On Mon, Feb 26, 2024 at 03:53:20PM +0300, Serge Semin wrote:
> On Mon, Feb 26, 2024 at 05:07:27PM +0530, Manivannan Sadhasivam wrote:
> > In the case of Hyper DMA (HDMA) present in DWC controllers, there is no way
> > the drivers can auto detect the number of read/write channels as like its
> > predecessor embedded DMA (eDMA). So the glue drivers making use of HDMA
> > have to pass the channels count during probe.
> >
> > To accommodate that, let's skip finding the channels if the channels count
> > were already passed by glue drivers. If the channels count passed were
> > wrong in any form, then the existing sanity check will catch it.
> >
> > Suggested-by: Serge Semin <fancer.lancer@xxxxxxxxx>
> > Reviewed-by: Siddharth Vadapalli <s-vadapalli@xxxxxx>
> > Signed-off-by: Manivannan Sadhasivam <manivannan.sadhasivam@xxxxxxxxxx>
> > ---
> > drivers/pci/controller/dwc/pcie-designware.c | 16 +++++++++-------
> > 1 file changed, 9 insertions(+), 7 deletions(-)
> >
> > diff --git a/drivers/pci/controller/dwc/pcie-designware.c b/drivers/pci/controller/dwc/pcie-designware.c
> > index 193fcd86cf93..ce273c3c5421 100644
> > --- a/drivers/pci/controller/dwc/pcie-designware.c
> > +++ b/drivers/pci/controller/dwc/pcie-designware.c
> > @@ -927,13 +927,15 @@ static int dw_pcie_edma_find_channels(struct dw_pcie *pci)
> > {
> > u32 val;
> >
> > - if (pci->edma.mf == EDMA_MF_EDMA_LEGACY)
> > - val = dw_pcie_readl_dbi(pci, PCIE_DMA_VIEWPORT_BASE + PCIE_DMA_CTRL);
> > - else
> > - val = dw_pcie_readl_dma(pci, PCIE_DMA_CTRL);
> > -
> > - pci->edma.ll_wr_cnt = FIELD_GET(PCIE_DMA_NUM_WR_CHAN, val);
> > - pci->edma.ll_rd_cnt = FIELD_GET(PCIE_DMA_NUM_RD_CHAN, val);
>
> > + if (!pci->edma.ll_wr_cnt || !pci->edma.ll_rd_cnt) {
>
> Are you sure that the partly initialized case should be considered as
> a request for the auto-detection? IMO &&-ing here and letting the
> sanity check to fail further would be more correct since thus the
> developer would know about improper initialized data.
>
We already have the check below. So the partly initialized case will fail
anyway.
- Mani
> -Serge(y)
>
> > + if (pci->edma.mf == EDMA_MF_EDMA_LEGACY)
> > + val = dw_pcie_readl_dbi(pci, PCIE_DMA_VIEWPORT_BASE + PCIE_DMA_CTRL);
> > + else
> > + val = dw_pcie_readl_dma(pci, PCIE_DMA_CTRL);
> > +
> > + pci->edma.ll_wr_cnt = FIELD_GET(PCIE_DMA_NUM_WR_CHAN, val);
> > + pci->edma.ll_rd_cnt = FIELD_GET(PCIE_DMA_NUM_RD_CHAN, val);
> > + }
> >
> > /* Sanity check the channels count if the mapping was incorrect */
> > if (!pci->edma.ll_wr_cnt || pci->edma.ll_wr_cnt > EDMA_MAX_WR_CH ||
> >
> > --
> > 2.25.1
> >
--
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