linux-kernel - Re: [PATCH v3 4/4] PCI: layerscape: Add suspend/resume for ls1043a

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Message-ID: <20231102173900.GF20943@thinkpad>
Date:   Thu, 2 Nov 2023 23:09:00 +0530
From:   Manivannan Sadhasivam <manivannan.sadhasivam@...aro.org>
To:     Frank Li <Frank.Li@....com>
Cc:     bhelgaas@...gle.com, imx@...ts.linux.dev, kw@...ux.com,
        linux-arm-kernel@...ts.infradead.org, linux-kernel@...r.kernel.org,
        linux-pci@...r.kernel.org, linuxppc-dev@...ts.ozlabs.org,
        lpieralisi@...nel.org, minghuan.Lian@....com, mingkai.hu@....com,
        robh@...nel.org, roy.zang@....com
Subject: Re: [PATCH v3 4/4] PCI: layerscape: Add suspend/resume for ls1043a

On Tue, Oct 17, 2023 at 03:31:45PM -0400, Frank Li wrote:
> ls1043a add suspend/resume support.
> Implement ls1043a_pcie_send_turnoff_msg() to send PME_Turn_Off message.
> Implement ls1043a_pcie_exit_from_l2() to exit from L2 state.
> 

Please use the suggestion I gave in patch 2/4.

> Signed-off-by: Frank Li <Frank.Li@....com>
> ---
> 
> Notes:
>     Change from v2 to v3
>     - Remove ls_pcie_lut_readl(writel) function
>     
>     Change from v1 to v2
>     - Update 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 4b663b20d8612..9656224960b0c 100644
> --- a/drivers/pci/controller/dwc/pci-layerscape.c
> +++ b/drivers/pci/controller/dwc/pci-layerscape.c
> @@ -41,6 +41,15 @@
>  #define SCFG_PEXSFTRSTCR	0x190
>  #define PEXSR(idx)		BIT(idx)
>  
> +/* LS1043A PEX PME control register */
> +#define SCFG_PEXPMECR		0x144
> +#define PEXPME(idx)		BIT(31 - (idx) * 4)
> +
> +/* LS1043A PEX LUT debug register */
> +#define LS_PCIE_LDBG	0x7fc
> +#define LDBG_SR		BIT(30)
> +#define LDBG_WE		BIT(31)
> +
>  #define PCIE_IATU_NUM		6
>  
>  #define LS_PCIE_DRV_SCFG	BIT(0)
> @@ -227,6 +236,68 @@ static int ls1021a_pcie_exit_from_l2(struct dw_pcie_rp *pp)
>  	return 0;
>  }
>  
> +static void ls1043a_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;
> +
> +	if (!pcie->scfg) {
> +		dev_dbg(pcie->pci->dev, "SYSCFG is NULL\n");
> +		return;
> +	}

Why scfg is optional for this SoC and not for the other one added in patch 2/4?

> +
> +	/* Send Turn_off message */
> +	regmap_read(pcie->scfg, SCFG_PEXPMECR, &val);
> +	val |= PEXPME(pcie->index);
> +	regmap_write(pcie->scfg, SCFG_PEXPMECR, val);
> +

In my previous review, I asked you to use a common function and just pass the
offsets, as the sequence is same for both the SoCs. But you ignored it :/

> +	/*
> +	 * 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_PEXPMECR, &val);
> +	val &= ~PEXPME(pcie->index);
> +	regmap_write(pcie->scfg, SCFG_PEXPMECR, val);
> +}
> +
> +static int ls1043a_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 let PEX module exit L2 is do a software reset.

Same comment applies as patch 2/4.

- Mani

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