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Thu, 30 Nov 2023 08:43:33 -0800 (PST) Received: from thinkpad ([117.213.102.92]) by smtp.gmail.com with ESMTPSA id bm27-20020a05620a199b00b0077da0832d6csm639505qkb.22.2023.11.30.08.43.28 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Thu, 30 Nov 2023 08:43:32 -0800 (PST) Date: Thu, 30 Nov 2023 22:13:23 +0530 From: Manivannan Sadhasivam To: Frank Li Subject: Re: [PATCH v4 2/4] PCI: layerscape: Add suspend/resume for ls1021a Message-ID: <20231130164323.GT3043@thinkpad> References: <20231129214412.327633-1-Frank.Li@nxp.com> <20231129214412.327633-3-Frank.Li@nxp.com> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: <20231129214412.327633-3-Frank.Li@nxp.com> X-BeenThere: linuxppc-dev@lists.ozlabs.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: Linux on PowerPC Developers Mail List List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: imx@lists.linux.dev, kw@linux.com, linux-pci@vger.kernel.org, lpieralisi@kernel.org, linux-kernel@vger.kernel.org, minghuan.Lian@nxp.com, mingkai.hu@nxp.com, roy.zang@nxp.com, bhelgaas@google.com, linuxppc-dev@lists.ozlabs.org, robh@kernel.org, linux-arm-kernel@lists.infradead.org Errors-To: linuxppc-dev-bounces+linuxppc-dev=archiver.kernel.org@lists.ozlabs.org Sender: "Linuxppc-dev" On Wed, Nov 29, 2023 at 04:44:10PM -0500, Frank Li wrote: > ls1021a add suspend/resume support. > "Add suspend/resume support for Layerscape LS1021a" > In the suspend path, PME_Turn_Off message is sent to the endpoint to > transition the link to L2/L3_Ready state. In this SoC, there is no way to > check if the controller has received the PME_To_Ack from the endpoint or > not. So to be on the safer side, the driver just waits for > PCIE_PME_TO_L2_TIMEOUT_US before asserting the SoC specific PMXMTTURNOFF > bit to complete the PME_Turn_Off handshake. This link would then enter "Then the link would enter L2/L3 state depending on the VAUX supply." > L2/L3 state depending on the VAUX supply. > > In the resume path, the link is brought back from L2 to L0 by doing a > software reset. > > Signed-off-by: Frank Li Couple of comments below. But the patch is looking good now. Thanks for the update. > --- > > Notes: > Change from v3 to v4 > - update commit message. > - it is reset a glue logic part for PCI controller. > - use regmap_write_bits() to reduce code change. > > Change from v2 to v3 > - update according to mani's feedback > change from v1 to v2 > - change subject 'a' to 'A' > > drivers/pci/controller/dwc/pci-layerscape.c | 83 ++++++++++++++++++++- > 1 file changed, 82 insertions(+), 1 deletion(-) > > diff --git a/drivers/pci/controller/dwc/pci-layerscape.c b/drivers/pci/controller/dwc/pci-layerscape.c > index aea89926bcc4f..42bca2c3b5c3e 100644 > --- a/drivers/pci/controller/dwc/pci-layerscape.c > +++ b/drivers/pci/controller/dwc/pci-layerscape.c > @@ -35,11 +35,19 @@ > #define PF_MCR_PTOMR BIT(0) > #define PF_MCR_EXL2S BIT(1) > > +/* LS1021A PEXn PM Write Control Register */ > +#define SCFG_PEXPMWRCR(idx) (0x5c + (idx) * 0x64) > +#define PMXMTTURNOFF BIT(31) > +#define SCFG_PEXSFTRSTCR 0x190 > +#define PEXSR(idx) BIT(idx) > + > #define PCIE_IATU_NUM 6 > > struct ls_pcie_drvdata { > const u32 pf_off; > + const struct dw_pcie_host_ops *ops; > int (*exit_from_l2)(struct dw_pcie_rp *pp); > + bool scfg_support; > bool pm_support; > }; > > @@ -47,6 +55,8 @@ struct ls_pcie { > struct dw_pcie *pci; > const struct ls_pcie_drvdata *drvdata; > void __iomem *pf_base; > + struct regmap *scfg; > + int index; > bool big_endian; > }; > > @@ -171,13 +181,65 @@ static int