From: Hongxing Zhu <hongxing.zhu@nxp.com> To: Lucas Stach <l.stach@pengutronix.de>, "bhelgaas@google.com" <bhelgaas@google.com>, "robh+dt@kernel.org" <robh+dt@kernel.org>, "broonie@kernel.org" <broonie@kernel.org>, "lorenzo.pieralisi@arm.com" <lorenzo.pieralisi@arm.com>, "jingoohan1@gmail.com" <jingoohan1@gmail.com>, "festevam@gmail.com" <festevam@gmail.com>, "francesco.dolcini@toradex.com" <francesco.dolcini@toradex.com> Cc: "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 v9 6/8] PCI: imx6: Disable clocks and regulators after link is down Date: Thu, 9 Jun 2022 06:17:46 +0000 [thread overview] Message-ID: <AS8PR04MB86763AE6FF5BABE3EBED833B8CA79@AS8PR04MB8676.eurprd04.prod.outlook.com> (raw) In-Reply-To: <5be4f4322e00e33fa9417280b0d74ecb7aab913e.camel@pengutronix.de> > -----Original Message----- > From: Lucas Stach <l.stach@pengutronix.de> > Sent: 2022年6月8日 15:35 > To: Hongxing Zhu <hongxing.zhu@nxp.com>; bhelgaas@google.com; > robh+dt@kernel.org; broonie@kernel.org; lorenzo.pieralisi@arm.com; > jingoohan1@gmail.com; festevam@gmail.com; > francesco.dolcini@toradex.com > Cc: 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 v9 6/8] PCI: imx6: Disable clocks and regulators after link is > down > > Am Freitag, dem 06.05.2022 um 09:47 +0800 schrieb Richard Zhu: > > Since i.MX PCIe doesn't support hot-plug, reduce power consumption as > > much as possible by disabling clocks and regulators and returning > > error when the link is down. > > > > Signed-off-by: Richard Zhu <hongxing.zhu@nxp.com> > > --- > > drivers/pci/controller/dwc/pci-imx6.c | 19 +++++++++++++++---- > > 1 file changed, 15 insertions(+), 4 deletions(-) > > > > diff --git a/drivers/pci/controller/dwc/pci-imx6.c > > b/drivers/pci/controller/dwc/pci-imx6.c > > index 3ce3993d5797..d122c12193a6 100644 > > --- a/drivers/pci/controller/dwc/pci-imx6.c > > +++ b/drivers/pci/controller/dwc/pci-imx6.c > > @@ -845,7 +845,9 @@ static int imx6_pcie_start_link(struct dw_pcie *pci) > > /* Start LTSSM. */ > > imx6_pcie_ltssm_enable(dev); > > > > - dw_pcie_wait_for_link(pci); > > + ret = dw_pcie_wait_for_link(pci); > > + if (ret) > > + goto err_out; > > This adds back error handling that has been intentionally removed in > f81f095e8771 ("PCI: imx6: Allow to probe when dw_pcie_wait_for_link() fails"). > While I agree that disabling the clocks and regulators is the right thing to do > when we don't manage to get a link, we should still allow the driver to probe, > so please add a "ret = 0" to this newly added non-fatal error paths. > Thanks for your review comments. There would be a long latency if the link is down and probe is finished successfully. Since the dw_pcie_wait_for_link() would be invoked twice in every driver probe and resume operation later. Each dw_pcie_wait_for_link() would consume about 90,000*10 ~ 100,000*10 u-seconds. I'm afraid that such a long latency would bring bad user experience. Here are the logs when probe is allowed when PCIe link is down: [ 55.045954][ T1835] imx6q-pcie 5f000000.pcie: PM: calling imx6_pcie_resume_noirq.742dfa074b40dca7ca925f0c49c905ec.cfi_jt+0x0/0x8 @ 1835, parent: bus@5f000000 ... [ 56.074566][ T1835] imx6q-pcie 5f000000.pcie: Phy link never came up [ 57.074816][ T1835] imx6q-pcie 5f000000.pcie: Phy link never came up ... [ 57.182300][ T1835] imx6q-pcie 5f000000.pcie: PM: imx6_pcie_resume_noirq.742dfa074b40dca7ca925f0c49c905ec.cfi_jt+0x0/0x8 returned 0 after 2136334 usecs [ 57.182347][ T1835] imx6q-pcie 5f010000.pcie: PM: calling