Hi Vinod,
Thanks for the feedback.
> -----Original Message-----
> From: Vinod Koul <vkoul@xxxxxxxxxx>
> Sent: Friday, March 31, 2023 1:17 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 2/3] dmaengine: sh: rz-dmac: Add device_tx_status()
> callback
>
> On 24-03-23, 09:49, Biju Das wrote:
> > The device_tx_status() callback is needed for serial DMA (RZ/G2L
> > SCIFA). Add support for device_tx_status() callback.
> >
> > Based on a patch in the BSP by Long Luu similar to rcar-dmac
> > <long.luu.ur@xxxxxxxxxxx>
> >
> > Signed-off-by: Biju Das <biju.das.jz@xxxxxxxxxxxxxx>
> > ---
> > drivers/dma/sh/rz-dmac.c | 169
> > ++++++++++++++++++++++++++++++++++++++-
> > 1 file changed, 168 insertions(+), 1 deletion(-)
> >
> > diff --git a/drivers/dma/sh/rz-dmac.c b/drivers/dma/sh/rz-dmac.c index
> > a04a37ce03fd..3625925d9f9f 100644
> > --- a/drivers/dma/sh/rz-dmac.c
> > +++ b/drivers/dma/sh/rz-dmac.c
> > @@ -110,10 +110,12 @@ struct rz_dmac {
> > * Registers
> > */
> >
> > +#define CRTB 0x0020
> > #define CHSTAT 0x0024
> > #define CHCTRL 0x0028
> > #define CHCFG 0x002c
> > #define NXLA 0x0038
> > +#define CRLA 0x003c
> >
> > #define DCTRL 0x0000
> >
> > @@ -655,6 +657,171 @@ static void rz_dmac_device_synchronize(struct
> dma_chan *chan)
> > rz_dmac_set_dmars_register(dmac, channel->index, 0); }
> >
> > +static unsigned int calculate_total_bytes_in_vd(struct rz_dmac_desc
> > +*desc) {
> > + struct scatterlist *sg, *sgl = desc->sg;
> > + unsigned int i, size, sg_len = desc->sgcount;
> > +
> > + for (i = 0, size = 0, sg = sgl; i < sg_len; i++, sg = sg_next(sg))
> > + size += sg_dma_len(sg);
>
> for_each_sg() ?
Agreed. Much simpler now.
Cheers,
Biju
>
> > +
> > + return size;
> > +}
> > +
> > +static unsigned int calculate_residue_bytes_in_vd(struct rz_dmac_chan
> > +*channel) {
> > + struct rz_lmdesc *lmdesc = channel->lmdesc.head;
> > + struct dma_chan *chan = &channel->vc.chan;
> > + struct rz_dmac *dmac = to_rz_dmac(chan->device);
> > + unsigned int residue = 0, i = 0;
> > + unsigned int crla;
> > +
> > + /* get current lmdesc */
> > + crla = rz_dmac_ch_readl(channel, CRLA, 1);
> > + while (!(lmdesc->nxla == crla)) {
> > + lmdesc++;
> > + if (lmdesc >= (channel->lmdesc.base + DMAC_NR_LMDESC))
> > + lmdesc = channel->lmdesc.base;
> > + i++;
> > + /* Not found current lmdesc */
> > + if (i > DMAC_NR_LMDESC)
> > + return 0;
> > + }
> > +
> > + /* Point to current processing lmdesc in hardware */
> > + lmdesc++;
> > + if (lmdesc >= (channel->lmdesc.base + DMAC_NR_LMDESC))
> > + lmdesc = channel->lmdesc.base;
> > +
> > + /* Calculate residue from next lmdesc to end of virtual desc*/
> > + while (lmdesc->chcfg & CHCFG_DEM) {
> > + lmdesc++;
> > + if (lmdesc >= (channel->lmdesc.base + DMAC_NR_LMDESC))
> > + lmdesc = channel->lmdesc.base;
> > + residue += lmdesc->tb;
> > + }
> > +
> > + dev_dbg(dmac->dev, "%s: Getting residue is %d\n", __func__,
> > +residue);
> > +
> > + return residue;
> > +}
> > +
> > +static unsigned int rz_dmac_chan_get_residue(struct rz_dmac_chan
> *channel,
> > + dma_cookie_t cookie)
> > +{
> > + struct rz_dmac_desc *current_desc, *desc;
> > + enum dma_status status;
> > + unsigned int residue;
> > + unsigned int crla;
> > + unsigned int crtb;
> > + unsigned int i;
> > +
> > + /* Get current processing virtual descriptor */
> > + current_desc = list_first_entry(&channel->ld_active,
> > + struct rz_dmac_desc, node);
> > + if (!current_desc)
> > + return 0;
> > +
> > + /*
> > + * If the cookie corresponds to a descriptor that has been completed
> > + * there is no residue. The same check has already been performed by
> the
> > + * caller but without holding the channel lock, so the descriptor
> could
> > + * now be complete.
