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[34.82.65.13]) by smtp.gmail.com with ESMTPSA id g15-20020a63f40f000000b0053031f7a367sm7019460pgi.85.2023.05.12.10.00.34 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Fri, 12 May 2023 10:00:34 -0700 (PDT) Date: Fri, 12 May 2023 10:00:30 -0700 From: William McVicker To: Lorenzo Pieralisi Cc: Bjorn Helgaas , Lorenzo Pieralisi , Jingoo Han , Gustavo Pimentel , Krzysztof =?utf-8?Q?Wilczy=C5=84ski?= , Rob Herring , Nikhil Devshatwar , Manu Gautam , Bjorn Helgaas , Sajid Dalvi , linux-pci@vger.kernel.org, Ajay Agarwal Subject: Re: [PATCH v4] PCI: dwc: Wait for link up only if link is started Message-ID: References: <20230425190724.GA59133@bhelgaas> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: X-ccpol: medium Precedence: bulk List-ID: X-Mailing-List: linux-pci@vger.kernel.org On 05/08/2023, Ajay Agarwal wrote: > Sure, understood. Thanks Bjorn for the explanation. > If v6.4-rc1 is tagged by now, please consider applying this patch to the > main branch. > > -Ajay > > On Wed, Apr 26, 2023 at 12:37 AM Bjorn Helgaas wrote: > > > On Tue, Apr 25, 2023 at 11:44:59PM +0530, Ajay Agarwal wrote: > > > Thanks for the review and testing the patch William! > > > > > > Hi Lorenzo > > > Can you please include this patch in the next release if it looks good? > > > > Just to set expectations, the v6.4 merge window is open now, so we'll > > be asking Linus to pull everything that has already been merged. > > v6.4-rc1 should be tagged May 7, and then we'll start applying patches > > (like this one) that are destined for v6.5. > > > > Bjorn > > > > > On Thu, Apr 20, 2023 at 12:59 AM William McVicker > > > wrote: > > > > > > > > On 04/12/2023, Ajay Agarwal wrote: > > > > > In dw_pcie_host_init() regardless of whether the link has been > > > > > started or not, the code waits for the link to come up. Even in > > > > > cases where start_link() is not defined the code ends up spinning > > > > > in a loop for 1 second. Since in some systems dw_pcie_host_init() > > > > > gets called during probe, this one second loop for each pcie > > > > > interface instance ends up extending the boot time. > > > > > > > > > > Wait for the link up in only if the start_link() is defined. > > > > > > > > > > Signed-off-by: Sajid Dalvi > > > > > Signed-off-by: Ajay Agarwal > > > > > --- > > > > > Changelog since v3: > > > > > - Run dw_pcie_start_link() only if link is not already up > > > > > > > > > > Changelog since v2: > > > > > - Wait for the link up if start_link() is really defined. > > > > > - Print the link status if the link is up on init. > > > > > > > > > > .../pci/controller/dwc/pcie-designware-host.c | 13 ++++++++---- > > > > > drivers/pci/controller/dwc/pcie-designware.c | 20 > > ++++++++++++------- > > > > > drivers/pci/controller/dwc/pcie-designware.h | 1 + > > > > > 3 files changed, 23 insertions(+), 11 deletions(-) > > > > > > > > > > diff --git a/drivers/pci/controller/dwc/pcie-designware-host.c > > b/drivers/pci/controller/dwc/pcie-designware-host.c > > > > > index 9952057c8819..cf61733bf78d 100644 > > > > > --- a/drivers/pci/controller/dwc/pcie-designware-host.c > > > > > +++ b/drivers/pci/controller/dwc/pcie-designware-host.c > > > > > @@ -485,14 +485,19 @@ int dw_pcie_host_init(struct dw_pcie_rp *pp) > > > > > if (ret) > > > > > goto err_remove_edma; > > > > > > > > > > - if (!dw_pcie_link_up(pci)) { > > > > > + if (dw_pcie_link_up(pci)) { > > > > > + dw_pcie_print_link_status(pci); > > > > > + } else { > > > > > ret = dw_pcie_start_link(pci); > > > > > if (ret) > > > > > goto err_remove_edma; > > > > > - } > > > > > > > > > > - /* Ignore errors, the link may come up later */ > > > > > - dw_pcie_wait_for_link(pci); > > > > > + if (pci->ops && pci->ops->start_link) { > > > > > + ret = dw_pcie_wait_for_link(pci); > > > > > + if (ret) > > > > > + goto err_stop_link; > > > > > + } > > > > > + } > > > > > > > > > > bridge->sysdata = pp; > > > > > > > > > > diff --git a/drivers/pci/controller/dwc/pcie-designware.c > > b/drivers/pci/controller/dwc/pcie-designware.c > > > > > index 53a16b8b6ac2..03748a8dffd3 100644 > > > > > --- a/drivers/pci/controller/dwc/pcie-designware.c > > > > > +++ b/drivers/pci/controller/dwc/pcie-designware.c > > > > > @@ -644,9 +644,20 @@ void dw_pcie_disable_atu(struct dw_pcie *pci, > > u32 dir, int index) > > > > > dw_pcie_writel_atu(pci, dir, index, PCIE_ATU_REGION_CTRL2, 0); > > > > > } > > > > > > > > > > -int dw_pcie_wait_for_link(struct dw_pcie *pci) > > > > > +void dw_pcie_print_link_status(struct dw_pcie *pci) > > > > > { > > > > > u32 offset, val; > > > > > + > > > > > + offset = dw_pcie_find_capability(pci, PCI_CAP_ID_EXP); > > > > > + val = dw_pcie_readw_dbi(pci, offset + PCI_EXP_LNKSTA); > > > > > + > > > > > + dev_info(pci->dev, "PCIe Gen.%u x%u link up\n", > > > > > + FIELD_GET(PCI_EXP_LNKSTA_CLS, val), > > > > > + FIELD_GET(PCI_EXP_LNKSTA_NLW, val)); > > > > > +} > > > > > + > > > > > +int dw_pcie_wait_for_link(struct dw_pcie *pci) > > > > > +{ > > > > > int retries; > > > > > > > > > > /* Check if the link is up or not */ > > > > > @@ -662,12 +673,7 @@ int dw_pcie_wait_for_link(struct dw_pcie *pci) > > > > > return -ETIMEDOUT; > > > > > } > > > > > > > > > > - offset = dw_pcie_find_capability(pci, PCI_CAP_ID_EXP); > > > > > - val = dw_pcie_readw_dbi(pci, offset + PCI_EXP_LNKSTA); > > > > > - > > > > > - dev_info(pci->dev, "PCIe Gen.%u x%u link up\n", > > > > > - FIELD_GET(PCI_EXP_LNKSTA_CLS, val), > > > > > - FIELD_GET(PCI_EXP_LNKSTA_NLW, val)); > > > > > + dw_pcie_print_link_status(pci); > > > > > > > > > > return 0; > > > > > } > > > > > diff --git a/drivers/pci/controller/dwc/pcie-designware.h > > b/drivers/pci/controller/dwc/pcie-designware.h > > > > > index 79713ce075cc..615660640801 100644 > > > > > --- a/drivers/pci/controller/dwc/pcie-designware.h > > > > > +++ b/drivers/pci/controller/dwc/pcie-designware.h > > > > > @@ -429,6 +429,7 @@ void dw_pcie_setup(struct dw_pcie *pci); > > > > > void dw_pcie_iatu_detect(struct dw_pcie *pci); > > > > > int dw_pcie_edma_detect(struct dw_pcie *pci); > > > > > void dw_pcie_edma_remove(struct dw_pcie *pci); > > > > > +void dw_pcie_print_link_status(struct dw_pcie *pci); > > > > > > > > > > static inline void dw_pcie_writel_dbi(struct dw_pcie *pci, u32 reg, > > u32 val) > > > > > { > > > > > -- > > > > > 2.40.0.577.gac1e443424-goog > > > > > > > > > > > > > Thanks for sending this patch Ajay! I tested this on my Pixel 6 with > > 6.3-rc1. > > > > I verified the PCIe RC probes without the 1s delay in > > dw_pcie_wait_for_link(). > > > > Feel free to include > > > > > > > > Tested-by: Will McVicker > > Hi Lorenzo, Could you confirm that you'll be taking this patch for the v6.5 main PCI branch please? Thanks, Will