Re: [PATCH v2 3/3] misc: fastrpc: Update dma_mask for CDSP support on Kaanapali SoC

[Kumari Pallavi]

On 10/15/2025 2:55 PM, Srinivas Kandagatla wrote:
> On 10/15/25 5:57 AM, Kumari Pallavi wrote:
> > DSP currently supports 32-bit IOVA (32-bit PA + 4-bit SID) for
> > both Q6 and user DMA (uDMA) access. This is being upgraded to
> > 34-bit PA + 4-bit SID due to a hardware revision in CDSP for
> > Kaanapali SoC, which expands the DMA addressable range.
> > Update DMA mask configuration in the driver to support CDSP on
> > Kaanapali SoC. Set the default `dma_mask` to 32-bit and update
> > it to 34-bit based on CDSP and SoC-specific compatible string.
> >
> > Signed-off-by: Kumari Pallavi <kumari.pallavi@xxxxxxxxxxxxxxxx>
> > ---
> >   drivers/misc/fastrpc.c | 9 +++++++--
> >   1 file changed, 7 insertions(+), 2 deletions(-)
> >
> > diff --git a/drivers/misc/fastrpc.c b/drivers/misc/fastrpc.c
> > index 1a5d620b23f2..f2e5e53e9067 100644
> > --- a/drivers/misc/fastrpc.c
> > +++ b/drivers/misc/fastrpc.c
> > @@ -267,6 +267,7 @@ struct fastrpc_session_ctx {
> >   
> >   struct fastrpc_soc_data {
> >   	u32 sid_pos;
> > +	u32 cdsp_dma_mask;
> How about making this an actual dmamask ex:
>
> 	u64 cdsp_dma_mask == DMA_BIT_MASK(64),
> 	u64 dma_mask == DMA_BIT_MASK(32),
>
> This will give more clear picture of what is going on,

The current approach of assigning a value to cdsp_dma_mask allows for 
adaptable logging behavior, making it easier to trace.

> BTW, these values are not set in the patch for some reason for both
> default and soc specific soc data>

Ack.

> >   struct fastrpc_channel_ctx {
> > @@ -2178,6 +2179,7 @@ static int fastrpc_cb_probe(struct platform_device *pdev)
> >   	int i, sessions = 0;
> >   	unsigned long flags;
> >   	int rc;
> > +	u32 dma_mask = 32;this should come from default soc_data, do not hardcode this here.
> 	u64 dma_mask = default_soc_data->dma_mask;>

Ack.

> >   	cctx = dev_get_drvdata(dev->parent);
> >   	if (!cctx)
> > @@ -2197,6 +2199,9 @@ static int fastrpc_cb_probe(struct platform_device *pdev)
> >   	sess->dev = dev;
> >   	dev_set_drvdata(dev, sess);> +	if (cctx->domain_id == CDSP_DOMAIN_ID)
> > +		dma_mask = cctx->soc_data->cdsp_dma_mask;
> > +
>
> >   	if (of_property_read_u32(dev->of_node, "reg", &sess->sid))
> >   		dev_info(dev, "FastRPC Session ID not specified in DT\n");
> >   
> > @@ -2211,9 +2216,9 @@ static int fastrpc_cb_probe(struct platform_device *pdev)
> >   		}
> >   	}
> >   	spin_unlock_irqrestore(&cctx->lock, flags);
> > -	rc = dma_set_mask(dev, DMA_BIT_MASK(32));
> > +	rc = dma_set_mask(dev, DMA_BIT_MASK(dma_mask));
> >   	if (rc) {
> > -		dev_err(dev, "32-bit DMA enable failed\n");
> > +		dev_err(dev, "%u-bit DMA enable failed\n", dma_mask);
> >   		return rc;
> >   	}
> >