linux-kernel - Re: [PATCH v8 3/5] PCI: dwc: qcom: Switch to dwc ELBI resource mapping

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Message-ID: <xzzyhcuwfva6vqzmxkdqt5x7f7vxpkkyqnml6vjclb75f4ozwa@gugsrqfsbuor>
Date: Fri, 5 Sep 2025 17:13:31 +0530
From: Manivannan Sadhasivam <mani@...nel.org>
To: Bjorn Helgaas <helgaas@...nel.org>
Cc: Krishna Chaitanya Chundru <krishna.chundru@....qualcomm.com>, 
	cros-qcom-dts-watchers@...omium.org, Bjorn Andersson <andersson@...nel.org>, 
	Konrad Dybcio <konradybcio@...nel.org>, Rob Herring <robh@...nel.org>, 
	Krzysztof Kozlowski <krzk+dt@...nel.org>, Conor Dooley <conor+dt@...nel.org>, 
	Lorenzo Pieralisi <lpieralisi@...nel.org>, Krzysztof Wilczyński <kwilczynski@...nel.org>, 
	Bjorn Helgaas <bhelgaas@...gle.com>, Jingoo Han <jingoohan1@...il.com>, linux-arm-msm@...r.kernel.org, 
	devicetree@...r.kernel.org, linux-kernel@...r.kernel.org, linux-pci@...r.kernel.org, 
	quic_vbadigan@...cinc.com, quic_mrana@...cinc.com, quic_vpernami@...cinc.com, 
	mmareddy@...cinc.com, Konrad Dybcio <konrad.dybcio@....qualcomm.com>
Subject: Re: [PATCH v8 3/5] PCI: dwc: qcom: Switch to dwc ELBI resource
 mapping

On Wed, Sep 03, 2025 at 02:14:59PM GMT, Bjorn Helgaas wrote:
> On Thu, Aug 28, 2025 at 01:04:24PM +0530, Krishna Chaitanya Chundru wrote:
> > Instead of using qcom ELBI resources mapping let the DWC core map it
> > ELBI is DWC specific.
> 
> This seems like basically the same change you (Mani) added to the
> "[PATCH v8 2/5] PCI: dwc: Add support for ELBI resource mapping"
> patch?  (The patch with Mani's additions is at
> https://git.kernel.org/pub/scm/linux/kernel/git/pci/pci.git/commit/?h=controller/dwc-ecam&id=d39e0103e38f9889271a77a837b6179b42d6730d)
> 

Doh! This should've been squashed to patch 2/5 as we cannot split the conversion
patches. The reason is, we cannot ioremap() the same region twice.

This is now taken care in the branch.

- Mani

> If this qcom change is separated out, why can't the exynos and qcom-ep
> changes from patch 2/5 be separated out?  If we ever had to bisect
> and/or revert parts of this, it seems like it would be simpler to do
> them consistently like this:
> 
>   - PCI: dwc: Add ELBI resource mapping
>   - PCI: exynos: Switch to dwc ELBI resource mapping
>   - PCI: qcom: Switch to dwc ELBI resource mapping
>   - PCI: qcom-ep: Switch to dwc ELBI resource mapping
> 
> > Reviewed-by: Manivannan Sadhasivam <manivannan.sadhasivam@...aro.org>
> > Reviewed-by: Konrad Dybcio <konrad.dybcio@....qualcomm.com>
> > Signed-off-by: Krishna Chaitanya Chundru <krishna.chundru@....qualcomm.com>
> > ---
> >  drivers/pci/controller/dwc/pcie-qcom.c | 16 +++++++---------
> >  1 file changed, 7 insertions(+), 9 deletions(-)
> > 
> > diff --git a/drivers/pci/controller/dwc/pcie-qcom.c b/drivers/pci/controller/dwc/pcie-qcom.c
> > index 294babe1816e4d0c2b2343fe22d89af72afcd6cd..5092752de23866ef95036bb3f8fae9bb06e8ea1e 100644
> > --- a/drivers/pci/controller/dwc/pcie-qcom.c
> > +++ b/drivers/pci/controller/dwc/pcie-qcom.c
> > @@ -276,7 +276,6 @@ struct qcom_pcie_port {
> >  struct qcom_pcie {
> >  	struct dw_pcie *pci;
> >  	void __iomem *parf;			/* DT parf */
> > -	void __iomem *elbi;			/* DT elbi */
> >  	void __iomem *mhi;
> >  	union qcom_pcie_resources res;
> >  	struct phy *phy;
> > @@ -414,12 +413,17 @@ static void qcom_pcie_configure_dbi_atu_base(struct qcom_pcie *pcie)
> >  
> >  static void qcom_pcie_2_1_0_ltssm_enable(struct qcom_pcie *pcie)
> >  {
> > +	struct dw_pcie *pci = pcie->pci;
> >  	u32 val;
> >  
> > +	if (!pci->elbi_base) {
> > +		dev_err(pci->dev, "ELBI is not present\n");
> > +		return;
> > +	}
> >  	/* enable link training */
> > -	val = readl(pcie->elbi + ELBI_SYS_CTRL);
> > +	val = readl(pci->elbi_base + ELBI_SYS_CTRL);
> >  	val |= ELBI_SYS_CTRL_LT_ENABLE;
> > -	writel(val, pcie->elbi + ELBI_SYS_CTRL);
> > +	writel(val, pci->elbi_base + ELBI_SYS_CTRL);
> >  }
> >  
> >  static int qcom_pcie_get_resources_2_1_0(struct qcom_pcie *pcie)
> > @@ -1861,12 +1865,6 @@ static int qcom_pcie_probe(struct platform_device *pdev)
> >  		goto err_pm_runtime_put;
> >  	}
> >  
> > -	pcie->elbi = devm_platform_ioremap_resource_byname(pdev, "elbi");
> > -	if (IS_ERR(pcie->elbi)) {
> > -		ret = PTR_ERR(pcie->elbi);
> > -		goto err_pm_runtime_put;
> > -	}
> > -
> >  	/* MHI region is optional */
> >  	res = platform_get_resource_byname(pdev, IORESOURCE_MEM, "mhi");
> >  	if (res) {
> > 
> > -- 
> > 2.34.1
> > 

-- 
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