1KiB boundary.
-
       snps,blen:
         $ref: /schemas/types.yaml#/definitions/uint32-array
         description:
@@ -604,16 +596,6 @@ title: Synopsys DesignWare MAC
         description:
           fixed-burst
 
-      snps,mb:
-        $ref: /schemas/types.yaml#/definitions/flag
-        description:
-          mixed-burst
-
-      snps,rb:
-        $ref: /schemas/types.yaml#/definitions/flag
-        description:
-          rebuild INCRx Burst
-
 required:
   - compatible
   - reg
-- 
2.47.3

Re: [PATCH net-next 2/2] dt-bindings: remove unimplemented AXI snps,kbbe snps,mb and snps,rb

[Conor Dooley]

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On Tue, Mar 24, 2026 at 10:05:45AM +0000, Russell King (Oracle) wrote:
> Remove the AXI snps,kbbe snps,mb and snps,rb properties as they have
> not been used, and although the driver parses these, the code hasn't
> ever used the parsed result. This parsing has now been removed.
> 
> These were introduced by commit afea03656add ("stmmac: rework DMA bus
> setting and introduce new platform AXI structure").
> 
> Signed-off-by: Russell King (Oracle) <rmk+kernel@armlinux.org.uk>
> ---

Acked-by: Conor Dooley <conor.dooley@microchip.com>

Cheers,
Conor.

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