Re: [PATCH 08/18] dmaengine: bcm2835: pass dma_chan to generic functions

Dave Stevenson
2024-06-24T18:11:15Z

Hi Frank.

On Wed, 5 Jun 2024 at 19:05, Frank Li <Frank.li@nxp.com> wrote:
>
> On Fri, May 24, 2024 at 07:26:52PM +0100, Dave Stevenson wrote:
> > From: Stefan Wahren <stefan.wahren@i2se.com>
> >
> > In preparation to support more platforms pass the dma_chan to the
> > generic functions. This provides access to the DMA device and possible
> > platform specific data.
>
> why need this change? you can easy convert between dma_chan and
> bcm2835_chan.

These patches are leading to adding a bcm2711_chan structure for a new
(but very closely related) variant of the DMA controller.

dma_chan is the generic structure, therefore we can keep more
commonality between the variants if we use that wherever possible.

Dave

> >
> > Signed-off-by: Stefan Wahren <wahrenst@gmx.net>
> > Signed-off-by: Dave Stevenson <dave.stevenson@raspberrypi.com>
> > ---
> > drivers/dma/bcm2835-dma.c | 24 ++++++++++++++----------
> > 1 file changed, 14 insertions(+), 10 deletions(-)
> >
> > diff --git a/drivers/dma/bcm2835-dma.c b/drivers/dma/bcm2835-dma.c
> > index e2f9c8692e6b..aefaa1f01d7f 100644
> > --- a/drivers/dma/bcm2835-dma.c
> > +++ b/drivers/dma/bcm2835-dma.c
> > @@ -288,12 +288,13 @@ static void bcm2835_dma_desc_free(struct virt_dma_desc *vd)
> > }
> >
> > static bool
> > -bcm2835_dma_create_cb_set_length(struct bcm2835_chan *chan,
> > +bcm2835_dma_create_cb_set_length(struct dma_chan *chan,
> > struct bcm2835_dma_cb *control_block,
> > size_t len, size_t period_len,
> > size_t *total_len)
> > {
> > - size_t max_len = bcm2835_dma_max_frame_length(chan);
> > + struct bcm2835_chan *c = to_bcm2835_dma_chan(chan);
> > + size_t max_len = bcm2835_dma_max_frame_length(c);
> >
> > /* set the length taking lite-channel limitations into account */
> > control_block->length = min_t(u32, len, max_len);
> > @@ -417,7 +418,7 @@ static struct bcm2835_desc *bcm2835_dma_create_cb_chain(
> > /* set up length in control_block if requested */
> > if (buf_len) {
> > /* calculate length honoring period_length */
> > - if (bcm2835_dma_create_cb_set_length(c, control_block,
> > + if (bcm2835_dma_create_cb_set_length(chan, control_block,
> > len, period_len,
> > &total_len)) {
> > /* add extrainfo bits in info */
> > @@ -485,8 +486,9 @@ static void bcm2835_dma_fill_cb_chain_with_sg(
> > }
> > }
> >
> > -static void bcm2835_dma_abort(struct bcm2835_chan *c)
> > +static void bcm2835_dma_abort(struct dma_chan *chan)
> > {
> > + struct bcm2835_chan *c = to_bcm2835_dma_chan(chan);
> > void __iomem *chan_base = c->chan_base;
> > long int timeout = 10000;
> >
> > @@ -513,8 +515,9 @@ static void bcm2835_dma_abort(struct bcm2835_chan *c)
> > writel(BCM2835_DMA_RESET, chan_base + BCM2835_DMA_CS);
> > }
> >
> > -static void bcm2835_dma_start_desc(struct bcm2835_chan *c)
> > +static void bcm2835_dma_start_desc(struct dma_chan *chan)
> > {
> > + struct bcm2835_chan *c = to_bcm2835_dma_chan(chan);
> > struct virt_dma_desc *vd = vchan_next_desc(&c->vc);
> > struct bcm2835_desc *d;
> >
> > @@ -533,7 +536,8 @@ static void bcm2835_dma_start_desc(struct bcm2835_chan *c)
> >
> > static irqreturn_t bcm2835_dma_callback(int irq, void *data)
> > {
> > - struct bcm2835_chan *c = data;
> > + struct dma_chan *chan = data;
> > + struct bcm2835_chan *c = to_bcm2835_dma_chan(chan);
> > struct bcm2835_desc *d;
> > unsigned long flags;
> >
> > @@ -566,7 +570,7 @@ static irqreturn_t bcm2835_dma_callback(int irq, void *data)
> > vchan_cyclic_callback(&d->vd);
> > } else if (!readl(c->chan_base + BCM2835_DMA_ADDR)) {
> > vchan_cookie_complete(&c->desc->vd);
> > - bcm2835_dma_start_desc(c);
> > + bcm2835_dma_start_desc(chan);
> > }
> > }
> >
> > @@ -594,7 +598,7 @@ static int bcm2835_dma_alloc_chan_resources(struct dma_chan *chan)
> > }
> >
> > return request_irq(c->irq_number, bcm2835_dma_callback,
> > - c->irq_flags, "DMA IRQ", c);
> > + c->irq_flags, "DMA IRQ", chan);
> > }
> >
> > static void bcm2835_dma_free_chan_resources(struct dma_chan *chan)
> > @@ -682,7 +686,7 @@ static void bcm2835_dma_issue_pending(struct dma_chan *chan)
> >
> > spin_lock_irqsave(&c->vc.lock, flags);
> > if (vchan_issue_pending(&c->vc) && !c->desc)
> > - bcm2835_dma_start_desc(c);
> > + bcm2835_dma_start_desc(chan);
> >
> > spin_unlock_irqrestore(&c->vc.lock, flags);
> > }
> > @@ -846,7 +850,7 @@ static int bcm2835_dma_terminate_all(struct dma_chan *chan)
> > if (c->desc) {
> > vchan_terminate_vdesc(&c->desc->vd);
> > c->desc = NULL;
> > - bcm2835_dma_abort(c);
> > + bcm2835_dma_abort(chan);
> > }
> >
> > vchan_get_all_descriptors(&c->vc, &head);
> > --
> > 2.34.1
> >