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Message-ID: <20230802042738.GD2370@thinkpad>
Date: Wed, 2 Aug 2023 09:57:38 +0530
From: Manivannan Sadhasivam <mani@...nel.org>
To: Frank Li <Frank.Li@....com>
Cc: lpieralisi@...nel.org, bhelgaas@...gle.com,
devicetree@...r.kernel.org, gustavo.pimentel@...opsys.com,
helgaas@...nel.org, imx@...ts.linux.dev, kw@...ux.com,
leoyang.li@....com, linux-arm-kernel@...ts.infradead.org,
linux-imx@....com, linux-kernel@...r.kernel.org,
linux-pci@...r.kernel.org, lorenzo.pieralisi@....com,
manivannan.sadhasivam@...aro.org, minghuan.lian@....com,
mingkai.hu@....com, robh+dt@...nel.org, roy.zang@....com,
shawnguo@...nel.org, zhiqiang.hou@....com
Subject: Re: [PATCH v6 1/2] PCI: dwc: Implement general suspend/resume
functionality for L2/L3 transitions
On Mon, Jul 31, 2023 at 03:40:09PM -0400, Frank Li wrote:
> Introduce helper function dw_pcie_get_ltssm to retrieve SMLH_LTSS_STATE.
>
> Add callback .pme_turn_off and .exit_from_l2 for platform specific PME
> handle.
s/handle/handling
>
> Add common dw_pcie_suspend(resume)_noirq() API to avoid duplicated code
> in dwc pci host controller platform driver.
>
> Typical L2 entry workflow/dw_pcie_suspend_noirq()
>
> 1. Transmit PME turn off signal to PCI devices and wait for PME_To_Ack.
> 2. Await link entering L2_IDLE state.
>
> Typical L2 exit workflow/dw_pcie_resume_noirq()
>
> 1. Issue exit from L2 command.
> 2. Reinitialize PCI host.
> 3. Wait for link to become active.
>
> Signed-off-by: Frank Li <Frank.Li@....com>
> ---
> Change from v5 to v6:
> - refine commit message
> change according to Manivannan's comments.
> - remove reduncate step dw_pcie_set_dstate()
> - return 0 when .pme_turn_off is zero
> - call host_deinit() in suspend
> - check .host_deinit and .host_init point before call.
>
> Change from v4 to v5:
> - Closes: https://lore.kernel.org/oe-kbuild-all/202307211904.zExw4Q8H-lkp@intel.com/
> Change from v3 to v4:
> - change according to Manivannan's comments.
> I hope I have not missed anything. quite long discuss thread
> Change from v2 to v3:
> - Basic rewrite whole patch according rob herry suggestion.
> put common function into dwc, so more soc can share the same logic.
>
> .../pci/controller/dwc/pcie-designware-host.c | 78 +++++++++++++++++++
> drivers/pci/controller/dwc/pcie-designware.h | 28 +++++++
> 2 files changed, 106 insertions(+)
>
> diff --git a/drivers/pci/controller/dwc/pcie-designware-host.c b/drivers/pci/controller/dwc/pcie-designware-host.c
> index 9952057c8819c..1822c04d370b2 100644
> --- a/drivers/pci/controller/dwc/pcie-designware-host.c
> +++ b/drivers/pci/controller/dwc/pcie-designware-host.c
> @@ -8,6 +8,7 @@
> * Author: Jingoo Han <jg1.han@...sung.com>
> */
>
> +#include <linux/iopoll.h>
> #include <linux/irqchip/chained_irq.h>
> #include <linux/irqdomain.h>
> #include <linux/msi.h>
> @@ -807,3 +808,80 @@ int dw_pcie_setup_rc(struct dw_pcie_rp *pp)
> return 0;
> }
> EXPORT_SYMBOL_GPL(dw_pcie_setup_rc);
> +
> +int dw_pcie_suspend_noirq(struct dw_pcie *pci)
> +{
> + u8 offset = dw_pcie_find_capability(pci, PCI_CAP_ID_EXP);
> + u32 val;
> + int ret;
> +
> + /*
> + * If L1SS is supported, then do not put the link into L2 as some
> + * devices such as NVMe expect low resume latency.
> + */
> + if (dw_pcie_readw_dbi(pci, offset + PCI_EXP_LNKCTL) & PCI_EXP_LNKCTL_ASPM_L1)
> + return 0;
> +
> + if (dw_pcie_get_ltssm(pci) <= DW_PCIE_LTSSM_DETECT_ACT)
> + return 0;
> +
> + if (!pci->pp.ops->pme_turn_off)
> + return 0;
> +
> + pci->pp.ops->pme_turn_off(&pci->pp);
> +
> + /*
> + * PCI Express Base Specification Rev 4.0 5.3.3.2.1 PME Synchronization
Rev 4.0 Section 5.3.3.2.1
> + * Recommands 1ms to 10ms timeout to check L2 ready
Recommends
Also add a full stop at the end of line.
> + */
> + ret = read_poll_timeout(dw_pcie_get_ltssm, val, val == DW_PCIE_LTSSM_L2_IDLE,
> + 100, 10000, false, pci);
sleep_us value should be 1000 for 1ms.
