Re: [PATCH v2 02/10] dmaengine: imx-sdma: fix spba-bus handling for i.MX8M

[Frank Li <Frank.li@nxp.com>]

On Thu, Sep 11, 2025 at 11:56:43PM +0200, Marco Felsch wrote:
> Starting with i.MX8M* devices there are multiple spba-busses so we can't
> just search the whole DT for the first spba-bus match and take it.
> Instead we need to check for each device to which bus it belongs and
> setup the spba_{start,end}_addr accordingly per sdma_channel.
>
> While on it, don't ignore errors from of_address_to_resource() if they
> are valid.
>
> Signed-off-by: Marco Felsch <m.felsch@pengutronix.de>

I think the below method should be better.

of_translate_address(per_address) == OF_BAD_ADDR to check if belong spba-bus

aips3: bus@30800000 {
	...
        ranges = <0x30800000 0x30800000 0x400000>,
                 <0x8000000 0x8000000 0x10000000>;

                        spba1: spba-bus@30800000 {
                                compatible = "fsl,spba-bus", "simple-bus";
                                #address-cells = <1>;
                                #size-cells = <1>;
                                reg = <0x30800000 0x100000>;
                                ranges;

				...
				sdma1:

};

of_translate_address() will 1:1 map at spba-bus@30800000 spba1.
then
reach ranges = <0x30800000 0x30800000 0x400000> of aips3

if per_address is not in this range, it should return OF_BAD_ADDR. So
needn't parse reg of bus@30800000 at all.

