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

From: Hongxing Zhu <hongxing.zhu@nxp.com>
To: "Krzysztof Wilczyński" <kw@linux.com>
Cc: "l.stach@pengutronix.de" <l.stach@pengutronix.de>,
	"bhelgaas@google.com" <bhelgaas@google.com>,
	"lorenzo.pieralisi@arm.com" <lorenzo.pieralisi@arm.com>,
	Marcel Ziswiler <marcel.ziswiler@toradex.com>,
	"tharvey@gateworks.com" <tharvey@gateworks.com>,
	"kishon@ti.com" <kishon@ti.com>,
	"vkoul@kernel.org" <vkoul@kernel.org>,
	"robh@kernel.org" <robh@kernel.org>,
	"galak@kernel.crashing.org" <galak@kernel.crashing.org>,
	"shawnguo@kernel.org" <shawnguo@kernel.org>,
	"linux-phy@lists.infradead.org" <linux-phy@lists.infradead.org>,
	"devicetree@vger.kernel.org" <devicetree@vger.kernel.org>,
	"linux-pci@vger.kernel.org" <linux-pci@vger.kernel.org>,
	"linux-arm-kernel@lists.infradead.org" 
	<linux-arm-kernel@lists.infradead.org>,
	"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
	"kernel@pengutronix.de" <kernel@pengutronix.de>,
	dl-linux-imx <linux-imx@nxp.com>
Subject: RE: [PATCH v7 8/8] PCI: imx: Add the imx8mm pcie support
Date: Fri, 17 Dec 2021 05:54:21 +0000	[thread overview]
Message-ID: <AS8PR04MB8676F7F8BBE79E36D3EAFB6B8C789@AS8PR04MB8676.eurprd04.prod.outlook.com> (raw)
In-Reply-To: <Ybtuo0CzfUhoJwsT@rocinante>

> -----Original Message-----
> From: Krzysztof Wilczyński <kw@linux.com>
> Sent: Friday, December 17, 2021 12:52 AM
> To: Hongxing Zhu <hongxing.zhu@nxp.com>
> Cc: l.stach@pengutronix.de; bhelgaas@google.com;
> lorenzo.pieralisi@arm.com; Marcel Ziswiler
> <marcel.ziswiler@toradex.com>; tharvey@gateworks.com;
> kishon@ti.com; vkoul@kernel.org; robh@kernel.org;
> galak@kernel.crashing.org; shawnguo@kernel.org;
> linux-phy@lists.infradead.org; devicetree@vger.kernel.org;
> linux-pci@vger.kernel.org; linux-arm-kernel@lists.infradead.org;
> linux-kernel@vger.kernel.org; kernel@pengutronix.de; dl-linux-imx
> <linux-imx@nxp.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%2Flor
> e.kernel.org%2Flinux-pci%2F163965080404.20006.52416095516435017
> 49.b4-ty%40arm.com%2F&amp;data=04%7C01%7Chongxing.zhu%40nxp
> .com%7C8afb673348214261883608d9c0b45b1d%7C686ea1d3bc2b4c6fa
> 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://patchwork.kernel.org/project/linux-arm-kernel/cover/1635747478-25562-1-git-send-email-hongxing.zhu@nxp.com/"

> 
> [...]
> > @@ -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.

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