linux-kernel - Re: [PATCH v3 06/11] PCI: brcmstb: Avoid turn off of bridge reset

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Message-ID: <CANCKTBt-QAOytUSp6=HcS_SiPD7wSOFdFv2U=4c146uzmdinAQ@mail.gmail.com>
Date: Wed, 16 Oct 2024 13:17:06 -0400
From: Jim Quinlan <jim2101024@...il.com>
To: Stanimir Varbanov <svarbanov@...e.de>
Cc: linux-kernel@...r.kernel.org, devicetree@...r.kernel.org, 
	linux-arm-kernel@...ts.infradead.org, linux-rpi-kernel@...ts.infradead.org, 
	linux-pci@...r.kernel.org, 
	Broadcom internal kernel review list <bcm-kernel-feedback-list@...adcom.com>, 
	Thomas Gleixner <tglx@...utronix.de>, Rob Herring <robh@...nel.org>, 
	Krzysztof Kozlowski <krzk+dt@...nel.org>, Conor Dooley <conor+dt@...nel.org>, 
	Florian Fainelli <florian.fainelli@...adcom.com>, Nicolas Saenz Julienne <nsaenz@...nel.org>, 
	Bjorn Helgaas <bhelgaas@...gle.com>, Lorenzo Pieralisi <lpieralisi@...nel.org>, kw@...ux.com, 
	Philipp Zabel <p.zabel@...gutronix.de>, Andrea della Porta <andrea.porta@...e.com>, 
	Phil Elwell <phil@...pberrypi.com>, Jonathan Bell <jonathan@...pberrypi.com>
Subject: Re: [PATCH v3 06/11] PCI: brcmstb: Avoid turn off of bridge reset

On Mon, Oct 14, 2024 at 9:07 AM Stanimir Varbanov <svarbanov@...e.de> wrote:
>
> On PCIe turn off avoid shutdown of bridge reset,
> by introducing a quirk flag.
>
> Signed-off-by: Stanimir Varbanov <svarbanov@...e.de>
> ---
> v2 -> v3:
>  - Added more descriptive comment on CFG_QUIRK_AVOID_BRIDGE_SHUTDOWN quirk.
>
>  drivers/pci/controller/pcie-brcmstb.c | 17 +++++++++++++++--
>  1 file changed, 15 insertions(+), 2 deletions(-)
>
> diff --git a/drivers/pci/controller/pcie-brcmstb.c b/drivers/pci/controller/pcie-brcmstb.c
> index b76c16287f37..757a1646d53c 100644
> --- a/drivers/pci/controller/pcie-brcmstb.c
> +++ b/drivers/pci/controller/pcie-brcmstb.c
> @@ -234,10 +234,20 @@ struct inbound_win {
>         u64 cpu_addr;
>  };
>
> +/*
> + * The RESCAL block is tied to PCIe controller #1, regardless of the number of
> + * controllers, and turning off PCIe controller #1 prevents access to the RESCAL
> + * register blocks, therefore not other controller can access this register

s/no/not/

I assume that the quirks is specific to 2712 as the 7712 does not need
this since it only has PCIe1
(I'll probably seethis as I read more of your commits).

-- Jim

> + * space, and depending upon the bus fabric we may get a timeout (UBUS/GISB),
> + * or a hang (AXI).
> + */
> +#define CFG_QUIRK_AVOID_BRIDGE_SHUTDOWN                BIT(0)
> +
>  struct pcie_cfg_data {
>         const int *offsets;
>         const enum pcie_soc_base soc_base;
>         const bool has_phy;
> +       const u32 quirks;
>         u8 num_inbound_wins;
>         int (*perst_set)(struct brcm_pcie *pcie, u32 val);
>         int (*bridge_sw_init_set)(struct brcm_pcie *pcie, u32 val);
> @@ -290,6 +300,7 @@ struct brcm_pcie {
>         struct subdev_regulators *sr;
>         bool                    ep_wakeup_capable;
>         bool                    has_phy;
> +       u32                     quirks;
>         u8                      num_inbound_wins;
>  };
>
> @@ -1539,8 +1550,9 @@ static int brcm_pcie_turn_off(struct brcm_pcie *pcie)
>         u32p_replace_bits(&tmp, 1, PCIE_MISC_HARD_PCIE_HARD_DEBUG_SERDES_IDDQ_MASK);
>         writel(tmp, base + HARD_DEBUG(pcie));
>
> -       /* Shutdown PCIe bridge */
> -       ret = pcie->bridge_sw_init_set(pcie, 1);
> +       if (!(pcie->quirks & CFG_QUIRK_AVOID_BRIDGE_SHUTDOWN))
> +               /* Shutdown PCIe bridge */
> +               ret = pcie->bridge_sw_init_set(pcie, 1);
>
>         return ret;
>  }
> @@ -1854,6 +1866,7 @@ static int brcm_pcie_probe(struct platform_device *pdev)
>         pcie->perst_set = data->perst_set;
>         pcie->bridge_sw_init_set = data->bridge_sw_init_set;
>         pcie->has_phy = data->has_phy;
> +       pcie->quirks = data->quirks;
>         pcie->num_inbound_wins = data->num_inbound_wins;
>
>         pcie->base = devm_platform_ioremap_resource(pdev, 0);
> --
> 2.43.0
>