linux-kernel - Re: [PATCH v3 3/5] PCI: dwc: Pass the eDMA mapping format flag directly from glue drivers

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Date: Tue, 27 Feb 2024 13:15:33 +0530
From: Manivannan Sadhasivam <manivannan.sadhasivam@...aro.org>
To: Frank Li <Frank.li@....com>
Cc: Jingoo Han <jingoohan1@...il.com>,
	Gustavo Pimentel <gustavo.pimentel@...opsys.com>,
	Lorenzo Pieralisi <lpieralisi@...nel.org>,
	Krzysztof Wilczyński <kw@...ux.com>,
	Rob Herring <robh@...nel.org>, Bjorn Helgaas <bhelgaas@...gle.com>,
	Marek Vasut <marek.vasut+renesas@...il.com>,
	Yoshihiro Shimoda <yoshihiro.shimoda.uh@...esas.com>,
	Kishon Vijay Abraham I <kishon@...nel.org>,
	Serge Semin <fancer.lancer@...il.com>, linux-pci@...r.kernel.org,
	linux-kernel@...r.kernel.org, linux-renesas-soc@...r.kernel.org,
	linux-arm-msm@...r.kernel.org, mhi@...ts.linux.dev,
	Siddharth Vadapalli <s-vadapalli@...com>
Subject: Re: [PATCH v3 3/5] PCI: dwc: Pass the eDMA mapping format flag
 directly from glue drivers

On Mon, Feb 26, 2024 at 11:30:13AM -0500, Frank Li wrote:
> On Mon, Feb 26, 2024 at 05:07:28PM +0530, Manivannan Sadhasivam wrote:
> > Instead of maintaining a separate capability for glue drivers that cannot
> > support auto detection of the eDMA mapping format, let's pass the mapping
> > format directly from them.
> 
> Sorry, what's mapping? is it register address layout?
> 

Memory map containing the register layout for iATU, DMA etc...

- Mani

> Frank
> 
> > 
> > This will simplify the code and also allow adding HDMA support that also
> > doesn't support auto detection of mapping format.
> > 
> > Suggested-by: Serge Semin <fancer.lancer@...il.com>
> > Reviewed-by: Siddharth Vadapalli <s-vadapalli@...com>
> > Signed-off-by: Manivannan Sadhasivam <manivannan.sadhasivam@...aro.org>
> > ---
> >  drivers/pci/controller/dwc/pcie-designware.c | 16 +++++++++-------
> >  drivers/pci/controller/dwc/pcie-designware.h |  5 ++---
> >  drivers/pci/controller/dwc/pcie-rcar-gen4.c  |  2 +-
> >  3 files changed, 12 insertions(+), 11 deletions(-)
> > 
> > diff --git a/drivers/pci/controller/dwc/pcie-designware.c b/drivers/pci/controller/dwc/pcie-designware.c
> > index ce273c3c5421..3e90b9947a13 100644
> > --- a/drivers/pci/controller/dwc/pcie-designware.c
> > +++ b/drivers/pci/controller/dwc/pcie-designware.c
> > @@ -894,18 +894,20 @@ static int dw_pcie_edma_find_mf(struct dw_pcie *pci)
> >  {
> >  	u32 val;
> >  
> > +	/*
> > +	 * Bail out finding the mapping format if it is already set by the glue
> > +	 * driver. Also ensure that the edma.reg_base is pointing to a valid
> > +	 * memory region.
> > +	 */
> > +	if (pci->edma.mf != EDMA_MF_EDMA_LEGACY)
> > +		return pci->edma.reg_base ? 0 : -ENODEV;
> > +
> >  	/*
> >  	 * Indirect eDMA CSRs access has been completely removed since v5.40a
> >  	 * thus no space is now reserved for the eDMA channels viewport and
> >  	 * former DMA CTRL register is no longer fixed to FFs.
> > -	 *
> > -	 * Note that Renesas R-Car S4-8's PCIe controllers for unknown reason
> > -	 * have zeros in the eDMA CTRL register even though the HW-manual
> > -	 * explicitly states there must FFs if the unrolled mapping is enabled.
> > -	 * For such cases the low-level drivers are supposed to manually
> > -	 * activate the unrolled mapping to bypass the auto-detection procedure.
> >  	 */
> > -	if (dw_pcie_ver_is_ge(pci, 540A) || dw_pcie_cap_is(pci, EDMA_UNROLL))
> > +	if (dw_pcie_ver_is_ge(pci, 540A))
> >  		val = 0xFFFFFFFF;
> >  	else
> >  		val = dw_pcie_readl_dbi(pci, PCIE_DMA_VIEWPORT_BASE + PCIE_DMA_CTRL);
> > diff --git a/drivers/pci/controller/dwc/pcie-designware.h b/drivers/pci/controller/dwc/pcie-designware.h
> > index 26dae4837462..995805279021 100644
> > --- a/drivers/pci/controller/dwc/pcie-designware.h
> > +++ b/drivers/pci/controller/dwc/pcie-designware.h
> > @@ -51,9 +51,8 @@
> >  
> >  /* DWC PCIe controller capabilities */
> >  #define DW_PCIE_CAP_REQ_RES		0
> > -#define DW_PCIE_CAP_EDMA_UNROLL		1
> > -#define DW_PCIE_CAP_IATU_UNROLL		2
> > -#define DW_PCIE_CAP_CDM_CHECK		3
> > +#define DW_PCIE_CAP_IATU_UNROLL		1
> > +#define DW_PCIE_CAP_CDM_CHECK		2
> >  
> >  #define dw_pcie_cap_is(_pci, _cap) \
> >  	test_bit(DW_PCIE_CAP_ ## _cap, &(_pci)->caps)
> > diff --git a/drivers/pci/controller/dwc/pcie-rcar-gen4.c b/drivers/pci/controller/dwc/pcie-rcar-gen4.c
> > index e9166619b1f9..3c535ef5ea91 100644
> > --- a/drivers/pci/controller/dwc/pcie-rcar-gen4.c
> > +++ b/drivers/pci/controller/dwc/pcie-rcar-gen4.c
> > @@ -255,7 +255,7 @@ static struct rcar_gen4_pcie *rcar_gen4_pcie_alloc(struct platform_device *pdev)
> >  	rcar->dw.ops = &dw_pcie_ops;
> >  	rcar->dw.dev = dev;
> >  	rcar->pdev = pdev;
> > -	dw_pcie_cap_set(&rcar->dw, EDMA_UNROLL);
> > +	rcar->dw.edma.mf = EDMA_MF_EDMA_UNROLL;
> >  	dw_pcie_cap_set(&rcar->dw, REQ_RES);
> >  	platform_set_drvdata(pdev, rcar);
> >  
> > 
> > -- 
> > 2.25.1
> > 

-- 
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