ls_pcie_host_init(struct dw_pcie_rp *pp) > return 0; > } > > +static void scfg_pcie_send_turnoff_msg(struct regmap *scfg, u32 reg, u32 mask) > +{ > + /* Send PME_Turn_Off message */ > + regmap_write_bits(scfg, reg, mask, mask); > + > + /* > + * There is no specific register to check for PME_To_Ack from endpoint. > + * So on the safe side, wait for PCIE_PME_TO_L2_TIMEOUT_US. > + */ > + mdelay(PCIE_PME_TO_L2_TIMEOUT_US/1000); > + > + /* > + * Layerscape hardware reference manual recommends clearing the PMXMTTURNOFF bit > + * to complete the PME_Turn_Off handshake. > + */ > + regmap_write_bits(scfg, reg, mask, 0); > +} > + > +static void ls1021a_pcie_send_turnoff_msg(struct dw_pcie_rp *pp) > +{ > + struct dw_pcie *pci = to_dw_pcie_from_pp(pp); > + struct ls_pcie *pcie = to_ls_pcie(pci); > + > + scfg_pcie_send_turnoff_msg(pcie->scfg, SCFG_PEXPMWRCR(pcie->index), PMXMTTURNOFF); > +} > + > +static int scfg_pcie_exit_from_l2(struct regmap *scfg, u32 reg, u32 mask) > +{ > + /* Only way exit from l2 is that do software reset */ "Only way exit from L2 is by doing a software reset of the controller" I really hope that the reset is not a global controller reset i.e., not resetting all CSRs. > + regmap_write_bits(scfg, reg, mask, mask); > + No need of a newline. > + regmap_write_bits(scfg, reg, mask, 0); > + > + return 0; > +} > + > +static int ls1021a_pcie_exit_from_l2(struct dw_pcie_rp *pp) > +{ > + struct dw_pcie *pci = to_dw_pcie_from_pp(pp); > + struct ls_pcie *pcie = to_ls_pcie(pci); > + > + return scfg_pcie_exit_from_l2(pcie->scfg, SCFG_PEXSFTRSTCR, PEXSR(pcie->index)); > +} > + > static const struct dw_pcie_host_ops ls_pcie_host_ops = { > .host_init = ls_pcie_host_init, > .pme_turn_off = ls_pcie_send_turnoff_msg, > }; > > +static const struct dw_pcie_host_ops ls1021a_pcie_host_ops = { > + .host_init = ls_pcie_host_init, > + .pme_turn_off = ls1021a_pcie_send_turnoff_msg, > +}; > + > static const struct ls_pcie_drvdata ls1021a_drvdata = { > - .pm_support = false, > + .pm_support = true, > + .scfg_support = true, > + .ops = &ls1021a_pcie_host_ops, > + .exit_from_l2 = ls1021a_pcie_exit_from_l2, > }; > > static const struct ls_pcie_drvdata layerscape_drvdata = { > @@ -205,6 +267,8 @@ static int ls_pcie_probe(struct platform_device *pdev) > struct dw_pcie *pci; > struct ls_pcie *pcie; > struct resource *dbi_base; > + u32 index[2]; > + int ret; > > pcie = devm_kzalloc(dev, sizeof(*pcie), GFP_KERNEL); > if (!pcie) > @@ -220,6 +284,7 @@ static int ls_pcie_probe(struct platform_device *pdev) > pci->pp.ops = &ls_pcie_host_ops; > > pcie->pci = pci; > + pci->pp.ops = pcie->drvdata->ops ? pcie->drvdata->ops : &ls_pcie_host_ops; pp.ops is already assigned to &ls_pcie_host_ops above. But I think for consistency, you should pass ls_pcie_host_ops to the "ops" member of layerscape_drvdata and just use: pci->pp.ops = pcie->drvdata->ops; It looks a lot cleaner. > > dbi_base = platform_get_resource_byname(pdev, IORESOURCE_MEM, "regs"); > pci->dbi_base = devm_pci_remap_cfg_resource(dev, dbi_base); > @@ -230,6 +295,22 @@ static int ls_pcie_probe(struct platform_device *pdev) > > pcie->pf_base = pci->dbi_base + pcie->drvdata->pf_off; > > + if (pcie->drvdata->scfg_support) { > + pcie->scfg = syscon_regmap_lookup_by_phandle(dev->of_node, "fsl,pcie-scfg"); > + if (IS_ERR(pcie->scfg)) { > + dev_err(dev, "No syscfg phandle specified\n"); > + return PTR_ERR(pcie->scfg); > + } > + > + ret = of_property_read_u32_array(dev->of_node, "fsl,pcie-scfg", index, 2); > + if (ret) { > + pcie->scfg = NULL; No need to set it to NULL in the case of probe failure. - Mani -- மணிவண்ணன் சதாசிவம்