From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 54671C4332F for ; Thu, 2 Nov 2023 17:28:26 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S229488AbjKBR21 (ORCPT ); Thu, 2 Nov 2023 13:28:27 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:56472 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229479AbjKBR20 (ORCPT ); Thu, 2 Nov 2023 13:28:26 -0400 Received: from mail-yb1-xb29.google.com (mail-yb1-xb29.google.com [IPv6:2607:f8b0:4864:20::b29]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 0E64C182 for ; Thu, 2 Nov 2023 10:28:20 -0700 (PDT) Received: by mail-yb1-xb29.google.com with SMTP id 3f1490d57ef6-d9beb863816so1218757276.1 for ; Thu, 02 Nov 2023 10:28:20 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linaro.org; s=google; t=1698946099; x=1699550899; darn=vger.kernel.org; h=in-reply-to:content-transfer-encoding:content-disposition :mime-version:references:message-id:subject:cc:to:from:date:from:to :cc:subject:date:message-id:reply-to; bh=tNkygFU/hw8zUOPQ7Nync2PfCNdVcXfa85CS1trX39M=; b=kbG99X2cV0Quktb5nOmK2w+x2cKpHFFaOxqaTT9ajc09PI6DvpcspSybdMtITnf+Fm j+eZ6H3LoH0/WFkO9MjWkqt1Pj74JKZSHfYp1ztPfIfpKILSLDvuaADq1cYcItGGNpUx cRAtnHJL9pK/vdxmqqd+edHjwQ6AuRR17HaA4mfPGGJzuV+Ndd1shl0WNLUD7O8Oqjgj uFrvy2CeRKj8w97xhMhuvCKyzzdKz1W/xjp3p2rhSidAbyTk9L8Yk2wv50gWirxJJAfd UaaKhnG7xu1o05t0T9DNeeq706a/2x+Hy+Nc+bMY0sHLURGym/dHzHEZsT8UPWWQVjg0 4Pwg== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20230601; t=1698946099; x=1699550899; h=in-reply-to:content-transfer-encoding:content-disposition :mime-version:references:message-id:subject:cc:to:from:date :x-gm-message-state:from:to:cc:subject:date:message-id:reply-to; bh=tNkygFU/hw8zUOPQ7Nync2PfCNdVcXfa85CS1trX39M=; b=My3LVwuH0w7Nxgy9ZxCS7ynUi4HXQaGNQw5OOSMnhjsJG/tV68AUFrx+NgNdijMHVw Maf5UepVnuMjIAKV86/o51zA5yCwlk1PQAnKiyjvAPkXZJYXBqMa4KPRgOSiyP8+fSEN 8kkbhrJV+SUUEAp0CU+KAGdXSoL7diD/gGHbcwGZEBHiDqGWo21s+7CxGoXCgLPihpTV fbts62C0Q/KX92igqKjjrKstYZjy7mXldURHVGFZ8yi4NRgIhDpcH6/dsi0Mi1XCBlwX rSZn7AEPNIaeBT/IPiGprD0Li3uW/iWaBZ4Q0ibDrAetckL4fCOEKoUg87fADXpAPIvm 31hA== X-Gm-Message-State: AOJu0YxBar7By+tiLL2b5V5UKxdBHlIDMLP1XTcW902CRvKRMEUt34uQ pXMptf6+bQoAx9s8N0rMlIgf X-Google-Smtp-Source: AGHT+IH7fibGIbeWFf4lq3wUpjaMim+uaJtvzKp2sOzZPKo9u8eoqjbUNEnwl5inK43EbeNu+CLkqA== X-Received: by 2002:a5b:706:0:b0:da0:c49a:5103 with SMTP id g6-20020a5b0706000000b00da0c49a5103mr17816802ybq.47.1698946099126; Thu, 02 Nov 2023 10:28:19 -0700 (PDT) Received: from thinkpad ([117.217.189.228]) by smtp.gmail.com with ESMTPSA id p8-20020ad452e8000000b0066d1e71e515sm121935qvu.113.2023.11.02.10.28.14 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Thu, 02 Nov 2023 10:28:18 -0700 (PDT) Date: Thu, 2 Nov 2023 22:58:09 +0530 From: Manivannan Sadhasivam To: Frank Li Cc: bhelgaas@google.com, imx@lists.linux.dev, kw@linux.com, linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org, linux-pci@vger.kernel.org, linuxppc-dev@lists.ozlabs.org, lpieralisi@kernel.org, minghuan.Lian@nxp.com, mingkai.hu@nxp.com, robh@kernel.org, roy.zang@nxp.com Subject: Re: [PATCH v3 2/4] PCI: layerscape: Add suspend/resume for ls1021a Message-ID: <20231102172809.GD20943@thinkpad> References: <20231017193145.3198380-1-Frank.Li@nxp.com> <20231017193145.3198380-3-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: <20231017193145.3198380-3-Frank.Li@nxp.com> Precedence: bulk