Hi Vinod,
> Subject: RE: [PATCH 1/3] dmaengine: sh: rz-dmac: Reinitialize lmdescriptor
> head
>
> Hi Vinod,
>
> Thanks for the feedback.
>
> > -----Original Message-----
> > From: Vinod Koul <vkoul@xxxxxxxxxx>
> > Sent: Friday, March 31, 2023 1:15 PM
> > To: Biju Das <biju.das.jz@xxxxxxxxxxxxxx>
> > Cc: Prabhakar Mahadev Lad <prabhakar.mahadev-lad.rj@xxxxxxxxxxxxxx>;
> > Geert Uytterhoeven <geert+renesas@xxxxxxxxx>;
> > dmaengine@xxxxxxxxxxxxxxx; linux- renesas-soc@xxxxxxxxxxxxxxx
> > Subject: Re: [PATCH 1/3] dmaengine: sh: rz-dmac: Reinitialize
> > lmdescriptor head
> >
> > On 24-03-23, 09:49, Biju Das wrote:
> > > Reinitialize link mode descriptor head during terminate_all().
> > > It fixes the incorrect serial messages during serial transfer when
> > > DMA is enabled.
> > >
> > > Based on a patch in the BSP by Long Luu <long.luu.ur@xxxxxxxxxxx>
> > >
> > > Signed-off-by: Biju Das <biju.das.jz@xxxxxxxxxxxxxx>
> > > ---
> > > drivers/dma/sh/rz-dmac.c | 7 +++++++
> > > 1 file changed, 7 insertions(+)
> > >
> > > diff --git a/drivers/dma/sh/rz-dmac.c b/drivers/dma/sh/rz-dmac.c
> > > index 6b62e01ba658..a04a37ce03fd 100644
> > > --- a/drivers/dma/sh/rz-dmac.c
> > > +++ b/drivers/dma/sh/rz-dmac.c
> > > @@ -534,11 +534,18 @@ rz_dmac_prep_slave_sg(struct dma_chan *chan,
> > > struct scatterlist *sgl, static int rz_dmac_terminate_all(struct
> > > dma_chan *chan) {
> > > struct rz_dmac_chan *channel = to_rz_dmac_chan(chan);
> > > + struct rz_lmdesc *lmdesc = channel->lmdesc.base;
> > > unsigned long flags;
> > > + unsigned int i;
> > > +
> > > LIST_HEAD(head);
> > >
> > > rz_dmac_disable_hw(channel);
> > > spin_lock_irqsave(&channel->vc.lock, flags);
> > > +
> > > + for (i = 0; i < DMAC_NR_LMDESC; i++)
> > > + lmdesc[i].header = 0;
> >
I will send an improved version for invalidating lmdesc.
Add helper function rz_dmac_invalidate_lmdesc() and share the code between
rz_dmac_free_chan_resources and rz_dmac_terminate_all(),so that hardware
descriptors can be reused in rz_dmac_lmdesc_recycle().
+static void rz_dmac_invalidate_lmdesc(struct rz_dmac_chan *channel)
+{
+ struct rz_lmdesc *lmdesc = channel->lmdesc.base;
+
+ for (; lmdesc < channel->lmdesc.base + DMAC_NR_LMDESC; lmdesc++) {
+ if (lmdesc->header)
+ lmdesc->header = 0;
+ }
+}
+
static void rz_dmac_lmdesc_recycle(struct rz_dmac_chan *channel)
{
struct rz_lmdesc *lmdesc = channel->lmdesc.head;
@@ -437,16 +447,11 @@ static void rz_dmac_free_chan_resources(struct dma_chan *chan)
{
struct rz_dmac_chan *channel = to_rz_dmac_chan(chan);
struct rz_dmac *dmac = to_rz_dmac(chan->device);
- struct rz_lmdesc *lmdesc = channel->lmdesc.base;
struct rz_dmac_desc *desc, *_desc;
unsigned long flags;
- unsigned int i;
spin_lock_irqsave(&channel->vc.lock, flags);
-
- for (i = 0; i < DMAC_NR_LMDESC; i++)
- lmdesc[i].header = 0;
-
+ rz_dmac_invalidate_lmdesc(channel);
rz_dmac_disable_hw(channel);
list_splice_tail_init(&channel->ld_active, &channel->ld_free);
list_splice_tail_init(&channel->ld_queue, &channel->ld_free);
@@ -537,6 +542,7 @@ static int rz_dmac_terminate_all(struct dma_chan *chan)
rz_dmac_disable_hw(channel);
spin_lock_irqsave(&channel->vc.lock, flags);
+ rz_dmac_invalidate_lmdesc(channel);
