[PATCH v1 1/3] net: ath79: add ag71xx Ethernet driver

[Sascha Hauer]

On Fri, Aug 18, 2017 at 04:02:59PM +0200, Oleksij Rempel wrote:
> From: Yegor Yefremov <yegorslists at googlemail.com>
> 
> Signed-off-by: Yegor Yefremov <yegorslists at googlemail.com>
> Signed-off-by: Antony Pavlov <antonynpavlov at gmail.com>
> ---
>  arch/mips/mach-ath79/include/mach/ar71xx_regs.h |  12 +
>  drivers/net/Kconfig                             |   7 +
>  drivers/net/Makefile                            |   1 +
>  drivers/net/ag71xx.c                            | 530 ++++++++++++++++++++++++
>  4 files changed, 550 insertions(+)
>  create mode 100644 drivers/net/ag71xx.c
> 
> +static int ag71xx_ether_send(struct eth_device *edev, void *packet, int length)
> +{
> +	struct ag71xx *priv = edev->priv;
> +	struct device_d *dev = priv->dev;
> +	ag7240_desc_t *f = &priv->fifo_tx[priv->next_tx];
> +	int i;
> +
> +	/* flush */
> +	dma_sync_single_for_device((unsigned long)packet, length, DMA_TO_DEVICE);
> +
> +	f->pkt_start_addr = virt_to_phys(packet);
> +	f->res1 = 0;
> +	f->pkt_size = length;
> +	f->is_empty = 0;
> +	ag71xx_wr(priv, AG71XX_REG_TX_DESC, virt_to_phys(f));
> +	ag71xx_wr(priv, AG71XX_REG_TX_CTRL, TX_CTRL_TXE);
> +
> +	/* flush again?! */
> +	dma_sync_single_for_cpu((unsigned long)packet, length, DMA_TO_DEVICE);
> +
> +	for (i = 0; i < MAX_WAIT; i++) {
> +		udelay(100);
> +		if (f->is_empty) {
> +			break;
> +		}
> +	}
> +

Use a is_timeout() loop. With this you won't have a minimum delay of
100us and also not a granularity of 100us.

> +	if (i == MAX_WAIT) {
> +		dev_err(dev, "Tx Timed out\n");
> +	}
> +

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