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Date:   Mon, 13 Jan 2020 06:54:06 -0800
From:   Jakub Kicinski <kuba@kernel.org>
To:     Jose Abreu <Jose.Abreu@synopsys.com>
Cc:     netdev@vger.kernel.org, Joao Pinto <Joao.Pinto@synopsys.com>,
        Giuseppe Cavallaro <peppe.cavallaro@st.com>,
        Alexandre Torgue <alexandre.torgue@st.com>,
        "David S. Miller" <davem@davemloft.net>,
        Maxime Coquelin <mcoquelin.stm32@gmail.com>,
        linux-stm32@st-md-mailman.stormreply.com,
        linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org
Subject: Re: [PATCH net-next v2 1/8] net: stmmac: Initial support for TBS
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        <d72e539523e063a391391d447ece658524bb8d57.1578920366.git.Jose.Abreu@synopsys.com>
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On Mon, 13 Jan 2020 14:02:36 +0100, Jose Abreu wrote:
> Adds the initial hooks for TBS support. This needs a 32 byte descriptor
> in order for it to work with current HW. Adds all the logic for Enhanced
> Descriptors in main core but no HW related logic for now.
> 
> Signed-off-by: Jose Abreu <Jose.Abreu@synopsys.com>

> diff --git a/drivers/net/ethernet/stmicro/stmmac/stmmac.h b/drivers/net/ethernet/stmicro/stmmac/stmmac.h
> index f98c5eefb382..dceaeb72a414 100644
> --- a/drivers/net/ethernet/stmicro/stmmac/stmmac.h
> +++ b/drivers/net/ethernet/stmicro/stmmac/stmmac.h
> @@ -42,10 +42,13 @@ struct stmmac_tx_info {
>  /* Frequently used values are kept adjacent for cache effect */
>  struct stmmac_tx_queue {
>  	u32 tx_count_frames;
> +	int tbs_avail;
> +	int tbs_en;

These could be bool or a bitfield?

>  	struct timer_list txtimer;
>  	u32 queue_index;
>  	struct stmmac_priv *priv_data;
>  	struct dma_extended_desc *dma_etx ____cacheline_aligned_in_smp;
> +	struct dma_edesc *dma_entx ____cacheline_aligned_in_smp;

Won't this create a cache line-sized hole? Is the structure member
supposed to be aligned or the data its pointing to?

>  	struct dma_desc *dma_tx;
>  	struct sk_buff **tx_skbuff;
>  	struct stmmac_tx_info *tx_skbuff_dma;

> diff --git a/include/linux/stmmac.h b/include/linux/stmmac.h
> index 0531afa9b21e..19190c609282 100644
> --- a/include/linux/stmmac.h
> +++ b/include/linux/stmmac.h
> @@ -139,6 +139,7 @@ struct stmmac_txq_cfg {
>  	u32 low_credit;
>  	bool use_prio;
>  	u32 prio;
> +	int tbs_en;

also bool?

>  };
>  
>  struct plat_stmmacenet_data {