imx6_pcie_resume_noirq.742dfa074b40dca7ca925f0c49c905ec.cfi_jt+0x0/0x8 @ 1835, parent: bus@5f000000 ... [ 58.210584][ T1835] imx6q-pcie 5f010000.pcie: Phy link never came up [ 59.210831][ T1835] imx6q-pcie 5f010000.pcie: Phy link never came up ... [ 59.318313][ T1835] imx6q-pcie 5f010000.pcie: PM: imx6_pcie_resume_noirq.742dfa074b40dca7ca925f0c49c905ec.cfi_jt+0x0/0x8 returned 0 after 2135949 usecs So, I'm prefer that it's better to let the probe failed when link is down. How do you think about that? > > > > if (pci->link_gen == 2) { > > /* Allow Gen2 mode after the link is up. */ @@ -876,12 +878,14 > @@ > > static int imx6_pcie_start_link(struct dw_pcie *pci) > > ret = imx6_pcie_wait_for_speed_change(imx6_pcie); > > if (ret) { > > dev_err(dev, "Failed to bring link up!\n"); > > - goto err_reset_phy; > > + goto err_out; > > } > > } > > > > /* Make sure link training is finished as well! */ > > - dw_pcie_wait_for_link(pci); > > + ret = dw_pcie_wait_for_link(pci); > > + if (ret) > > + goto err_out; > > } else { > > dev_info(dev, "Link: Gen2 disabled\n"); > > } > > @@ -890,11 +894,18 @@ static int imx6_pcie_start_link(struct dw_pcie > *pci) > > dev_info(dev, "Link up, Gen%i\n", tmp & PCI_EXP_LNKSTA_CLS); > > return 0; > > > > -err_reset_phy: > > +err_out: > > dev_dbg(dev, "PHY DEBUG_R0=0x%08x DEBUG_R1=0x%08x\n", > > dw_pcie_readl_dbi(pci, PCIE_PORT_DEBUG0), > > dw_pcie_readl_dbi(pci, PCIE_PORT_DEBUG1)); > > imx6_pcie_reset_phy(imx6_pcie); > > + imx6_pcie_clk_disable(imx6_pcie); > > + if (imx6_pcie->phy != NULL) { > > Please use the more common if (imx6_pcie->phy) here. > Okay. Thanks. Best Regards Richard Zhu > Regards, > Lucas > > > + phy_power_off(imx6_pcie->phy); > > + phy_exit(imx6_pcie->phy); > > + } > > + if (imx6_pcie->vpcie) > > + regulator_disable(imx6_pcie->vpcie); > > return ret; > > } > > >
WARNING: multiple messages have this Message-ID (diff)
From: Hongxing Zhu <hongxing.zhu@nxp.com> To: Lucas Stach <l.stach@pengutronix.de>, "bhelgaas@google.com" <bhelgaas@google.com>, "robh+dt@kernel.org" <robh+dt@kernel.org>, "broonie@kernel.org" <broonie@kernel.org>, "lorenzo.pieralisi@arm.com" <lorenzo.pieralisi@arm.com>, "jingoohan1@gmail.com" <jingoohan1@gmail.com>, "festevam@gmail.com" <festevam@gmail.com>, "francesco.dolcini@toradex.com" <francesco.dolcini@toradex.com> Cc: "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 v9 6/8] PCI: imx6: Disable clocks and regulators after link is down Date: Thu, 9 Jun 2022 06:17:46 +0000 [thread overview] Message-ID: <AS8PR04MB86763AE6FF5BABE3EBED833B8CA79@AS8PR04MB8676.eurprd04.prod.outlook.com> (raw) In-Reply-To: <5be4f4322e00e33fa9417280b0d74ecb7aab913e.camel@pengutronix.de> > -----Original Message----- > From: Lucas Stach <l.stach@pengutronix.de> > Sent: 2022年6月8日 15:35 > To: Hongxing Zhu <hongxing.zhu@nxp.com>; bhelgaas@google.com; > robh+dt@kernel.org; broonie@kernel.org; lorenzo.pieralisi@arm.com; > jingoohan1@gmail.com; festevam@gmail.com; > francesco.dolcini@toradex.com > Cc: 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 v9 6/8] PCI: imx6: Disable clocks and regulators after link is > down > > Am Freitag, dem 06.05.2022 um 09:47 +0800 schrieb Richard Zhu: > > Since i.MX PCIe doesn't support hot-plug, reduce power consumption as > > much as possible by disabling clocks and regulators and returning > > error when the link is down. > > > > Signed-off-by: Richard Zhu <hongxing.zhu@nxp.com> > > --- > > drivers/pci/controller/dwc/pci-imx6.c | 19 +++++++++++++++---- > > 1 file changed, 15 