List-ID: X-Mailing-List: linux-pci@vger.kernel.org On Tue, Oct 17, 2023 at 03:31:43PM -0400, Frank Li wrote: > ls1021a add suspend/resume support. > > Implement callback ls1021a_pcie_send_turnoff_msg(), which write scfg's > SCFG_PEXPMWRCR to issue PME_Turn_off message. > > Implement ls1021a_pcie_exit_from_l2() to let controller exit L2 state. > I'd like to reword it to better reflect what the patch does: "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 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." Although I do have questions on the resume behavior below. > Signed-off-by: Frank Li > --- > > Notes: > 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 | 86 ++++++++++++++++++++- > 1 file changed, 85 insertions(+), 1 deletion(-) > > diff --git a/drivers/pci/controller/dwc/pci-layerscape.c b/drivers/pci/controller/dwc/pci-layerscape.c > index aea89926bcc4f..6f47cfe146c44 100644 > --- a/drivers/pci/controller/dwc/pci-layerscape.c > +++ b/drivers/pci/controller/dwc/pci-layerscape.c > @@ -35,11 +35,21 @@ > #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 > > +#define LS_PCIE_DRV_SCFG BIT(0) > + > struct ls_pcie_drvdata { > const u32 pf_off; > + const struct dw_pcie_host_ops *ops; > int (*exit_from_l2)(struct dw_pcie_rp *pp); > + int flags; Why not "bool scfg_support"? > bool pm_support; > }; > > @@ -47,6 +57,8 @@ 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 +183,65 @@ static int ls_pcie_host_init(struct dw_pcie_rp *pp) > return 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); > + u32 val; > + > + /* Send PME_Turn_Off message */ > + regmap_read(pcie->scfg, SCFG_PEXPMWRCR(pcie->index), &val); > + val |= PMXMTTURNOFF; > + regmap_write(pcie->scfg, SCFG_PEXPMWRCR(pcie->index), val); > + > + /* > + * 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_read(pcie->scfg, SCFG_PEXPMWRCR(pcie->index), &val); > + val &= ~PMXMTTURNOFF; > + regmap_write(pcie->scfg, SCFG_PEXPMWRCR(pcie->index), val); > +} > + > +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); > + u32 val; > + > + /* Only way exit from l2 is that do software reset */ So, what does exactly "software reset" mean? Are you resetting the endpoint or some specific registers/blocks in the controller? Also, what if the link goes to L3 in the case of no VAUX? > + regmap_read(pcie->scfg, SCFG_PEXSFTRSTCR, &val); > + val |= PEXSR(pcie->index); > + regmap_write(pcie->scfg, SCFG_PEXSFTRSTCR, val); > + > + regmap_read(pcie->scfg, SCFG_PEXSFTRSTCR, &val); > + val &= ~PEXSR(pcie->index); > + regmap_write(pcie->scfg, SCFG_PEXSFTRSTCR, val); > + > + return 0; > +} > + > 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, > + .ops = &ls1021a_pcie_host_ops, > + .exit_from_l2 = ls1021a_pcie_exit_from_l2, > + .flags = LS_PCIE_DRV_SCFG, > }; > > static const struct ls_pcie_drvdata layerscape_drvdata = { > @@ -205,6 +269,8 @@ 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 +286,7 @@ 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; > > dbi_base = platform_get_resource_byname(pdev, IORESOURCE_MEM, "regs"); > pci->dbi_base = devm_pci_remap_cfg_resource(dev, dbi_base); > @@ -230,6 +297,23 @@ static int ls_pcie_probe(struct platform_device *pdev) > > pcie->pf_base = pci->dbi_base + pcie->drvdata->pf_off; > > + if (pcie->drvdata->flags & LS_PCIE_DRV_SCFG) { > + Remove extra newline. - Mani -- மணிவண்ணன் சதாசிவம்