linux-kernel - Re: [PATCH v3 02/11] PCI: imx6: Fix i.MX8MP PCIe EP can not trigger MSI

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Message-ID: <Zi/DpIhGN3lAZhG0@lizhi-Precision-Tower-5810>
Date: Mon, 29 Apr 2024 11:58:28 -0400
From: Frank Li <Frank.li@....com>
To: Manivannan Sadhasivam <manivannan.sadhasivam@...aro.org>
Cc: Richard Zhu <hongxing.zhu@....com>,
	Lucas Stach <l.stach@...gutronix.de>,
	Lorenzo Pieralisi <lpieralisi@...nel.org>,
	Krzysztof Wilczyński <kw@...ux.com>,
	Rob Herring <robh@...nel.org>, Bjorn Helgaas <bhelgaas@...gle.com>,
	Shawn Guo <shawnguo@...nel.org>,
	Sascha Hauer <s.hauer@...gutronix.de>,
	Pengutronix Kernel Team <kernel@...gutronix.de>,
	Fabio Estevam <festevam@...il.com>,
	NXP Linux Team <linux-imx@....com>,
	Philipp Zabel <p.zabel@...gutronix.de>,
	Liam Girdwood <lgirdwood@...il.com>,
	Mark Brown <broonie@...nel.org>,
	Krzysztof Kozlowski <krzysztof.kozlowski+dt@...aro.org>,
	Conor Dooley <conor+dt@...nel.org>, linux-pci@...r.kernel.org,
	imx@...ts.linux.dev, linux-arm-kernel@...ts.infradead.org,
	linux-kernel@...r.kernel.org, bpf@...r.kernel.org,
	devicetree@...r.kernel.org, Jason Liu <jason.hui.liu@....com>
Subject: Re: [PATCH v3 02/11] PCI: imx6: Fix i.MX8MP PCIe EP can not trigger
 MSI

On Sat, Apr 27, 2024 at 02:53:03PM +0530, Manivannan Sadhasivam wrote:
> On Tue, Apr 02, 2024 at 10:33:38AM -0400, Frank Li wrote:
> > From: Richard Zhu <hongxing.zhu@....com>
> > 
> > Fix i.MX8MP PCIe EP can't trigger MSI issue.
> > There is one 64Kbytes minimal requirement on i.MX8M PCIe outbound
> > region configuration.
> > 
> > EP uses Bar0 to set the outboud region to configure the MSI setting.
> 
> I don't understand this statement. How EP can use BAR0 for MSI? MSIs are
> triggered using outbound window memory while BARs are mapped as inbound.
> 
> - Mani

Let's rewrite commit message. 

PCI: imx6: Fix i.MX8MP PCIe EP's occasional failure to trigger MSI

i.MX8MP PCIe EP requires 64KB alignment. MSI triggering may fail if the
outbound MSI memory region (ep->msi_mem) is not aligned to 64KB.

In dw_pcie_ep_init():

ep->msi_mem = pci_epc_mem_alloc_addr(epc, &ep->msi_mem_phys,
				     epc->mem->window.page_size);

Set ep->page_size to match drvdata::epc_features::align since different
SOCs have different alignment requirements.

Frank

> 
> > Set the page_size to "epc_features->align" to meet the requirement,
> > let the MSI can be triggered successfully.
> > 
> > Fixes: 1bd0d43dcf3b ("PCI: imx6: Clean up addr_space retrieval code")
> > Signed-off-by: Richard Zhu <hongxing.zhu@....com>
> > Acked-by: Jason Liu <jason.hui.liu@....com>
> > Signed-off-by: Frank Li <Frank.Li@....com>
> > ---
> >  drivers/pci/controller/dwc/pci-imx6.c | 2 ++
> >  1 file changed, 2 insertions(+)
> > 
> > diff --git a/drivers/pci/controller/dwc/pci-imx6.c b/drivers/pci/controller/dwc/pci-imx6.c
> > index e43eda6b33ca7..6c4d25b92225e 100644
> > --- a/drivers/pci/controller/dwc/pci-imx6.c
> > +++ b/drivers/pci/controller/dwc/pci-imx6.c
> > @@ -1118,6 +1118,8 @@ static int imx6_add_pcie_ep(struct imx6_pcie *imx6_pcie,
> >  	if (imx6_check_flag(imx6_pcie, IMX6_PCIE_FLAG_SUPPORT_64BIT))
> >  		dma_set_mask_and_coherent(dev, DMA_BIT_MASK(64));
> >  
> > +	ep->page_size = imx6_pcie->drvdata->epc_features->align;
> > +
> >  	ret = dw_pcie_ep_init(ep);
> >  	if (ret) {
> >  		dev_err(dev, "failed to initialize endpoint\n");
> > 
> > -- 
> > 2.34.1
> > 
> 
> -- 
> மணிவண்ணன் சதாசிவம்