RE: [PATCH v3 11/15] dmaengine: sh: rz-dmac: Add cyclic DMA support

[Biju Das <biju.das.jz@bp.renesas.com>]

Hi Claudiu Beznea,

> -----Original Message-----
> From: Claudiu Beznea <claudiu.beznea@tuxon.dev>
> Sent: 07 April 2026 16:13
> Subject: Re: [PATCH v3 11/15] dmaengine: sh: rz-dmac: Add cyclic DMA support
> 
> Hi, Biju,
> 
> On 4/7/26 17:36, Biju Das wrote:
> >
> > Hi Claudiu,
> >
> > Thanks for the patch.
> >
> >> -----Original Message-----
> >> From: Claudiu <claudiu.beznea@tuxon.dev>
> >> Sent: 07 April 2026 14:35
> >> Subject: [PATCH v3 11/15] dmaengine: sh: rz-dmac: Add cyclic DMA
> >> support
> >>
> >> From: Claudiu Beznea <claudiu.beznea.uj@bp.renesas.com>
> >>
> >> Add cyclic DMA support to the RZ DMAC driver. A per-channel status
> >> bit is introduced to mark cyclic channels and is set during the DMA
> >> prepare callback. The IRQ handler checks this status bit and calls
> >> vchan_cyclic_callback() accordingly.
> >>
> >> Signed-off-by: Claudiu Beznea <claudiu.beznea.uj@bp.renesas.com>
> >> ---
> >>
> >> Changes in v3:
> >> - updated rz_dmac_lmdesc_recycle() to restore the lmdesc->nxla
> >> - in rz_dmac_prepare_descs_for_cyclic() update directly the
> >>    desc->start_lmdesc with the descriptor pointer insted of the
> >>    descriptor address
> >> - used rz_dmac_lmdesc_addr() to compute the descritor address
> >> - set channel->status = 0 in rz_dmac_free_chan_resources()
> >> - in rz_dmac_prep_dma_cyclic() check for invalid periods or buffer len
> >>    and limit the critical area protected by spinlock
> >> - set channel->status = 0 in rz_dmac_terminate_all()
> >> - updated rz_dmac_calculate_residue_bytes_in_vd() to use
> >>    rz_dmac_lmdesc_addr()
> >> - dropped goto in rz_dmac_irq_handler_thread() as it is not needed
> >>    anymore; dropped also the local variable desc
> >>
> >> Changes in v2:
> >> - none
> >>
> >>   drivers/dma/sh/rz-dmac.c | 144 +++++++++++++++++++++++++++++++++++++--
> >>   1 file changed, 138 insertions(+), 6 deletions(-)
> >>
> 
> [ ... ]
> 
> >> @@ -500,6 +562,8 @@ static void rz_dmac_free_chan_resources(struct dma_chan *chan)
> >>   		channel->mid_rid = -EINVAL;
> >>   	}
> >>
> >> +	channel->status = 0;
> >> +
> >>   	spin_unlock_irqrestore(&channel->vc.lock, flags);
> >
> > Maybe create a patch to convert all the spin_{lock,unlock} with
> > guard() in this driver.
> 
> This series already has to many patches and I want to keep only what is necessary for the cyclic
> support. My plan is to do the guard conversion after cyclic support gets merged.

The driver has a mix of guard and spin_lock_unlock variants with this series.
That is the reason for suggestion.

Yes, it can be done later.

Cheers,
Biju