> > + */
> > + status = dma_cookie_status(&channel->vc.chan, cookie, NULL);
> > + if (status == DMA_COMPLETE)
> > + return 0;
> > +
> > + /*
> > + * If the cookie doesn't correspond to the currently processing
> virtual
> > + * descriptor then the descriptor hasn't been processed yet, and the
> > + * residue is equal to the full descriptor size.
> > + * Also, a client driver is possible to call this function before
> > + * rz_dmac_irq_handler_thread() runs. In this case, the running
> > + * descriptor will be the next descriptor, and the done list will
> > + * appear. So, if the argument cookie matches the done list's cookie,
> > + * we can assume the residue is zero.
> > + */
> > + if (cookie != current_desc->vd.tx.cookie) {
> > + list_for_each_entry(desc, &channel->ld_free, node) {
> > + if (cookie == desc->vd.tx.cookie)
> > + return 0;
> > + }
> > +
> > + list_for_each_entry(desc, &channel->ld_queue, node) {
> > + if (cookie == desc->vd.tx.cookie)
> > + return calculate_total_bytes_in_vd(desc);
> > + }
> > +
> > + list_for_each_entry(desc, &channel->ld_active, node) {
> > + if (cookie == desc->vd.tx.cookie)
> > + return calculate_total_bytes_in_vd(desc);
> > + }
> > +
> > + /*
> > + * No descriptor found for the cookie, there's thus no residue.
> > + * This shouldn't happen if the calling driver passes a correct
> > + * cookie value.
> > + */
> > + WARN(1, "No descriptor for cookie!");
> > + return 0;
> > + }
> > +
> > + /*
> > + * Correspond to the currently processing virtual descriptor
> > + *
> > + * Make sure the hardware does not move to next lmdesc
> > + * while reading the counter.
> > + * Trying it 3 times should be enough: Initial read, retry, retry
> > + * for the paranoid.
> > + * The current lmdesc running in hardware is channel.lmdesc.head
> > + */
> > + for (i = 0; i < 3; i++) {
> > + crla = rz_dmac_ch_readl(channel, CRLA, 1);
> > + crtb = rz_dmac_ch_readl(channel, CRTB, 1);
> > + /* Still the same? */
> > + if (crla == rz_dmac_ch_readl(channel, CRLA, 1))
> > + break;
> > + }
> > +
> > + WARN_ONCE(i >= 3, "residue might be not continuous!");
> > +
> > + /*
> > + * Calculate number of byte transferred in processing virtual
> descriptor
> > + * One virtual descriptor can have many lmdesc
> > + */
> > + residue = crtb;
> > + residue += calculate_residue_bytes_in_vd(channel);
> > +
> > + return residue;
> > +}
> > +
> > +static enum dma_status rz_dmac_tx_status(struct dma_chan *chan,
> > + dma_cookie_t cookie,
> > + struct dma_tx_state *txstate)
> > +{
> > + struct rz_dmac_chan *channel = to_rz_dmac_chan(chan);
> > + enum dma_status status;
> > + unsigned int residue;
> > + unsigned long flags;
> > +
> > + status = dma_cookie_status(chan, cookie, txstate);
> > + if (status == DMA_COMPLETE || !txstate)
> > + return status;
> > +
> > + spin_lock_irqsave(&channel->vc.lock, flags);
> > + residue = rz_dmac_chan_get_residue(channel, cookie);
> > + spin_unlock_irqrestore(&channel->vc.lock, flags);
> > +
> > + /* if there's no residue, the cookie is complete */
> > + if (!residue)
> > + return DMA_COMPLETE;
> > +
> > + dma_set_residue(txstate, residue);
> > +
> > + return status;
> > +}
> > +
> > /*
> > * ----------------------------------------------------------------------
> -------
> > * IRQ handling
> > @@ -937,7 +1104,7 @@ static int rz_dmac_probe(struct platform_device
> > *pdev)
> >
> > engine->device_alloc_chan_resources = rz_dmac_alloc_chan_resources;
> > engine->device_free_chan_resources = rz_dmac_free_chan_resources;
> > - engine->device_tx_status = dma_cookie_status;
> > + engine->device_tx_status = rz_dmac_tx_status;
> > engine->device_prep_slave_sg = rz_dmac_prep_slave_sg;
> > engine->device_prep_dma_memcpy = rz_dmac_prep_dma_memcpy;
> > engine->device_config = rz_dmac_config;
> > --
> > 2.25.1
>
> --
> ~Vinod
