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

Hongxing Zhu
2021-12-17T05:54:25Z

> -----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