Frank

> ---
>  drivers/dma/imx-sdma.c | 58 ++++++++++++++++++++++++++++++++++----------------
>  1 file changed, 40 insertions(+), 18 deletions(-)
>
> diff --git a/drivers/dma/imx-sdma.c b/drivers/dma/imx-sdma.c
> index 3ecb917214b1268b148a29df697b780bc462afa4..56daaeb7df03986850c9c74273d0816700581dc0 100644
> --- a/drivers/dma/imx-sdma.c
> +++ b/drivers/dma/imx-sdma.c
> @@ -429,6 +429,8 @@ struct sdma_desc {
>   * @event_mask:		event mask used in p_2_p script
>   * @watermark_level:	value for gReg[7], some script will extend it from
>   *			basic watermark such as p_2_p
> + * @spba_start_addr:	SDMA controller SPBA bus start address
> + * @spba_end_addr:	SDMA controller SPBA bus end address
>   * @shp_addr:		value for gReg[6]
>   * @per_addr:		value for gReg[2]
>   * @status:		status of dma channel
> @@ -461,6 +463,8 @@ struct sdma_channel {
>  	dma_addr_t			per_address, per_address2;
>  	unsigned long			event_mask[2];
>  	unsigned long			watermark_level;
> +	u32				spba_start_addr;
> +	u32				spba_end_addr;
>  	u32				shp_addr, per_addr;
>  	enum dma_status			status;
>  	struct imx_dma_data		data;
> @@ -534,8 +538,6 @@ struct sdma_engine {
>  	u32				script_number;
>  	struct sdma_script_start_addrs	*script_addrs;
>  	const struct sdma_driver_data	*drvdata;
> -	u32				spba_start_addr;
> -	u32				spba_end_addr;
>  	unsigned int			irq;
>  	dma_addr_t			bd0_phys;
>  	struct sdma_buffer_descriptor	*bd0;
> @@ -1236,8 +1238,6 @@ static void sdma_channel_synchronize(struct dma_chan *chan)
>
>  static void sdma_set_watermarklevel_for_p2p(struct sdma_channel *sdmac)
>  {
> -	struct sdma_engine *sdma = sdmac->sdma;
> -
>  	int lwml = sdmac->watermark_level & SDMA_WATERMARK_LEVEL_LWML;
>  	int hwml = (sdmac->watermark_level & SDMA_WATERMARK_LEVEL_HWML) >> 16;
>
> @@ -1263,12 +1263,12 @@ static void sdma_set_watermarklevel_for_p2p(struct sdma_channel *sdmac)
>  		swap(sdmac->event_mask[0], sdmac->event_mask[1]);
>  	}
>
> -	if (sdmac->per_address2 >= sdma->spba_start_addr &&
> -			sdmac->per_address2 <= sdma->spba_end_addr)
> +	if (sdmac->per_address2 >= sdmac->spba_start_addr &&
> +			sdmac->per_address2 <= sdmac->spba_end_addr)
>  		sdmac->watermark_level |= SDMA_WATERMARK_LEVEL_SP;
>
> -	if (sdmac->per_address >= sdma->spba_start_addr &&
> -			sdmac->per_address <= sdma->spba_end_addr)
> +	if (sdmac->per_address >= sdmac->spba_start_addr &&
> +			sdmac->per_address <= sdmac->spba_end_addr)
>  		sdmac->watermark_level |= SDMA_WATERMARK_LEVEL_DP;
>
>  	sdmac->watermark_level |= SDMA_WATERMARK_LEVEL_CONT;
> @@ -1447,6 +1447,31 @@ static void sdma_desc_free(struct virt_dma_desc *vd)
>  	kfree(desc);
>  }
>
> +static int sdma_config_spba_slave(struct dma_chan *chan)
> +{
> +	struct sdma_channel *sdmac = to_sdma_chan(chan);
> +	struct device_node *spba_bus;
> +	struct resource spba_res;
> +	int ret;
> +
> +	spba_bus = of_get_parent(chan->slave->of_node);
> +	/* Device doesn't belong to the spba-bus */
> +	if (!of_device_is_compatible(spba_bus, "fsl,spba-bus"))
> +		return 0;
> +
> +	ret = of_address_to_resource(spba_bus, 0, &spba_res);
> +	of_node_put(spba_bus);
> +	if (ret) {
> +		dev_err(sdmac->sdma->dev, "Failed to get spba-bus resources\n");
> +		return -EINVAL;
> +	}
> +
> +	sdmac->spba_start_addr = spba_res.start;
> +	sdmac->spba_end_addr = spba_res.end;
> +
> +	return 0;
> +}
> +
>  static int sdma_alloc_chan_resources(struct dma_chan *chan)
>  {
>  	struct sdma_channel *sdmac = to_sdma_chan(chan);
> @@ -1527,6 +1552,8 @@ static void sdma_free_chan_resources(struct dma_chan *chan)
>
>  	sdmac->event_id0 = 0;
>  	sdmac->event_id1 = 0;
> +	sdmac->spba_start_addr = 0;
> +	sdmac->spba_end_addr = 0;
>
>  	sdma_set_channel_priority(sdmac, 0);
>
> @@ -1837,6 +1864,7 @@ static int sdma_config(struct dma_chan *chan,
>  {
>  	struct sdma_channel *sdmac = to_sdma_chan(chan);
>  	struct sdma_engine *sdma = sdmac->sdma;
> +	int ret;
>
>  	memcpy(&sdmac->slave_config, dmaengine_cfg, sizeof(*dmaengine_cfg));
>
> @@ -1867,6 +1895,10 @@ static int sdma_config(struct dma_chan *chan,
>  		sdma_event_enable(sdmac, sdmac->event_id1);
>  	}
>
> +	ret = sdma_config_spba_slave(chan);
> +	if (ret)
> +		return ret;
> +
>  	return 0;
>  }
>
> @@ -2235,11 +2267,9 @@ static struct dma_chan *sdma_xlate(struct of_phandle_args *dma_spec,
>  static int sdma_probe(struct platform_device *pdev)
>  {
>  	struct device_node *np = pdev->dev.of_node;
> -	struct device_node *spba_bus;
>  	const char *fw_name;
>  	int ret;
>  	int irq;
> -	struct resource spba_res;
>  	int i;
>  	struct sdma_engine *sdma;
>  	s32 *saddr_arr;
> @@ -2375,14 +2405,6 @@ static int sdma_probe(struct platform_device *pdev)
>  			dev_err(&pdev->dev, "failed to register controller\n");
>  			goto err_register;
>  		}
> -
> -		spba_bus = of_find_compatible_node(NULL, NULL, "fsl,spba-bus");
> -		ret = of_address_to_resource(spba_bus, 0, &spba_res);
> -		if (!ret) {
> -			sdma->spba_start_addr = spba_res.start;
> -			sdma->spba_end_addr = spba_res.end;
> -		}
> -		of_node_put(spba_bus);
>  	}
>
>  	/*
>
> --
> 2.47.3
>