linux-kernel - RE: [PATCH v7 8/8] PCI: imx: Add the imx8mm pcie support

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Message-ID: <AS8PR04MB8676DC6855B91B34E441E4648C7F9@AS8PR04MB8676.eurprd04.prod.outlook.com>
Date:   Fri, 24 Dec 2021 02:09:21 +0000
From:   Hongxing Zhu <hongxing.zhu@....com>
To:     Lorenzo Pieralisi <lorenzo.pieralisi@....com>
CC:     Krzysztof Wilczyński <kw@...ux.com>,
        "l.stach@...gutronix.de" <l.stach@...gutronix.de>,
        "bhelgaas@...gle.com" <bhelgaas@...gle.com>,
        Marcel Ziswiler <marcel.ziswiler@...adex.com>,
        "tharvey@...eworks.com" <tharvey@...eworks.com>,
        "kishon@...com" <kishon@...com>,
        "vkoul@...nel.org" <vkoul@...nel.org>,
        "robh@...nel.org" <robh@...nel.org>,
        "galak@...nel.crashing.org" <galak@...nel.crashing.org>,
        "shawnguo@...nel.org" <shawnguo@...nel.org>,
        "linux-phy@...ts.infradead.org" <linux-phy@...ts.infradead.org>,
        "devicetree@...r.kernel.org" <devicetree@...r.kernel.org>,
        "linux-pci@...r.kernel.org" <linux-pci@...r.kernel.org>,
        "linux-arm-kernel@...ts.infradead.org" 
        <linux-arm-kernel@...ts.infradead.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        "kernel@...gutronix.de" <kernel@...gutronix.de>,
        dl-linux-imx <linux-imx@....com>
Subject: RE: [PATCH v7 8/8] PCI: imx: Add the imx8mm pcie support

> -----Original Message-----
> From: Lorenzo Pieralisi <lorenzo.pieralisi@....com>
> Sent: Thursday, December 23, 2021 7:50 PM
> To: Hongxing Zhu <hongxing.zhu@....com>
> Cc: Krzysztof Wilczyński <kw@...ux.com>; l.stach@...gutronix.de;
> bhelgaas@...gle.com; Marcel Ziswiler <marcel.ziswiler@...adex.com>;
> tharvey@...eworks.com; kishon@...com; vkoul@...nel.org;
> robh@...nel.org; galak@...nel.crashing.org; shawnguo@...nel.org;
> linux-phy@...ts.infradead.org; devicetree@...r.kernel.org;
> linux-pci@...r.kernel.org; linux-arm-kernel@...ts.infradead.org;
> linux-kernel@...r.kernel.org; kernel@...gutronix.de; dl-linux-imx
> <linux-imx@....com>
> Subject: Re: [PATCH v7 8/8] PCI: imx: Add the imx8mm pcie support
> 
> On Fri, Dec 17, 2021 at 05:54:21AM +0000, Hongxing Zhu wrote:
> > > -----Original Message-----
> > > From: Krzysztof Wilczyński <kw@...ux.com>
> > > Sent: Friday, December 17, 2021 12:52 AM
> > > To: Hongxing Zhu <hongxing.zhu@....com>
> > > Cc: l.stach@...gutronix.de; bhelgaas@...gle.com;
> > > lorenzo.pieralisi@....com; Marcel Ziswiler
> > > <marcel.ziswiler@...adex.com>; tharvey@...eworks.com;
> kishon@...com;
> > > vkoul@...nel.org; robh@...nel.org; galak@...nel.crashing.org;
> > > shawnguo@...nel.org; linux-phy@...ts.infradead.org;
> > > devicetree@...r.kernel.org; linux-pci@...r.kernel.org;
> > > linux-arm-kernel@...ts.infradead.org;
> > > linux-kernel@...r.kernel.org; kernel@...gutronix.de; dl-linux-imx
> > > <linux-imx@....com>
> > > Subject: Re: [PATCH v7 8/8] PCI: imx: Add the imx8mm pcie support
> > >
> > > Hi Richard,
> > >
> > > Apologies for a very late review!  Especially since Lorenzo already
> > > took patches as per:
> > >
> > >
> > >
> https://eur01.safelinks.protection.outlook.com/?url=https%3A%2F%2Flo
> > > r
> > >
> e.kernel.org%2Flinux-pci%2F163965080404.20006.52416095516435017
> > >
> 49.b4-ty%40arm.com%2F&amp;data=04%7C01%7Chongxing.zhu%40nxp
> > > .com%7C8afb673348214261883608d9c0b45b1d%7C686ea1d3bc2b4
> c6fa
> > >
> 92cd99c5c301635%7C0%7C0%7C637752703124166805%7CUnknown%7
> > >
> CTWFpbGZsb3d8eyJWIjoiMC4wLjAwMDAiLCJQIjoiV2luMzIiLCJBTiI6Ik1ha
> > >
> WwiLCJXVCI6Mn0%3D%7C3000&amp;sdata=rfmN1Xojubap2vi3J4Jol3ozy
> > > N1Q2q7YiBM5bqMm22s%3D&amp;reserved=0
> > >
> > > However, perhaps it's not too late.
