Re: [PATCH v4 4/5] dma: imx-sdma: add a test for imx8mq multi sdma devices

[Lucas Stach]

Am Donnerstag, den 24.01.2019, 19:55 -0700 schrieb Angus Ainslie (Purism):
> On i.mx8mq, there are two sdma instances, and the common dma framework
> will get a channel dynamically from any available sdma instance whether
> it's the first sdma device or the second sdma device. Some IPs like
> SAI only work with sdma2 not sdma1. To make sure the sdma channel is from
> the correct sdma device, use the phandle to match.
> 
> > Signed-off-by: Angus Ainslie (Purism) <angus@xxxxxxxx>
> ---
> Âdrivers/dma/imx-sdma.cÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂ| 8 ++++++++
> Âinclude/linux/platform_data/dma-imx.h | 1 +
> Â2 files changed, 9 insertions(+)
> 
> diff --git a/drivers/dma/imx-sdma.c b/drivers/dma/imx-sdma.c
> index ec6fb48f387a..88e112a4aabf 100644
> --- a/drivers/dma/imx-sdma.c
> +++ b/drivers/dma/imx-sdma.c
> @@ -1927,11 +1927,17 @@ static int sdma_init(struct sdma_engine *sdma)
> Âstatic bool sdma_filter_fn(struct dma_chan *chan, void *fn_param)
> Â{
> > Â	struct sdma_channel *sdmac = to_sdma_chan(chan);
> > +	struct sdma_engine *sdma = sdmac->sdma;
> > Â	struct imx_dma_data *data = fn_param;
> Â
> > Â	if (!imx_dma_is_general_purpose(chan))
> > Â		return false;
> Â
> > +	/* return false if it's not the right device */
> +	if ((sdmac->sdma->drvdata == &sdma_imx8mq)

Why do this check only on i.MX8M? This is completely generic and can
and shouldÂbe done for every SDMA engine with a OF node.

Also why use the phandle to match this instead of the of_node pointer
directly?

Regards,
Lucas

> +		&& (sdma->dev->of_node->phandle != data->phandle))
> > +		return false;
> +
> > Â	sdmac->data = *data;
> > Â	chan->private = &sdmac->data;
> Â
> @@ -1942,6 +1948,7 @@ static struct dma_chan *sdma_xlate(struct of_phandle_args *dma_spec,
> > Â				ÂÂÂstruct of_dma *ofdma)
> Â{
> > Â	struct sdma_engine *sdma = ofdma->of_dma_data;
> > +	struct device_node *np = ofdma->of_node;
> > Â	dma_cap_mask_t mask = sdma->dma_device.cap_mask;
> > Â	struct imx_dma_data data;
> Â
> @@ -1959,6 +1966,7 @@ static struct dma_chan *sdma_xlate(struct of_phandle_args *dma_spec,
> > Â	Â* be set to sdmac->event_id1.
> > Â	Â*/
> > Â	data.dma_request2 = 0;
> > +	data.phandle = np->phandle;
> Â
> > Â	return dma_request_channel(mask, sdma_filter_fn, &data);
> Â}
> diff --git a/include/linux/platform_data/dma-imx.h b/include/linux/platform_data/dma-imx.h
> index 7d964e787299..eeb5b73ae542 100644
> --- a/include/linux/platform_data/dma-imx.h
> +++ b/include/linux/platform_data/dma-imx.h
> @@ -55,6 +55,7 @@ struct imx_dma_data {
> > Â	int dma_request2; /* secondary DMA request line */
> > Â	enum sdma_peripheral_type peripheral_type;
> > Â	int priority;
> > +	int phandle;
> Â};
> Â
> Âstatic inline int imx_dma_is_ipu(struct dma_chan *chan)