On Tue, Dec 30, 2025 at 10:31:28PM +0530, Manivannan Sadhasivam wrote:
> On Fri, Dec 12, 2025 at 05:24:50PM -0500, Frank Li wrote:
> > The current descriptor layout is:
> >
> > struct dw_edma_desc *desc
> > └─ chunk list
> > └─ burst[]
> >
> > Creating a DMA descriptor requires at least two kzalloc() calls because
> > each chunk is allocated as a linked-list node. Since the number of bursts
> > is already known when the descriptor is created, this linked-list layer is
> > unnecessary.
> >
> > Move the burst array directly into struct dw_edma_desc and remove the
> > struct dw_edma_chunk layer entirely.
> >
> > Use start_burst and done_burst to track the current bursts, which current
> > are in the DMA link list.
> >
> > Signed-off-by: Frank Li <[email protected]>
> > ---
> > drivers/dma/dw-edma/dw-edma-core.c | 130
> > ++++++++++++-------------------------
> > drivers/dma/dw-edma/dw-edma-core.h | 24 ++++---
> > 2 files changed, 57 insertions(+), 97 deletions(-)
> >
>
> [...]
>
> > static struct dma_async_tx_descriptor *
> > @@ -551,8 +499,14 @@ static void dw_hdma_set_callback_result(struct
> > virt_dma_desc *vd,
> > return;
> >
> > desc = vd2dw_edma_desc(vd);
> > - if (desc)
> > - residue = desc->alloc_sz - desc->xfer_sz;
> > + residue = desc->alloc_sz;
>
> Now you dereference desc without checking for NULL.
It is impossible that desc is NULL if vd is not NULL.
static inline
struct dw_edma_desc *vd2dw_edma_desc(struct virt_dma_desc *vd)
{
return container_of(vd, struct dw_edma_desc, vd);
}
Previous check is reduntant.
Frank
>
> > +
> > + if (desc) {
> > + if (result == DMA_TRANS_NOERROR)
> > + residue -= desc->burst[desc->start_burst - 1].xfer_sz;
> > + else if (desc->done_burst)
> > + residue -= desc->burst[desc->done_burst - 1].xfer_sz;
> > + }
> >
> > res = &vd->tx_result;
> > res->result = result;
> > @@ -571,7 +525,7 @@ static void dw_edma_done_interrupt(struct dw_edma_chan
> > *chan)
> > switch (chan->request) {
> > case EDMA_REQ_NONE:
> > desc = vd2dw_edma_desc(vd);
> > - if (!desc->chunks_alloc) {
> > + if (desc->start_burst >= desc->nburst) {
> > dw_hdma_set_callback_result(vd,
> > DMA_TRANS_NOERROR);
> > list_del(&vd->node);
> > @@ -936,7 +890,7 @@ int dw_edma_probe(struct dw_edma_chip *chip)
> > goto err_irq_free;
> >
> > /* Turn debugfs on */
> > - dw_edma_core_debugfs_on(dw);
> > + //dw_edma_core_debugfs_on(dw);
>
> debug code?
Sorry, forget remove it.
Frank
>
> >
> > chip->dw = dw;
> >
> > diff --git a/drivers/dma/dw-edma/dw-edma-core.h
> > b/drivers/dma/dw-edma/dw-edma-core.h
> > index
> > 1930c3bce2bf33fdfbf4e8d99002483a4565faed..ba83c42dee5224dccdf34cec6481e9404a607702
> > 100644
> > --- a/drivers/dma/dw-edma/dw-edma-core.h
> > +++ b/drivers/dma/dw-edma/dw-edma-core.h
> > @@ -46,15 +46,8 @@ struct dw_edma_burst {
> > u64 sar;
> > u64 dar;
> > u32 sz;
> > -};
> > -
> > -struct dw_edma_chunk {
> > - struct list_head list;
> > - struct dw_edma_chan *chan;
> > - u8 cb;
> > + /* precalulate summary of previous burst total size */
> > u32 xfer_sz;
> > - u32 nburst;
> > - struct dw_edma_burst burst[] __counted_by(nburst);
> > };
> >
> > struct dw_edma_desc {
> > @@ -66,6 +59,12 @@ struct dw_edma_desc {
> >
> > u32 alloc_sz;
> > u32 xfer_sz;
> > +
> > + u32 done_burst;
> > + u32 start_burst;
> > + u8 cb;
> > + u32 nburst;
> > + struct dw_edma_burst burst[] __counted_by(nburst);
> > };
> >
> > struct dw_edma_chan {
> > @@ -126,7 +125,6 @@ struct dw_edma_core_ops {
> > void (*ll_link)(struct dw_edma_chan *chan, u32 idx, bool cb, u64 addr);
> > void (*ch_doorbell)(struct dw_edma_chan *chan);
> > void (*ch_enable)(struct dw_edma_chan *chan);
> > -
> > void (*ch_config)(struct dw_edma_chan *chan);
> > void (*debugfs_on)(struct dw_edma *dw);
> > };
> > @@ -166,6 +164,14 @@ struct dw_edma_chan *dchan2dw_edma_chan(struct
> > dma_chan *dchan)
> > return vc2dw_edma_chan(to_virt_chan(dchan));
> > }
> >
> > +static inline u64 dw_edma_core_get_ll_paddr(struct dw_edma_chan *chan)
>
> No need of inline.
>
> - Mani
>
> --
> மணிவண்ணன் சதாசிவம்
