Re: [PATCH 09/12] dmaengine: dw-edma-pcie: Add register offset match flag

[Frank Li]

On Fri, May 22, 2026 at 11:57:10PM +0900, Koichiro Den wrote:
> On Thu, May 21, 2026 at 12:17:21PM -0400, Frank Li wrote:
> > On Thu, May 21, 2026 at 03:31:12PM +0900, Koichiro Den wrote:
> > > Add a match-data flag for devices whose DMA register block starts at an
> > > offset inside the mapped BAR. Existing Synopsys EDDA and AMD/Xilinx MDB
> > > matches keep using the BAR mapping base directly.
> > >
> > > No functional change intended.
> > >
> > > Signed-off-by: Koichiro Den <den@xxxxxxxxxxxxx>
> > > ---
> > >  drivers/dma/dw-edma/dw-edma-pcie.c | 3 +++
> > >  1 file changed, 3 insertions(+)
> > >
> > > diff --git a/drivers/dma/dw-edma/dw-edma-pcie.c b/drivers/dma/dw-edma/dw-edma-pcie.c
> > > index 651269708cc5..6b375a58c550 100644
> > > --- a/drivers/dma/dw-edma/dw-edma-pcie.c
> > > +++ b/drivers/dma/dw-edma/dw-edma-pcie.c
> > > @@ -88,6 +88,7 @@ struct dw_edma_pcie_match_data {
> > >
> > >  #define DW_EDMA_PCIE_F_DEVMEM_PHYS_OFF	BIT(0)
> > >  #define DW_EDMA_PCIE_F_RAW_SLAVE_ADDR	BIT(1)
> > > +#define DW_EDMA_PCIE_F_REG_OFFSET	BIT(2)
> > >
> > >  static const struct dw_edma_pcie_data snps_edda_data = {
> > >  	/* eDMA registers location */
> > > @@ -450,6 +451,8 @@ static int dw_edma_pcie_probe(struct pci_dev *pdev,
> > >  	chip->reg_base = pcim_iomap_table(pdev)[dma_data->rg.bar];
> > >  	if (!chip->reg_base)
> > >  		return -ENOMEM;
> > > +	if (match->flags & DW_EDMA_PCIE_F_REG_OFFSET)
> > > +		chip->reg_base += dma_data->rg.off;
> >
> > suppose default rg.off is 0, so needn't flag DW_EDMA_PCIE_F_REG_OFFSET.
>
> As I understand it, for the existing EDDA/MDB paths, rg.off is not applied to
> chip->reg_base. The static data has rg.off = 4K, and VSEC parsing may update it,
> but the driver still uses the BAR mapping base directly as chip->reg_base.
>
> So adding rg.off unconditionally would be a functional change for those existing
> devices. That's why I added the flag. Am I missing something?

Okay!

Reviewed-by: Frank Li <Frank.Li@xxxxxxx>
>
> Best regards,
> Koichiro
>
> >
> > Frank
> >
> > >
> > >  	for (i = 0; i < chip->ll_wr_cnt && !non_ll; i++) {
> > >  		struct dw_edma_region *ll_region = &chip->ll_region_wr[i];
> > > --
> > > 2.51.0
> > >