Hi David,
Please ignore this one for the moment, I'll have to run few more tests on it.
Thank you,
Claudiu Beznea
On 06.12.2018 19:44, Claudiu Beznea - M18063 wrote:
> From: Claudiu Beznea <claudiu.bez...@microchip.com>
>
> On some platforms (currently detected only on SAMA5D4) TX might stuck
> even the pachets are still present in DMA memories and TX start was
> issued for them. This happens due to race condition between MACB driver
> updating next TX buffer descriptor to be used and IP reading the same
> descriptor. In such a case, the "TX USED BIT READ" interrupt is asserted.
> GEM/MACB user guide specifies that if a "TX USED BIT READ" interrupt
> is asserted TX must be restarted. Restart TX if used bit is read and
> packets are present in software TX queue. Packets are removed from software
> TX queue if TX was successful for them (see macb_tx_interrupt()).
>
> Signed-off-by: Claudiu Beznea <claudiu.bez...@microchip.com>
> ---
> drivers/net/ethernet/cadence/macb_main.c | 21 ++++++++++++++++++++-
> 1 file changed, 20 insertions(+), 1 deletion(-)
>
> diff --git a/drivers/net/ethernet/cadence/macb_main.c
> b/drivers/net/ethernet/cadence/macb_main.c
> index 1d86b4d5645a..f920230386ee 100644
> --- a/drivers/net/ethernet/cadence/macb_main.c
> +++ b/drivers/net/ethernet/cadence/macb_main.c
> @@ -61,7 +61,8 @@
> #define MACB_TX_ERR_FLAGS (MACB_BIT(ISR_TUND) \
> | MACB_BIT(ISR_RLE) \
> | MACB_BIT(TXERR))
> -#define MACB_TX_INT_FLAGS (MACB_TX_ERR_FLAGS | MACB_BIT(TCOMP))
> +#define MACB_TX_INT_FLAGS (MACB_TX_ERR_FLAGS | MACB_BIT(TCOMP) \
> + | MACB_BIT(TXUBR))
>
> /* Max length of transmit frame must be a multiple of 8 bytes */
> #define MACB_TX_LEN_ALIGN 8
> @@ -1312,6 +1313,21 @@ static void macb_hresp_error_task(unsigned long data)
> netif_tx_start_all_queues(dev);
> }
>
> +inline static void macb_tx_restart(struct macb_queue *queue)
> +{
> + unsigned int head = queue->tx_head;
> + unsigned int tail = queue->tx_tail;
> + struct macb *bp = queue->bp;
> +
> + if (bp->caps & MACB_CAPS_ISR_CLEAR_ON_WRITE)
> + queue_writel(queue, ISR, MACB_BIT(TXUBR));
> +
> + if (head == tail)
> + return;
> +
> + macb_writel(bp, NCR, macb_readl(bp, NCR) | MACB_BIT(TSTART));
> +}
> +
> static irqreturn_t macb_interrupt(int irq, void *dev_id)
> {
> struct macb_queue *queue = dev_id;
> @@ -1369,6 +1385,9 @@ static irqreturn_t macb_interrupt(int irq, void *dev_id)
> if (status & MACB_BIT(TCOMP))
> macb_tx_interrupt(queue);
>
> + if (status & MACB_BIT(TXUBR))
> + macb_tx_restart(queue);
> +
> /* Link change detection isn't possible with RMII, so we'll
> * add that if/when we get our hands on a full-blown MII PHY.
> */
>