> + if (ret) {
> + dev_err(pci->dev, "Timeout waiting for L2 entry! LTSSM: 0x%x\n", val);
> + return ret;
> + }
> +
> + if (pci->pp.ops->host_deinit)
> + pci->pp.ops->host_deinit(&pci->pp);
> +
> + pci->suspended = true;
> +
> + return ret;
> +}
> +EXPORT_SYMBOL_GPL(dw_pcie_suspend_noirq);
> +
> +int dw_pcie_resume_noirq(struct dw_pcie *pci)
> +{
> + int ret;
> +
> + if (!pci->suspended)
> + return 0;
> +
> + pci->suspended = false;
> +
> + if (!pci->pp.ops->exit_from_l2)
> + return 0;
> +
> + pci->pp.ops->exit_from_l2(&pci->pp);
> +
> + if (pci->pp.ops->host_init) {
> + ret = pci->pp.ops->host_init(&pci->pp);
> + if (ret) {
> + dev_err(pci->dev, "Host init failed! ret = 0x%x\n", ret);
Why do you want to print "ret" in hex?
How about,
dev_err(pci->dev, "Host init failed: %d\n", ret);
Rest looks good!
- Mani
> + return ret;
> + }
> + }
> +
> + dw_pcie_setup_rc(&pci->pp);
> +
> + ret = dw_pcie_start_link(pci);
> + if (ret)
> + return ret;
> +
> + ret = dw_pcie_wait_for_link(pci);
> + if (ret)
> + return ret;
> +
> + return ret;
> +}
> +EXPORT_SYMBOL_GPL(dw_pcie_resume_noirq);
> diff --git a/drivers/pci/controller/dwc/pcie-designware.h b/drivers/pci/controller/dwc/pcie-designware.h
> index 79713ce075cc1..cbba3ed19b3c0 100644
> --- a/drivers/pci/controller/dwc/pcie-designware.h
> +++ b/drivers/pci/controller/dwc/pcie-designware.h
> @@ -288,10 +288,21 @@ enum dw_pcie_core_rst {
> DW_PCIE_NUM_CORE_RSTS
> };
>
> +enum dw_pcie_ltssm {
> + DW_PCIE_LTSSM_UNKNOWN = 0xFFFFFFFF,
> + /* Need to align with PCIE_PORT_DEBUG0 bits 0:5 */
> + DW_PCIE_LTSSM_DETECT_QUIET = 0x0,
> + DW_PCIE_LTSSM_DETECT_ACT = 0x1,
> + DW_PCIE_LTSSM_L0 = 0x11,
> + DW_PCIE_LTSSM_L2_IDLE = 0x15,
> +};
> +
> struct dw_pcie_host_ops {
> int (*host_init)(struct dw_pcie_rp *pp);
> void (*host_deinit)(struct dw_pcie_rp *pp);
> int (*msi_host_init)(struct dw_pcie_rp *pp);
> + void (*pme_turn_off)(struct dw_pcie_rp *pp);
> + void (*exit_from_l2)(struct dw_pcie_rp *pp);
> };
>
> struct dw_pcie_rp {
> @@ -364,6 +375,7 @@ struct dw_pcie_ops {
> void (*write_dbi2)(struct dw_pcie *pcie, void __iomem *base, u32 reg,
> size_t size, u32 val);
> int (*link_up)(struct dw_pcie *pcie);
> + enum dw_pcie_ltssm (*get_ltssm)(struct dw_pcie *pcie);
> int (*start_link)(struct dw_pcie *pcie);
> void (*stop_link)(struct dw_pcie *pcie);
> };
> @@ -393,6 +405,7 @@ struct dw_pcie {
> struct reset_control_bulk_data app_rsts[DW_PCIE_NUM_APP_RSTS];
> struct reset_control_bulk_data core_rsts[DW_PCIE_NUM_CORE_RSTS];
> struct gpio_desc *pe_rst;
> + bool suspended;
> };
>
> #define to_dw_pcie_from_pp(port) container_of((port), struct dw_pcie, pp)
> @@ -430,6 +443,9 @@ 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);
>
> +int dw_pcie_suspend_noirq(struct dw_pcie *pci);
> +int dw_pcie_resume_noirq(struct dw_pcie *pci);
> +
> static inline void dw_pcie_writel_dbi(struct dw_pcie *pci, u32 reg, u32 val)
> {
> dw_pcie_write_dbi(pci, reg, 0x4, val);
> @@ -501,6 +517,18 @@ static inline void dw_pcie_stop_link(struct dw_pcie *pci)
> pci->ops->stop_link(pci);
> }
>
> +static inline enum dw_pcie_ltssm dw_pcie_get_ltssm(struct dw_pcie *pci)
> +{
> + u32 val;
> +
> + if (pci->ops && pci->ops->get_ltssm)
> + return pci->ops->get_ltssm(pci);
> +
> + val = dw_pcie_readl_dbi(pci, PCIE_PORT_DEBUG0);
> +
> + return (enum dw_pcie_ltssm)FIELD_GET(PORT_LOGIC_LTSSM_STATE_MASK, val);
> +}
> +
> #ifdef CONFIG_PCIE_DW_HOST
> irqreturn_t dw_handle_msi_irq(struct dw_pcie_rp *pp);
> int dw_pcie_setup_rc(struct dw_pcie_rp *pp);
> --
> 2.34.1
>
--
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