Re: [PATCH] hw/dma/xilinx_axidma: Check DMASR.HALTED to prevent infinite loop.

[Frank Chang <frank.chang@sifive.com>]

[-- Attachment #1: Type: text/plain, Size: 2467 bytes --]

Reviewed-by: Frank Chang <frank.chang@sifive.com>

On Fri, May 19, 2023 at 2:23 PM Tommy Wu <tommy.wu@sifive.com> wrote:

> When we receive a packet from the xilinx_axienet and then try to s2mem
> through the xilinx_axidma, if the descriptor ring buffer is full in the
> xilinx axidma driver, we’ll assert the DMASR.HALTED in the
> function : stream_process_s2mem and return 0. In the end, we’ll be stuck in
> an infinite loop in axienet_eth_rx_notify.
>
> This patch checks the DMASR.HALTED state when we try to push data
> from xilinx axi-enet to xilinx axi-dma. When the DMASR.HALTED is asserted,
> we will not keep pushing the data and then prevent the infinte loop.
>
> Signed-off-by: Tommy Wu <tommy.wu@sifive.com>
> ---
>  hw/dma/xilinx_axidma.c | 11 ++++++++---
>  1 file changed, 8 insertions(+), 3 deletions(-)
>
> diff --git a/hw/dma/xilinx_axidma.c b/hw/dma/xilinx_axidma.c
> index 6030c76435..12c90267df 100644
> --- a/hw/dma/xilinx_axidma.c
> +++ b/hw/dma/xilinx_axidma.c
> @@ -168,6 +168,11 @@ static inline int stream_idle(struct Stream *s)
>      return !!(s->regs[R_DMASR] & DMASR_IDLE);
>  }
>
> +static inline int stream_halted(struct Stream *s)
> +{
> +    return !!(s->regs[R_DMASR] & DMASR_HALTED);
> +}
> +
>  static void stream_reset(struct Stream *s)
>  {
>      s->regs[R_DMASR] = DMASR_HALTED;  /* starts up halted.  */
> @@ -269,7 +274,7 @@ static void stream_process_mem2s(struct Stream *s,
> StreamSink *tx_data_dev,
>      uint64_t addr;
>      bool eop;
>
> -    if (!stream_running(s) || stream_idle(s)) {
> +    if (!stream_running(s) || stream_idle(s) || stream_halted(s)) {
>          return;
>      }
>
> @@ -326,7 +331,7 @@ static size_t stream_process_s2mem(struct Stream *s,
> unsigned char *buf,
>      unsigned int rxlen;
>      size_t pos = 0;
>
> -    if (!stream_running(s) || stream_idle(s)) {
> +    if (!stream_running(s) || stream_idle(s) || stream_halted(s)) {
>          return 0;
>      }
>
> @@ -407,7 +412,7 @@ xilinx_axidma_data_stream_can_push(StreamSink *obj,
>      XilinxAXIDMAStreamSink *ds = XILINX_AXI_DMA_DATA_STREAM(obj);
>      struct Stream *s = &ds->dma->streams[1];
>
> -    if (!stream_running(s) || stream_idle(s)) {
> +    if (!stream_running(s) || stream_idle(s) || stream_halted(s)) {
>          ds->dma->notify = notify;
>          ds->dma->notify_opaque = notify_opaque;
>          return false;
> --
> 2.31.1
>
>
>

[-- Attachment #2: Type: text/html, Size: 3097 bytes --]