insertions(+), 4 deletions(-) > > > > diff --git a/drivers/pci/controller/dwc/pci-imx6.c > > b/drivers/pci/controller/dwc/pci-imx6.c > > index 3ce3993d5797..d122c12193a6 100644 > > --- a/drivers/pci/controller/dwc/pci-imx6.c > > +++ b/drivers/pci/controller/dwc/pci-imx6.c > > @@ -845,7 +845,9 @@ static int imx6_pcie_start_link(struct dw_pcie *pci) > > /* Start LTSSM. */ > > imx6_pcie_ltssm_enable(dev); > > > > - dw_pcie_wait_for_link(pci); > > + ret = dw_pcie_wait_for_link(pci); > > + if (ret) > > + goto err_out; > > This adds back error handling that has been intentionally removed in > f81f095e8771 ("PCI: imx6: Allow to probe when dw_pcie_wait_for_link() fails"). > While I agree that disabling the clocks and regulators is the right thing to do > when we don't manage to get a link, we should still allow the driver to probe, > so please add a "ret = 0" to this newly added non-fatal error paths. > Thanks for your review comments. There would be a long latency if the link is down and probe is finished successfully. Since the dw_pcie_wait_for_link() would be invoked twice in every driver probe and resume operation later. Each dw_pcie_wait_for_link() would consume about 90,000*10 ~ 100,000*10 u-seconds. I'm afraid that such a long latency would bring bad user experience. Here are the logs when probe is allowed when PCIe link is down: [ 55.045954][ T1835] imx6q-pcie 5f000000.pcie: PM: calling imx6_pcie_resume_noirq.742dfa074b40dca7ca925f0c49c905ec.cfi_jt+0x0/0x8 @ 1835, parent: bus@5f000000 ... [ 56.074566][ T1835] imx6q-pcie 5f000000.pcie: Phy link never came up [ 57.074816][ T1835] imx6q-pcie 5f000000.pcie: Phy link never came up ... [ 57.182300][ T1835] imx6q-pcie 5f000000.pcie: PM: imx6_pcie_resume_noirq.742dfa074b40dca7ca925f0c49c905ec.cfi_jt+0x0/0x8 returned 0 after 2136334 usecs [ 57.182347][ T1835] imx6q-pcie 5f010000.pcie: PM: calling imx6_pcie_resume_noirq.742dfa074b40dca7ca925f0c49c905ec.cfi_jt+0x0/0x8 @ 1835, parent: bus@5f000000 ... [ 58.210584][ T1835] imx6q-pcie 5f010000.pcie: Phy link never came up [ 59.210831][ T1835] imx6q-pcie 5f010000.pcie: Phy link never came up ... [ 59.318313][ T1835] imx6q-pcie 5f010000.pcie: PM: imx6_pcie_resume_noirq.742dfa074b40dca7ca925f0c49c905ec.cfi_jt+0x0/0x8 returned 0 after 2135949 usecs So, I'm prefer that it's better to let the probe failed when link is down. How do you think about that? > > > > if (pci->link_gen == 2) { > > /* Allow Gen2 mode after the link is up. */ @@ -876,12 +878,14 > @@ > > static int imx6_pcie_start_link(struct dw_pcie *pci) > > ret = imx6_pcie_wait_for_speed_change(imx6_pcie); > > if (ret) { > > dev_err(dev, "Failed to bring link up!\n"); > > - goto err_reset_phy; > > + goto err_out; > > } > > } > > > > /* Make sure link training is finished as well! */ > > - dw_pcie_wait_for_link(pci); > > + ret = dw_pcie_wait_for_link(pci); > > + if (ret) > > + goto err_out; > > } else { > > dev_info(dev, "Link: Gen2 disabled\n"); > > } > > @@ -890,11 +894,18 @@ static int imx6_pcie_start_link(struct dw_pcie > *pci) > > dev_info(dev, "Link up, Gen%i\n", tmp & PCI_EXP_LNKSTA_CLS); > > return 0; > > > > -err_reset_phy: > > +err_out: > > dev_dbg(dev, "PHY DEBUG_R0=0x%08x DEBUG_R1=0x%08x\n", > > dw_pcie_readl_dbi(pci, PCIE_PORT_DEBUG0), > > dw_pcie_readl_dbi(pci, PCIE_PORT_DEBUG1)); > > imx6_pcie_reset_phy(imx6_pcie); > > + imx6_pcie_clk_disable(imx6_pcie); > > + if (imx6_pcie->phy != NULL) { > > Please use the more common if (imx6_pcie->phy) here. > Okay. Thanks. Best Regards Richard Zhu > Regards, > Lucas > > > + phy_power_off(imx6_pcie->phy); > > + phy_exit(imx6_pcie->phy); > > + } > > + if (imx6_pcie->vpcie) > > + regulator_disable(imx6_pcie->vpcie); > > return ret; > > } > > > _______________________________________________ linux-arm-kernel mailing list linux-arm-kernel@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-arm-kernel
