Re: [PATCH net v2] r8169: fix rtl8125b PAUSE frames blasting when suspended

Jacob Keller
2023-11-29T23:05:19Z

On 11/29/2023 7:53 AM, ChunHao Lin wrote:
> When FIFO reaches near full state, device will issue pause frame.
> If pause slot is enabled(set to 1), in this time, device will issue
> pause frame only once. But if pause slot is disabled(set to 0), device
> will keep sending pause frames until FIFO reaches near empty state.
>
> When pause slot is disabled, if there is no one to handle receive
> packets, device FIFO will reach near full state and keep sending
> pause frames. That will impact entire local area network.
>
> This issue can be reproduced in Chromebox (not Chromebook) in
> developer mode running a test image (and v5.10 kernel):
> 1) ping -f $CHROMEBOX (from workstation on same local network)
> 2) run "powerd_dbus_suspend" from command line on the $CHROMEBOX
> 3) ping $ROUTER (wait until ping fails from workstation)
>
> Takes about ~20-30 seconds after step 2 for the local network to
> stop working.
>
> Fix this issue by enabling pause slot to only send pause frame once
> when FIFO reaches near full state.
>

Makes sense. Avoiding the spam is good. The naming is a bit confusing
but I guess that comes from realtek datasheet?

> Fixes: f1bce4ad2f1c ("r8169: add support for RTL8125")
> Reported-by: Grant Grundler <grundler@chromium.org>
> Tested-by: Grant Grundler <grundler@chromium.org>
> Cc: stable@vger.kernel.org
> Signed-off-by: ChunHao Lin <hau@realtek.com>
> ---
> v2:
> - update comment and title.
> ---
> drivers/net/ethernet/realtek/r8169_main.c | 7 ++++++-
> 1 file changed, 6 insertions(+), 1 deletion(-)
>
> diff --git a/drivers/net/ethernet/realtek/r8169_main.c b/drivers/net/ethernet/realtek/r8169_main.c
> index 62cabeeb842a..bb787a52bc75 100644
> --- a/drivers/net/ethernet/realtek/r8169_main.c
> +++ b/drivers/net/ethernet/realtek/r8169_main.c
> @@ -196,6 +196,7 @@ enum rtl_registers {
> /* No threshold before first PCI xfer */
> #define RX_FIFO_THRESH (7 << RXCFG_FIFO_SHIFT)
> #define RX_EARLY_OFF (1 << 11)
> +#define RX_PAUSE_SLOT_ON (1 << 11) /* 8125b and later */

This confuses me though: RX_EARLY_OFF is (1 << 11) as well.. Is that
from a different set of devices? We're writing to the same register
RxConfig here I think in both cases?

Can you clarify if these are supposed to be the same bit?

> #define RXCFG_DMA_SHIFT 8
> /* Unlimited maximum PCI burst. */
> #define RX_DMA_BURST (7 << RXCFG_DMA_SHIFT)
> @@ -2306,9 +2307,13 @@ static void rtl_init_rxcfg(struct rtl8169_private *tp)
> case RTL_GIGA_MAC_VER_40 ... RTL_GIGA_MAC_VER_53:
> RTL_W32(tp, RxConfig, RX128_INT_EN | RX_MULTI_EN | RX_DMA_BURST | RX_EARLY_OFF);
> break;
> - case RTL_GIGA_MAC_VER_61 ... RTL_GIGA_MAC_VER_63:
> + case RTL_GIGA_MAC_VER_61:
> RTL_W32(tp, RxConfig, RX_FETCH_DFLT_8125 | RX_DMA_BURST);
> break;

I assume there isn't a VER_62 between these?

> + case RTL_GIGA_MAC_VER_63:
> + RTL_W32(tp, RxConfig, RX_FETCH_DFLT_8125 | RX_DMA_BURST |
> + RX_PAUSE_SLOT_ON);

We add RX_PAUSE_SLOT_ON now for RTL_GIGA_MAC_VER_63 in addition. Makes
sense.
> + break;
> default:
> RTL_W32(tp, RxConfig, RX128_INT_EN | RX_DMA_BURST);
> break;