Re: [PATCH] bcm2835_dma: Fix TD mode

["Philippe Mathieu-Daudé" <philmd@redhat.com>]

Hi Rene,

On 1/24/20 6:55 PM, Rene Stange wrote:
> TD (two dimensions) DMA mode did not work, because the xlen variable has
> not been re-initialized before each additional ylen run through in
> bcm2835_dma_update(). Furthermore ylen has to be increased by one after
> reading it from the TXFR_LEN register, because a value of zero has to
> result in one run through of the ylen loop. Both issues have been fixed.

What were you running, how can we reproduce?

> 
> Signed-off-by: Rene Stange <rsta2@o2online.de>
> ---
>   hw/dma/bcm2835_dma.c | 9 +++++----
>   1 file changed, 5 insertions(+), 4 deletions(-)
> 
> diff --git a/hw/dma/bcm2835_dma.c b/hw/dma/bcm2835_dma.c
> index 1e458d7fba..0881c9506e 100644
> --- a/hw/dma/bcm2835_dma.c
> +++ b/hw/dma/bcm2835_dma.c
> @@ -54,7 +54,7 @@
>   static void bcm2835_dma_update(BCM2835DMAState *s, unsigned c)
>   {
>       BCM2835DMAChan *ch = &s->chan[c];
> -    uint32_t data, xlen, ylen;
> +    uint32_t data, xlen, xlen_td, ylen;
>       int16_t dst_stride, src_stride;
>   
>       if (!(s->enable & (1 << c))) {
> @@ -72,13 +72,13 @@ static void bcm2835_dma_update(BCM2835DMAState *s, unsigned c)
>   
>           if (ch->ti & BCM2708_DMA_TDMODE) {
>               /* 2D transfer mode */
> -            ylen = (ch->txfr_len >> 16) & 0x3fff;
> -            xlen = ch->txfr_len & 0xffff;
> +            ylen = ((ch->txfr_len >> 16) & 0x3fff) + 1;
> +            xlen_td = xlen = ch->txfr_len & 0xffff;
>               dst_stride = ch->stride >> 16;
>               src_stride = ch->stride & 0xffff;
>           } else {
>               ylen = 1;
> -            xlen = ch->txfr_len;
> +            xlen_td = xlen = ch->txfr_len;
>               dst_stride = 0;
>               src_stride = 0;
>           }
> @@ -117,6 +117,7 @@ static void bcm2835_dma_update(BCM2835DMAState *s, unsigned c)
>               if (--ylen != 0) {
>                   ch->source_ad += src_stride;
>                   ch->dest_ad += dst_stride;
> +                xlen = xlen_td;
>               }
>           }
>           ch->cs |= BCM2708_DMA_END;
>