next prev parent reply other threads:[~2022-06-09 6:17 UTC|newest] Thread overview: 74+ messages / expand[flat|nested] mbox.gz Atom feed top 2022-05-06 1:47 [PATCH v9 0/8] PCI: imx6: refine codes and add compliance tests mode support Richard Zhu 2022-05-06 1:47 ` Richard Zhu 2022-05-06 1:47 ` [PATCH v9 1/8] PCI: imx6: Encapsulate the clock enable into one standalone function Richard Zhu 2022-05-06 1:47 ` Richard Zhu 2022-06-08 18:51 ` Bjorn Helgaas 2022-06-08 18:51 ` Bjorn Helgaas 2022-06-09 6:18 ` Hongxing Zhu 2022-06-09 6:18 ` Hongxing Zhu 2022-05-06 1:47 ` [PATCH v9 2/8] PCI: imx6: Add the error propagation from host_init Richard Zhu 2022-05-06 1:47 ` Richard Zhu 2022-06-08 18:53 ` Bjorn Helgaas 2022-06-08 18:53 ` Bjorn Helgaas 2022-06-09 6:19 ` Hongxing Zhu 2022-06-09 6:19 ` Hongxing Zhu 2022-05-06 1:47 ` [PATCH v9 3/8] PCI: imx6: Move imx6_pcie_clk_disable() earlier Richard Zhu 2022-05-06 1:47 ` Richard Zhu 2022-06-08 7:14 ` Lucas Stach 2022-06-08 7:14 ` Lucas Stach 2022-05-06 1:47 ` [PATCH v9 4/8] PCI: imx6: Disable iMX6QDL PCIe REF clock when disable PCIe clocks Richard Zhu 2022-05-06 1:47 ` Richard Zhu 2022-06-08 7:18 ` Lucas Stach 2022-06-08 7:18 ` Lucas Stach 2022-05-06 1:47 ` [PATCH v9 5/8] PCI: imx6: Refine the regulator usage Richard Zhu 2022-05-06 1:47 ` Richard Zhu 2022-06-08 7:26 ` Lucas Stach 2022-06-08 7:26 ` Lucas Stach 2022-06-09 6:17 ` Hongxing Zhu 2022-06-09 6:17 ` Hongxing Zhu 2022-06-09 7:47 ` Lucas Stach 2022-06-09 7:47 ` Lucas Stach 2022-06-09 7:54 ` Hongxing Zhu 2022-06-09 7:54 ` Hongxing Zhu 2022-06-08 18:54 ` Bjorn Helgaas 2022-06-08 18:54 ` Bjorn Helgaas 2022-06-09 6:19 ` Hongxing Zhu 2022-06-09 6:19 ` Hongxing Zhu 2022-06-09 17:20 ` Bjorn Helgaas 2022-06-09 17:20 ` Bjorn Helgaas 2022-06-10 7:09 ` Hongxing Zhu 2022-06-10 7:09 ` Hongxing Zhu 2022-05-06 1:47 ` [PATCH v9 6/8] PCI: imx6: Disable clocks and regulators after link is down Richard Zhu 2022-05-06 1:47 ` Richard Zhu 2022-06-08 7:35 ` Lucas Stach 2022-06-08 7:35 ` Lucas Stach 2022-06-09 6:17 ` Hongxing Zhu [this message] 2022-06-09 6:17 ` Hongxing Zhu 2022-06-09 7:53 ` Francesco Dolcini 2022-06-09 7:53 ` Francesco Dolcini 2022-06-09 8:36 ` Hongxing Zhu 2022-06-09 8:36 ` Hongxing Zhu 2022-06-09 7:55 ` Lucas Stach 2022-06-09 7:55 ` Lucas Stach 2022-06-09 8:30 ` Hongxing Zhu 2022-06-09 8:30 ` Hongxing Zhu 2022-05-06 1:47 ` [PATCH v9 7/8] PCI: imx6: Move the phy driver callbacks to the proper places Richard Zhu 2022-05-06 1:47 ` Richard Zhu 2022-06-08 7:44 ` Lucas Stach 2022-06-08 7:44 ` Lucas Stach 2022-06-09 6:18 ` Hongxing Zhu 2022-06-09 6:18 ` Hongxing Zhu 2022-06-08 18:57 ` Bjorn Helgaas 2022-06-08 18:57 ` Bjorn Helgaas 2022-06-09 6:20 ` Hongxing Zhu 2022-06-09 6:20 ` Hongxing Zhu 2022-06-09 16:25 ` Bjorn Helgaas 2022-06-09 16:25 ` Bjorn Helgaas 2022-06-10 6:51 ` Hongxing Zhu 2022-06-10 6:51 ` Hongxing Zhu 2022-05-06 1:47 ` [PATCH v9 8/8] PCI: imx6: Add compliance tests mode support Richard Zhu 2022-05-06 1:47 ` Richard Zhu 2022-06-08 7:48 ` Lucas Stach 2022-06-08 7:48 ` Lucas Stach 2022-06-09 6:18 ` Hongxing Zhu 2022-06-09 6:18 ` Hongxing Zhu
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