ar71xx: fix max frame length of the QCA955x SoCs

[openwrt/openwrt.git] / target / linux / ar71xx / files / arch / mips / ath79 / dev-eth.c

diff --git a/target/linux/ar71xx/files/arch/mips/ath79/dev-eth.c b/target/linux/ar71xx/files/arch/mips/ath79/dev-eth.c
index 17b3ec4a6d46a93b91f5ac1050398ec297a3935c..21feeb9ad301fe0ac1ebea2e6fc7b26943cd7049 100644 (file)
--- a/target/linux/ar71xx/files/arch/mips/ath79/dev-eth.c
+++ b/target/linux/ar71xx/files/arch/mips/ath79/dev-eth.c
@@ -981,6 +981,17 @@ void __init ath79_register_eth(unsigned int id)
                pdata->has_gbit = 1;
                pdata->is_ar724x = 1;
 
+               /*
+                * Limit the maximum frame length to 4095 bytes.
+                * Although the documentation says that the hardware
+                * limit is 16383 bytes but that does not work in
+                * practice. It seems that the hardware only updates
+                * the lowest 12 bits of the packet length field
+                * in the RX descriptor.
+                */
+               pdata->max_frame_len = SZ_4K - 1;
+               pdata->desc_pktlen_mask = SZ_16K - 1;
+
                if (!pdata->fifo_cfg1)
                        pdata->fifo_cfg1 = 0x0010ffff;
                if (!pdata->fifo_cfg2)