Re: [PATCH 01/14] dma: sun6i-dma: Add burst case of 4

Maxime Ripard
2016-10-04T16:55:54Z

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On Tue, Oct 04, 2016 at 12:40:11PM +0200, Jean-Francois Moine wrote:
> On Tue, 4 Oct 2016 11:46:14 +0200
> Mylène Josserand <mylene.josserand@free-electrons.com> wrote:
>
> > Add the case of a burst of 4 which is handled by the SoC.
> >
> > Signed-off-by: Mylène Josserand <mylene.josserand@free-electrons.com>
> > ---
> > drivers/dma/sun6i-dma.c | 2 ++
> > 1 file changed, 2 insertions(+)
> >
> > diff --git a/drivers/dma/sun6i-dma.c b/drivers/dma/sun6i-dma.c
> > index 8346199..0485204 100644
> > --- a/drivers/dma/sun6i-dma.c
> > +++ b/drivers/dma/sun6i-dma.c
> > @@ -240,6 +240,8 @@ static inline s8 convert_burst(u32 maxburst)
> > switch (maxburst) {
> > case 1:
> > return 0;
> > + case 4:
> > + return 1;
> > case 8:
> > return 2;
> > default:
> > --
> > 2.9.3
>
> This patch has already been rejected by Maxime in the threads
> http://www.spinics.net/lists/dmaengine/msg08610.html
> and
> http://www.spinics.net/lists/dmaengine/msg08719.html
>
> I hope you will find the way he wants for this maxburst to be added.

I was talking about something along these lines (not tested):

-------8<---------
diff --git a/drivers/dma/sun6i-dma.c b/drivers/dma/sun6i-dma.c
index 83461994e418..573ac4608293 100644
--- a/drivers/dma/sun6i-dma.c
+++ b/drivers/dma/sun6i-dma.c
@@ -240,6 +240,8 @@ static inline s8 convert_burst(u32 maxburst)
switch (maxburst) {
case 1:
return 0;
+ case 4:
+ return 1;
case 8:
return 2;
default:
@@ -1110,11 +1112,19 @@ static int sun6i_dma_probe(struct platform_device *pdev)
sdc->slave.dst_addr_widths = BIT(DMA_SLAVE_BUSWIDTH_1_BYTE) |
BIT(DMA_SLAVE_BUSWIDTH_2_BYTES) |
BIT(DMA_SLAVE_BUSWIDTH_4_BYTES);
+ sdc->slave.dst_bursts = BIT(1) | BIT(8);
+ sdc->slave.src_bursts = BIT(1) | BIT(8);
sdc->slave.directions = BIT(DMA_DEV_TO_MEM) |
BIT(DMA_MEM_TO_DEV);
sdc->slave.residue_granularity = DMA_RESIDUE_GRANULARITY_BURST;
sdc->slave.dev = &pdev->dev;

+ if (of_device_is_compatible(pdev->dev.of_node,
+ "allwinner,sun8i-h3-dma")) {
+ sdc->slave.dst_bursts |= BIT(4);
+ sdc->slave.src_bursts |= BIT(4);
+ }
+
sdc->pchans = devm_kcalloc(&pdev->dev, sdc->cfg->nr_max_channels,
sizeof(struct sun6i_pchan), GFP_KERNEL);
if (!sdc->pchans)
diff --git a/include/linux/dmaengine.h b/include/linux/dmaengine.h
index cc535a478bae..f7bbec24bb58 100644
--- a/include/linux/dmaengine.h
+++ b/include/linux/dmaengine.h
@@ -673,6 +673,8 @@ struct dma_filter {
* each type of direction, the dma controller should fill (1 <<
* <TYPE>) and same should be checked by controller as well
* @max_burst: max burst capability per-transfer
+ * @dst_bursts: bitfield of the available burst sizes for the destination
+ * @src_bursts: bitfield of the available burst sizes for the source
* @residue_granularity: granularity of the transfer residue reported
* by tx_status
* @device_alloc_chan_resources: allocate resources and return the
@@ -800,6 +802,14 @@ struct dma_device {
static inline int dmaengine_slave_config(struct dma_chan *chan,
struct dma_slave_config *config)
{
+ if (config->src_maxburst && config->device->src_bursts &&
+ !(BIT(config->src_maxburst) & config->device->src_bursts))
+ return -EINVAL;
+
+ if (config->dst_maxburst && config->device->dst_bursts &&
+ !(BIT(config->dst_maxburst) & config->device->dst_bursts))
+ return -EINVAL;
+
if (chan->device->device_config)
return chan->device->device_config(chan, config);
-------8<------------

Maxime

--
Maxime Ripard, Free Electrons
Embedded Linux and Kernel engineering
http://free-electrons.com

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