Re: [EXT] RE: [PATCH v7 5/9] PCI: dwc: Avoid reading a register to detect whether eDMA exists

[Manivannan Sadhasivam <manivannan.sadhasivam@linaro.org>]

On Mon, Dec 12, 2022 at 07:56:00PM +0300, Serge Semin wrote:
> On Mon, Dec 12, 2022 at 06:26:58PM +0530, Manivannan Sadhasivam wrote:
> > Hi Serge,
> > 
> > On Sun, Dec 11, 2022 at 06:28:49PM +0300, Serge Semin wrote:
> > > Hi Frank
> > > 
> > > On Fri, Dec 09, 2022 at 03:52:42PM +0000, Frank Li wrote:
> > > > Hi Serge,
> > > > 
> > > > > From: Serge Semin, Sent: Thursday, December 8, 2022 11:01 PM
> > > > >
> > > > > Cc += Frank Li
> > > > >
> > > > > @Frank could you have a look at the thread and check the content of
> > > > > the CSRs dbi+0x8f8 and dbi+0x978 on available to you DW PCIe +EDMA
> > > > > devices?
> > > > 
> > > 
> > > > [    2.598038] imx6q-pcie 5f010000.pcie_ep: imx_add_pcie_ep: +0x8f8 = 3438302a, +0x978 = 00010001
> > > 
> > > Thanks for the reply. So it's 4.80a with the legacy viewport-based
> > > access. Alas it isn't what we need in this thread. We'll need
> > > @Mani's respond in order to decide how to fix the auto-detection
> > > procedure.
> > > 
> > 
> 
> > Sorry for the late reply!
> > 
> > With below diff on the EP:
> > 
> > diff --git a/drivers/pci/controller/dwc/pcie-designware.c b/drivers/pci/controller/dwc/pcie-designware.c
> > index 6f3805228a18..0eb4d3218738 100644
> > --- a/drivers/pci/controller/dwc/pcie-designware.c
> > +++ b/drivers/pci/controller/dwc/pcie-designware.c
> > @@ -665,6 +665,10 @@ static int dw_pcie_edma_find_chip(struct dw_pcie *pci)
> >         if (val == 0xFFFFFFFF && pci->edma.reg_base) {
> >                 pci->edma.mf = EDMA_MF_EDMA_UNROLL;
> >  
> > +               dev_info(pci->dev, "%s: +0x8f8 = %08x, +0x978 = %08x\n", __func__,
> > +                       dw_pcie_readl_dbi(pci, 0x8f8),
> > +                       dw_pcie_readl_dbi(pci, 0x978));
> > +
> >                 val = dw_pcie_readl_dma(pci, PCIE_DMA_CTRL);
> >         } else if (val != 0xFFFFFFFF) {
> >                 pci->edma.mf = EDMA_MF_EDMA_LEGACY;
> > 
> > 
> > The output was:
> > 
> > qcom-pcie-ep 1c08000.pcie-ep: dw_pcie_edma_find_chip: +0x8f8 = 3533302a, +0x978 = ffffffff
> > 
> > Hope this helps!
> 
> Great! Thanks. This indeed helps. So it's 5.30a IP-core. Just one
> quick question. Does that device have eDMA embedded into the DW PCIe
> controller?
> 

Yes it is and it is the test platform I use for eDMA/PCI_EP work.

Thanks,
Mani

> -Serge(y)
> 
> > 
> > Thanks,
> > Mani
> > 
> > > -Serge(y)
> > > 
> > > > 
> > > > Frank Li
> > > > 
> > > > 
> > 
> > -- 
> > மணிவண்ணன் சதாசிவம்

-- 
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