> > [Richard Zhu] Hi Krzysztof:
> > Thanks for your review.
> > But I don't know how to handle this situation.
> > How about that I add this refine patch into the following bug fix and
> > refine patch-set later?
> > PCI: imx6: refine codes and add compliance tests mode support "
> >
> https://eur01.safelinks.protection.outlook.com/?url=https%3A%2F%2Fpa
> tchwork.kernel.org%2Fproject%2Flinux-arm-kernel%2Fcover%2F1635747
> 478-25562-1-git-send-email-hongxing.zhu%40nxp.com%2F&amp;data=0
> 4%7C01%7Chongxing.zhu%40nxp.com%7Ce04c6cda020b4f3849bf08d9c
> 60a5da0%7C686ea1d3bc2b4c6fa92cd99c5c301635%7C0%7C1%7C6377
> 58570100053598%7CUnknown%7CTWFpbGZsb3d8eyJWIjoiMC4wLjAwM
> DAiLCJQIjoiV2luMzIiLCJBTiI6Ik1haWwiLCJXVCI6Mn0%3D%7C2000&amp;
> sdata=joTJZcYJhmYlzSTWY%2BhGCFV5ch12HPR4mbbOwZ5vcO0%3D&a
> mp;reserved=0"
> >
> > >
> > > [...]
> > > > @@ -446,6 +452,13 @@ static int imx6_pcie_enable_ref_clk(struct
> > > imx6_pcie *imx6_pcie)
> > > >  		break;
> > > >  	case IMX7D:
> > > >  		break;
> > > > +	case IMX8MM:
> > > > +		ret = clk_prepare_enable(imx6_pcie->pcie_aux);
> > > > +		if (ret) {
> > > > +			dev_err(dev, "unable to enable pcie_aux clock\n");
> > > > +			break;
> > > > +		}
> > > > +		break;
> > >
> > > You can drop the inner break, it wouldn't do much here, unless this
> > > was intended to be a return?
> > [Richard Zhu] Yes, it is. The inner break can be dropped. The error
> > return would be handled in the end.
> >
> > >
> > > > @@ -538,6 +559,10 @@ static void
> > > imx6_pcie_deassert_core_reset(struct imx6_pcie *imx6_pcie)
> > > >  	case IMX8MQ:
> > > >  		reset_control_deassert(imx6_pcie->pciephy_reset);
> > > >  		break;
> > > > +	case IMX8MM:
> > > > +		if (phy_init(imx6_pcie->phy) != 0)
> > > > +			dev_err(dev, "Waiting for PHY ready timeout!\n");
> > > > +		break;
> > >
> > > If the above, you can keep the same style as used throughout the
> > > file already, so it would just simply be:
> > >
> > >   if (phy_init(imx6_pcie->phy))
> > >
> > > Also, a nitpick: to be consistent with other such messages here, the
> > > error message would be all lower-case letters.
