Hi Laurent Pinchart,
Thanks for the review...
> > + int i = 0, j = 0;
> >
> > if (chan->desc_submitcount < chan->num_frms)
> > i = chan->desc_submitcount;
>
> I don't get this. i seems to index into a segment start address array, but gets
> initialized with a variable documented as "Descriptor h/w submitted count". I'm
> not familiar with the hardware, but it makes no sense to me.
Here i is the h/w buffer address.
For ex: If the h/w is configured for 3 frame buffers and user submits 4 desc's
Then we need to submit only 3 frame buffers to the h/w and the next desc will be submitted
After there is a room for buffers I mean when the free buffer is available.
>
> > - list_for_each_entry(segment, &desc->segments, node) {
> > - if (chan->ext_addr)
> > - vdma_desc_write_64(chan,
> > -
> XILINX_VDMA_REG_START_ADDRESS_64(i++),
> > - segment->hw.buf_addr,
> > - segment->hw.buf_addr_msb);
> > - else
> > - vdma_desc_write(chan,
> > -
> XILINX_VDMA_REG_START_ADDRESS(i++),
> > - segment->hw.buf_addr);
> > -
> > - last = segment;
>
> Isn't it an issue to write the descriptors only after calling
> xilinx_dma_start() ?
Until writing to the VSIZE h/w won't get started...
>
> > + for (j = 0; j < chan->num_frms; ) {
> > + list_for_each_entry(segment, &desc->segments, node)
> {
> > + if (chan->ext_addr)
> > + vdma_desc_write_64(chan,
> > +
> XILINX_VDMA_REG_START_ADDRESS_64(i++),
> > + segment->hw.buf_addr,
> > + segment->hw.buf_addr_msb);
> > + else
> > + vdma_desc_write(chan,
> > +
> XILINX_VDMA_REG_START_ADDRESS(i++),
> > + segment->hw.buf_addr);
>
> I assume the size of the start address array to be limited by the hardware, but I
> don't see how this code prevents from overflowing this.
>
> The whole function is very difficult to understand, it probably requires a rewrite.
Will fix it in v2...
>
> > + last = segment;
> > + }
> > + list_del(&desc->node);
> > + list_add_tail(&desc->node, &chan->active_list);
> > + j++;
> > + if (list_empty(&chan->pending_list))
> > + break;
> > + desc = list_first_entry(&chan->pending_list,
> > + struct
> xilinx_dma_tx_descriptor,
> > + node);
> > }
> > if (!chan->has_sg) {
> > - list_del(&desc->node);
> > - list_add_tail(&desc->node, &chan->active_list);
> > - chan->desc_submitcount++;
> > - chan->desc_pendingcount--;
> > if (chan->desc_submitcount == chan->num_frms)
> > chan->desc_submitcount = 0;
> > } else {
>
> While at it, can you merge this into the previous if (chan->has_sg) { ... } else { ... }
> ? Having them separate is confusing.
Ok sure will fix in v2...
Regards,
Kedar.
>
>
> --
> Regards,
>
> Laurent Pinchart
--
To unsubscribe from this list: send the line "unsubscribe dmaengine" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at http://vger.kernel.org/majordomo-info.html
