The GBETH IPs found on RZ/G3E SoC family are compatible with the stmmac driver.
They have a MAC HW feature register used by this driver to enable respective
features. While the register advertises Tx coe support, it was not enabled by
the driver due to the 'snps,force_thresh_dma_mode' dtsi property.

Switch from 'snps,force_thresh_dma_mode' to 'snps,force_sf_dma_mode' to enable
Tx checksum offload support on both GBETH IPs. While at it, also switch from
'snps,fixed-busrt' to 'nsps,mixed-burst' and remove 'snps,no-pbl-x8' for
optimal DMA configuration. This improvement results in a measurable TCP Tx
performance gains, increasing throughput by 20Mbps.

Signed-off-by: John Madieu <john.madieu.xa@bp.renesas.com>
---
 arch/arm64/boot/dts/renesas/r9a09g047.dtsi | 10 ++++------
 1 file changed, 4 insertions(+), 6 deletions(-)

diff --git a/arch/arm64/boot/dts/renesas/r9a09g047.dtsi b/arch/arm64/boot/dts/renesas/r9a09g047.dtsi
index e4fac7e0d764..b55b113d1f11 100644
--- a/arch/arm64/boot/dts/renesas/r9a09g047.dtsi
+++ b/arch/arm64/boot/dts/renesas/r9a09g047.dtsi
@@ -722,9 +722,8 @@ eth0: ethernet@15c30000 {
 			snps,perfect-filter-entries = <128>;
 			rx-fifo-depth = <8192>;
 			tx-fifo-depth = <8192>;
-			snps,fixed-burst;
-			snps,no-pbl-x8;
-			snps,force_thresh_dma_mode;
+			snps,mixed-burst;
+			snps,force_sf_dma_mode;
 			snps,axi-config = <&stmmac_axi_setup>;
 			snps,mtl-rx-config = <&mtl_rx_setup0>;
 			snps,mtl-tx-config = <&mtl_tx_setup0>;
@@ -823,9 +822,8 @@ eth1: ethernet@15c40000 {
 			snps,perfect-filter-entries = <128>;
 			rx-fifo-depth = <8192>;
 			tx-fifo-depth = <8192>;
-			snps,fixed-burst;
-			snps,no-pbl-x8;
-			snps,force_thresh_dma_mode;
+			snps,mixed-burst;
+			snps,force_sf_dma_mode;
 			snps,axi-config = <&stmmac_axi_setup>;
 			snps,mtl-rx-config = <&mtl_rx_setup1>;
 			snps,mtl-tx-config = <&mtl_tx_setup1>;
-- 
2.25.1

Hi John,

Thanks for your patch!

On Thu, 14 Aug 2025 at 17:35, John Madieu <john.madieu.xa@bp.renesas.com> wrote:
> The GBETH IPs found on RZ/G3E SoC family are compatible with the stmmac driver.
> They have a MAC HW feature register used by this driver to enable respective
> features. While the register advertises Tx coe support, it was not enabled by
> the driver due to the 'snps,force_thresh_dma_mode' dtsi property.
>
> Switch from 'snps,force_thresh_dma_mode' to 'snps,force_sf_dma_mode' to enable
> Tx checksum offload support on both GBETH IPs. While at it, also switch from
> 'snps,fixed-busrt' to 'nsps,mixed-burst' and remove 'snps,no-pbl-x8' for

burst ... snps

> optimal DMA configuration. This improvement results in a measurable TCP Tx
> performance gains, increasing throughput by 20Mbps.
>
> Signed-off-by: John Madieu <john.madieu.xa@bp.renesas.com>

LGTM, so
Reviewed-by: Geert Uytterhoeven <geert+renesas@glider.be>
i.e. will queue in renesas-devel for v6.18, with the typos fixed.

Gr{oetje,eeting}s,

                        Geert

-- 
Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- geert@linux-m68k.org

In personal conversations with technical people, I call myself a hacker. But
when I'm talking to journalists I just say "programmer" or something like that.
                                -- Linus Torvalds