From: Chen-Yu Tsai <wens@csie.org>

The DWMAC 1000 DMA capabilities register does not provide actual
FIFO sizes, nor does the driver really care. If they are not
provided via some other means, the driver will work fine, only
disallowing changing the MTU setting.

Provide the FIFO sizes through the driver's platform data to enable
MTU changes. The FIFO sizes are confirmed to be the same across RK3288,
RK3328, RK3399 and PX30, based on their respective manuals. It is
likely that Rockchip synthesized their DWMAC 1000 with the same
parameters on all their chips that have it.

Signed-off-by: Chen-Yu Tsai <wens@csie.org>
---
Changes since v1:
- Removed references to breakage from commit message as it is already fixed
- Removed Cc stable and Fixes tags
- Rebased onto latest -next
---
 drivers/net/ethernet/stmicro/stmmac/dwmac-rk.c | 5 ++++-
 1 file changed, 4 insertions(+), 1 deletion(-)

diff --git a/drivers/net/ethernet/stmicro/stmmac/dwmac-rk.c b/drivers/net/ethernet/stmicro/stmmac/dwmac-rk.c
index 003fa5cf42c3..e57181ce5f84 100644
--- a/drivers/net/ethernet/stmicro/stmmac/dwmac-rk.c
+++ b/drivers/net/ethernet/stmicro/stmmac/dwmac-rk.c
@@ -1969,8 +1969,11 @@ static int rk_gmac_probe(struct platform_device *pdev)
 	/* If the stmmac is not already selected as gmac4,
 	 * then make sure we fallback to gmac.
 	 */
-	if (!plat_dat->has_gmac4)
+	if (!plat_dat->has_gmac4) {
 		plat_dat->has_gmac = true;
+		plat_dat->rx_fifo_size = 4096;
+		plat_dat->tx_fifo_size = 2048;
+	}
 
 	plat_dat->set_clk_tx_rate = rk_set_clk_tx_rate;
 
-- 
2.39.5

On Wed, Mar 12, 2025 at 08:42:06PM +0800, Chen-Yu Tsai wrote:
> From: Chen-Yu Tsai <wens@csie.org>
> 
> The DWMAC 1000 DMA capabilities register does not provide actual
> FIFO sizes, nor does the driver really care. If they are not
> provided via some other means, the driver will work fine, only
> disallowing changing the MTU setting.
> 
> Provide the FIFO sizes through the driver's platform data to enable
> MTU changes. The FIFO sizes are confirmed to be the same across RK3288,
> RK3328, RK3399 and PX30, based on their respective manuals. It is
> likely that Rockchip synthesized their DWMAC 1000 with the same
> parameters on all their chips that have it.
> 
> Signed-off-by: Chen-Yu Tsai <wens@csie.org>
> ---
> Changes since v1:
> - Removed references to breakage from commit message as it is already fixed
> - Removed Cc stable and Fixes tags
> - Rebased onto latest -next

The tag of the patch should clearly describe the destination tree. It
can be either "net" or "net-next". "netdev" is not a proper tag.
Assuming you removed the "Fixes" tag, you probably want to send the
patch to "net-next".

Thanks,
Michal