> > [Richard Zhu] Yes, it is.
> > >
> > > [...]
> > > > @@ -614,6 +639,8 @@ static void imx6_pcie_configure_type(struct
> > > > imx6_pcie *imx6_pcie)  static void imx6_pcie_init_phy(struct
> > > imx6_pcie
> > > > *imx6_pcie)  {
> > > >  	switch (imx6_pcie->drvdata->variant) {
> > > > +	case IMX8MM:
> > > > +		break;
> > > >  	case IMX8MQ:
> > >
> > > Would it warrant a comment that adds a note there to this single
> > > bare break?  Perhaps this version is not support, lack this
> > > particular functionality, etc.
> > [Richard Zhu] Yes, it's easier to understand after add one comment.
> > >
> > > [...]
> > > > @@ -1089,10 +1122,39 @@ static int imx6_pcie_probe(struct
> > > platform_device *pdev)
> > > >  			dev_err(dev, "Failed to get PCIE APPS reset
> control\n");
> > > >  			return PTR_ERR(imx6_pcie->apps_reset);
> > > >  		}
> > > > +		break;
> > > > +	case IMX8MM:
> > > > +		imx6_pcie->pcie_aux = devm_clk_get(dev, "pcie_aux");
> > > > +		if (IS_ERR(imx6_pcie->pcie_aux))
> > > > +			return dev_err_probe(dev,
> > > PTR_ERR(imx6_pcie->pcie_aux),
> > > > +					     "pcie_aux clock source missing or
> > > invalid\n");
> > > > +		imx6_pcie->apps_reset =
> > > devm_reset_control_get_exclusive(dev,
> > > > +									 "apps");
> > > > +		if (IS_ERR(imx6_pcie->apps_reset)) {
> > > > +			dev_err(dev, "Failed to get PCIE APPS reset
> control\n");
> > > > +			return PTR_ERR(imx6_pcie->apps_reset);
> > > > +		}
> > > > +
> > > > +		imx6_pcie->phy = devm_phy_get(dev, "pcie-phy");
> > > > +		if (IS_ERR(imx6_pcie->phy)) {
> > > > +			if (PTR_ERR(imx6_pcie->phy) == -EPROBE_DEFER)
> > > > +				return -EPROBE_DEFER;
> > > > +			dev_err(dev, "Failed to get PCIE PHY\n");
> > > > +			return PTR_ERR(imx6_pcie->phy);
> > > > +		}
> > >
> > > A question about handling of the -EPROBE_DEFER above: why not to
> use
> > > the
> > > dev_err_probe() helper similarly to the code above and below?
> Would
> > > there be something different preventing the use of dev_err_probe()
> > > here too?
> > [Richard Zhu] To be aligned, the above one can be replaced totally.
> > I didn't want to dump the error message when -EPROBE_DEFFER
> occurs.
> > Anyway, I can make them aligned later.
> 
> Can you send me an update for this patch only so that I can update the
> corresponding commit according to this review please ?
[Richard Zhu] Sure, thanks a lot for your kindly help.

Best Regards
Richard Zhu

> 
> Thanks,
> Lorenzo
> 
> > Best Regards
> > Richard
> >
> > >
> > > >  		break;
> > > >  	default:
> > > >  		break;
> > > >  	}
> > > > +	/* Don't fetch the pcie_phy clock, if it has abstract PHY driver */
> > > > +	if (imx6_pcie->phy == NULL) {
> > > > +		imx6_pcie->pcie_phy = devm_clk_get(dev, "pcie_phy");
> > > > +		if (IS_ERR(imx6_pcie->pcie_phy))
> > > > +			return dev_err_probe(dev,
> > > PTR_ERR(imx6_pcie->pcie_phy),
> > > > +					     "pcie_phy clock source missing or
> > > invalid\n");
> > > > +	}
> > >
> > > Thank you for another amazing patch!
> > >
> > > 	Krzysztof