Re: [PATCH 1/2] stmmac: introduce flag to dynamically disable TX offload for rockchip devices

From: Philipp Tomsich
Date: Mon Apr 01 2019 - 15:12:32 EST


+ Christoph.

> On 01.04.2019, at 21:06, Heiko StÃbner <heiko@xxxxxxxxx> wrote:
>
> Am Montag, 1. April 2019, 20:54:45 CEST schrieb Robin Murphy:
>> On 01/04/2019 19:18, Leonidas P. Papadakos wrote:
>>> From: =?UTF-8?q?Kamil=20Trzci=C5=84ski?= <ayufan@xxxxxxxxx>
>>>
>>> Some rockchip boards exhibit an issue where tx checksumming does not work with
>>> packets larger than 1498.
>>
>> Is it really a board-level problem? I'm no networking expert, but the
>> nature of the workaround suggests this is more likely to be some
>> inherent limitation of the IP block in the SoC, rather than something to
>> do with how the external pins get wired up. Does anyone have an RK3328
>> or RK3399 board that provably *does* checksum large packets correctly?
>
> I don't have that many rk3399-boards with actual ethernet and even only
> the rock64 from rk3328-land, but at least my rk3399-firefly also seems
> affected by this.
>
> But so far the rk3399-puma board from Theobroma did not show that ethernet
> issue for me, so I've added two Theobroma people who may or may not tell
> if they've also seen that issue.
>
>>
>>> This is bad for network stability.
>>>
>>> The previous approach was using force_thresh_dma_mode in the board dts, which
>>> does more than we need.
>>
>> If indeed it is a SoC-level thing (or at least we want to treat it as
>> such), then couldn't we just hang it off the existing SoC-specific
>> compatibles in dwmac-rk.c and avoid the need for a new DT property at
>> all? After all, that's precisely why SoC-specific compatibles are a
>> thing in the first place.
>>
>> Robin.
>>
>>> Signed-off-by: Leonidas P. Papadakos <papadakospan@xxxxxxxxx>
>>> ---
>>> drivers/net/ethernet/stmicro/stmmac/stmmac_main.c | 4 ++++
>>> drivers/net/ethernet/stmicro/stmmac/stmmac_platform.c | 2 ++
>>> include/linux/stmmac.h | 1 +
>>> 3 files changed, 7 insertions(+)
>>>
>>> diff --git a/drivers/net/ethernet/stmicro/stmmac/stmmac_main.c b/drivers/net/ethernet/stmicro/stmmac/stmmac_main.c
>>> index 6a2e1031a..4552147e9 100644
>>> --- a/drivers/net/ethernet/stmicro/stmmac/stmmac_main.c
>>> +++ b/drivers/net/ethernet/stmicro/stmmac/stmmac_main.c
>>> @@ -3660,6 +3660,10 @@ static netdev_features_t stmmac_fix_features(struct net_device *dev,
>>> if (priv->plat->bugged_jumbo && (dev->mtu > ETH_DATA_LEN))
>>> features &= ~NETIF_F_CSUM_MASK;
>>>
>>> + /* Including very small MTUs of 1498 for Rockchip devices */
>>> + if (priv->plat->bugged_tx_coe && (dev->mtu > ETH_DATA_LEN - 2))
>>> + features &= ~NETIF_F_CSUM_MASK;
>>> +
>>> /* Disable tso if asked by ethtool */
>>> if ((priv->plat->tso_en) && (priv->dma_cap.tsoen)) {
>>> if (features & NETIF_F_TSO)
>>> diff --git a/drivers/net/ethernet/stmicro/stmmac/stmmac_platform.c b/drivers/net/ethernet/stmicro/stmmac/stmmac_platform.c
>>> index 3031f2bf1..807cf5826 100644
>>> --- a/drivers/net/ethernet/stmicro/stmmac/stmmac_platform.c
>>> +++ b/drivers/net/ethernet/stmicro/stmmac/stmmac_platform.c
>>> @@ -519,6 +519,8 @@ stmmac_probe_config_dt(struct platform_device *pdev, const char **mac)
>>> pr_warn("force_sf_dma_mode is ignored if force_thresh_dma_mode is set.");
>>> }
>>>
>>> + plat->bugged_tx_coe = of_property_read_bool(np, "rockchip,bugged_tx_coe");
>>> +
>>> of_property_read_u32(np, "snps,ps-speed", &plat->mac_port_sel_speed);
>>>
>>> plat->axi = stmmac_axi_setup(pdev);
>>> diff --git a/include/linux/stmmac.h b/include/linux/stmmac.h
>>> index 4335bd771..60c411f43 100644
>>> --- a/include/linux/stmmac.h
>>> +++ b/include/linux/stmmac.h
>>> @@ -162,6 +162,7 @@ struct plat_stmmacenet_data {
>>> int pmt;
>>> int force_sf_dma_mode;
>>> int force_thresh_dma_mode;
>>> + int bugged_tx_coe;
>>> int riwt_off;
>>> int max_speed;
>>> int maxmtu;
>>>
>>
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