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SubjectRe: [PATCH 5/7] net: stmmac: Program RX queue size and flow control
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Às 5:24 PM de 2/23/2017, Thierry Reding escreveu:
> From: Thierry Reding <treding@nvidia.com>
>
> Program the receive queue size based on the RX FIFO size and enable
> hardware flow control for large FIFOs.
>
> Signed-off-by: Thierry Reding <treding@nvidia.com>
> ---
> drivers/net/ethernet/stmicro/stmmac/dwmac4.h | 12 +++++++
> drivers/net/ethernet/stmicro/stmmac/dwmac4_dma.c | 43 ++++++++++++++++++++++--
> 2 files changed, 53 insertions(+), 2 deletions(-)
>
> diff --git a/drivers/net/ethernet/stmicro/stmmac/dwmac4.h b/drivers/net/ethernet/stmicro/stmmac/dwmac4.h
> index db45134fddf0..9acc1f1252b3 100644
> --- a/drivers/net/ethernet/stmicro/stmmac/dwmac4.h
> +++ b/drivers/net/ethernet/stmicro/stmmac/dwmac4.h
> @@ -180,6 +180,7 @@ enum power_event {
> #define MTL_OP_MODE_TSF BIT(1)
>
> #define MTL_OP_MODE_TQS_MASK GENMASK(24, 16)
> +#define MTL_OP_MODE_TQS_SHIFT 16
>
> #define MTL_OP_MODE_TTC_MASK 0x70
> #define MTL_OP_MODE_TTC_SHIFT 4
> @@ -193,6 +194,17 @@ enum power_event {
> #define MTL_OP_MODE_TTC_384 (6 << MTL_OP_MODE_TTC_SHIFT)
> #define MTL_OP_MODE_TTC_512 (7 << MTL_OP_MODE_TTC_SHIFT)
>
> +#define MTL_OP_MODE_RQS_MASK GENMASK(29, 20)
> +#define MTL_OP_MODE_RQS_SHIFT 20
> +
> +#define MTL_OP_MODE_RFD_MASK GENMASK(19, 14)
> +#define MTL_OP_MODE_RFD_SHIFT 14
> +
> +#define MTL_OP_MODE_RFA_MASK GENMASK(13, 8)
> +#define MTL_OP_MODE_RFA_SHIFT 8
> +
> +#define MTL_OP_MODE_EHFC BIT(7)
> +
> #define MTL_OP_MODE_RTC_MASK 0x18
> #define MTL_OP_MODE_RTC_SHIFT 3
>
> diff --git a/drivers/net/ethernet/stmicro/stmmac/dwmac4_dma.c b/drivers/net/ethernet/stmicro/stmmac/dwmac4_dma.c
> index 8d249f3b34c8..03d230201960 100644
> --- a/drivers/net/ethernet/stmicro/stmmac/dwmac4_dma.c
> +++ b/drivers/net/ethernet/stmicro/stmmac/dwmac4_dma.c
> @@ -185,8 +185,9 @@ static void dwmac4_rx_watchdog(void __iomem *ioaddr, u32 riwt)
> }
>
> static void dwmac4_dma_chan_op_mode(void __iomem *ioaddr, int txmode,
> - int rxmode, u32 channel)
> + int rxmode, u32 channel, int rxfifosz)
> {
> + unsigned int rqs = rxfifosz / 256 - 1;
> u32 mtl_tx_op, mtl_rx_op, mtl_rx_int;
>
> /* Following code only done for channel 0, other channels not yet
> @@ -252,6 +253,44 @@ static void dwmac4_dma_chan_op_mode(void __iomem *ioaddr, int txmode,
> mtl_rx_op |= MTL_OP_MODE_RTC_128;
> }
>
> + mtl_rx_op &= ~MTL_OP_MODE_RQS_MASK;
> + mtl_rx_op |= rqs << MTL_OP_MODE_RQS_SHIFT;
> +
> + /* enable flow control only if each channel gets 4 KiB or more FIFO */
> + if (rxfifosz >= 4096) {
> + unsigned int rfd, rfa;
> +
> + mtl_rx_op |= MTL_OP_MODE_EHFC;
> +
> + switch (rxfifosz) {
> + case 4096:
> + rfd = 0x03;
> + rfa = 0x01;
> + break;
> +
> + case 8192:
> + rfd = 0x06;
> + rfa = 0x0a;
> + break;
> +
> + case 16384:
> + rfd = 0x06;
> + rfa = 0x12;
> + break;
> +
> + default:
> + rfd = 0x06;
> + rfa = 0x1e;
> + break;
> + }

Are these RFA and RFD values suitable to any setup using thresholds? Please
justify their values in oerder for other developers to understand them.

> +
> + mtl_rx_op &= ~MTL_OP_MODE_RFD_MASK;
> + mtl_rx_op |= rfd << MTL_OP_MODE_RFD_SHIFT;
> +
> + mtl_rx_op &= ~MTL_OP_MODE_RFA_MASK;
> + mtl_rx_op |= rfa << MTL_OP_MODE_RFA_SHIFT;
> + }
> +
> writel(mtl_rx_op, ioaddr + MTL_CHAN_RX_OP_MODE(channel));
>
> /* Enable MTL RX overflow */
> @@ -264,7 +303,7 @@ static void dwmac4_dma_operation_mode(void __iomem *ioaddr, int txmode,
> int rxmode, int rxfifosz)
> {
> /* Only Channel 0 is actually configured and used */
> - dwmac4_dma_chan_op_mode(ioaddr, txmode, rxmode, 0);
> + dwmac4_dma_chan_op_mode(ioaddr, txmode, rxmode, 0, rxfifosz);

Why not configure tx fifo as well, you already getting it from the features
register.

> }
>
> static void dwmac4_get_hw_feature(void __iomem *ioaddr,
>

Thanks.

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