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Sat, 20 Jan 2024 06:34:42 -0800 (PST) Received: from thinkpad ([117.202.189.10]) by smtp.gmail.com with ESMTPSA id z2-20020aa785c2000000b006d99d986624sm6802791pfn.151.2024.01.20.06.34.37 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Sat, 20 Jan 2024 06:34:42 -0800 (PST) Date: Sat, 20 Jan 2024 20:04:34 +0530 From: Manivannan Sadhasivam To: Ajay Agarwal Cc: Jingoo Han , Johan Hovold , Jon Hunter , Lorenzo Pieralisi , Krzysztof =?utf-8?Q?Wilczy=C5=84ski?= , Rob Herring , Bjorn Helgaas , Manu Gautam , Doug Zobel , William McVicker , Serge Semin , Robin Murphy , linux-pci@vger.kernel.org Subject: Re: [PATCH v5] PCI: dwc: Wait for link up only if link is started Message-ID: <20240120143434.GA5405@thinkpad> References: <20240112093006.2832105-1-ajayagarwal@google.com> <20240119075219.GC2866@thinkpad> Precedence: bulk X-Mailing-List: linux-pci@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: On Fri, Jan 19, 2024 at 11:29:22PM +0530, Ajay Agarwal wrote: > On Fri, Jan 19, 2024 at 01:22:19PM +0530, Manivannan Sadhasivam wrote: > > On Fri, Jan 12, 2024 at 03:00:06PM +0530, 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. > > > > > > > Which platform you are working on? Is that upstreamed? You should mention the > > specific platform where you are observing the issue. > > > This is for the Pixel phone platform. The platform driver for the same > is not upstreamed yet. It is in the process. > Then you should submit this patch at the time of the driver submission. Right now, you are trying to fix a problem which is not present in upstream. One can argue that it is a problem for designware-plat driver, but honestly I do not know how it works. - Mani > > Right now, intel-gw and designware-plat are the only drivers not defining that > > callback. First one definitely needs a fixup and I do not know how the latter > > works. > > > > - Mani > > > > > Wait for the link up in only if the start_link() is defined. > > > > > > Signed-off-by: Ajay Agarwal > > > --- > > > v4 was applied, but then reverted. The reason being v4 added a > > > regression on some products which expect the link to not come up as a > > > part of the probe. Since v4 returned error from dw_pcie_wait_for_link > > > check, the probe function of these products started to fail. > > > > > > Changelog since v4: > > > - Do not return error from dw_pcie_wait_for_link check > > > > > > .../pci/controller/dwc/pcie-designware-host.c | 12 +++++++---- > > > drivers/pci/controller/dwc/pcie-designware.c | 20 ++++++++++++------- > > > drivers/pci/controller/dwc/pcie-designware.h | 1 + > > > 3 files changed, 22 insertions(+), 11 deletions(-) > > > > > > diff --git a/drivers/pci/controller/dwc/pcie-designware-host.c b/drivers/pci/controller/dwc/pcie-designware-host.c > > > index 7991f0e179b2..e53132663d1d 100644 > > > --- a/drivers/pci/controller/dwc/pcie-designware-host.c > > > +++ b/drivers/pci/controller/dwc/pcie-designware-host.c > > > @@ -487,14 +487,18 @@ 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) { > > > + /* Ignore errors, the link may come up later */ > > > + dw_pcie_wait_for_link(pci); > > > + } > > > + } > > > > > > bridge->sysdata = pp; > > > > > > diff --git a/drivers/pci/controller/dwc/pcie-designware.c b/drivers/pci/controller/dwc/pcie-designware.c > > > index 250cf7f40b85..c067d2e960cf 100644 > > > --- a/drivers/pci/controller/dwc/pcie-designware.c > > > +++ b/drivers/pci/controller/dwc/pcie-designware.c > > > @@ -645,9 +645,20 @@ 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 */ > > > @@ -663,12 +674,7 @@ 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 55ff76e3d384..164214a7219a 100644 > > > --- a/drivers/pci/controller/dwc/pcie-designware.h > > > +++ b/drivers/pci/controller/dwc/pcie-designware.h > > > @@ -447,6 +447,7 @@ 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); > > > > > > int dw_pcie_suspend_noirq(struct dw_pcie *pci); > > > int dw_pcie_resume_noirq(struct dw_pcie *pci); > > > -- > > > 2.43.0.381.gb435a96ce8-goog > > > > > > > -- > > மணிவண்ணன் சதாசிவம் -- மணிவண்ணன் சதாசிவம்