[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]
Message-ID: <20240917073824.GJ167971@kernel.org>
Date: Tue, 17 Sep 2024 08:38:24 +0100
From: Simon Horman <horms@...nel.org>
To: Wei Huang <wei.huang2@....com>
Cc: linux-pci@...r.kernel.org, linux-kernel@...r.kernel.org,
linux-doc@...r.kernel.org, netdev@...r.kernel.org,
Jonathan.Cameron@...wei.com, helgaas@...nel.org, corbet@....net,
davem@...emloft.net, edumazet@...gle.com, kuba@...nel.org,
pabeni@...hat.com, alex.williamson@...hat.com, gospo@...adcom.com,
michael.chan@...adcom.com, ajit.khaparde@...adcom.com,
somnath.kotur@...adcom.com, andrew.gospodarek@...adcom.com,
manoj.panicker2@....com, Eric.VanTassell@....com,
vadim.fedorenko@...ux.dev, bagasdotme@...il.com,
bhelgaas@...gle.com, lukas@...ner.de, paul.e.luse@...el.com,
jing2.liu@...el.com
Subject: Re: [PATCH V5 1/5] PCI: Add TLP Processing Hints (TPH) support
On Mon, Sep 16, 2024 at 03:50:59PM -0500, Wei Huang wrote:
> Add support for PCIe TLP Processing Hints (TPH) support (see PCIe r6.2,
> sec 6.17).
>
> Add missing TPH register definitions in pci_regs.h, including the TPH
> Requester capability register, TPH Requester control register, TPH
> Completer capability, and the ST fields of MSI-X entry.
>
> Introduce pcie_enable_tph() and pcie_disable_tph(), enabling drivers to
> toggle TPH support and configure specific ST mode as needed. Also add a
> new kernel parameter, "pci=notph", allowing users to disable TPH support
> across the entire system.
>
> Co-developed-by: Jing Liu <jing2.liu@...el.com>
> Signed-off-by: Jing Liu <jing2.liu@...el.com>
> Co-developed-by: Paul Luse <paul.e.luse@...ux.intel.com>
> Signed-off-by: Paul Luse <paul.e.luse@...ux.intel.com>
> Co-developed-by: Eric Van Tassell <Eric.VanTassell@....com>
> Signed-off-by: Eric Van Tassell <Eric.VanTassell@....com>
> Signed-off-by: Wei Huang <wei.huang2@....com>
> Reviewed-by: Ajit Khaparde <ajit.khaparde@...adcom.com>
> Reviewed-by: Somnath Kotur <somnath.kotur@...adcom.com>
> Reviewed-by: Andy Gospodarek <andrew.gospodarek@...adcom.com>
> Reviewed-by: Jonathan Cameron <Jonathan.Cameron@...wei.com>
> Reviewed-by: Lukas Wunner <lukas@...ner.de>
...
> diff --git a/drivers/pci/pcie/tph.c b/drivers/pci/pcie/tph.c
...
> +/**
> + * pcie_enable_tph - Enable TPH support for device using a specific ST mode
> + * @pdev: PCI device
> + * @mode: ST mode to enable. Current supported modes include:
> + *
> + * - PCI_TPH_ST_NS_MODE: NO ST Mode
> + * - PCI_TPH_ST_IV_MODE: Interrupt Vector Mode
> + * - PCI_TPH_ST_DS_MODE: Device Specific Mode
> + *
> + * Checks whether the mode is actually supported by the device before enabling
> + * and returns an error if not. Additionally determines what types of requests,
> + * TPH or extended TPH, can be issued by the device based on its TPH requester
> + * capability and the Root Port's completer capability.
> + *
> + * Return: 0 on success, otherwise negative value (-errno)
> + */
> +int pcie_enable_tph(struct pci_dev *pdev, int mode)
> +{
> + u32 reg;
> + u8 dev_modes;
> + u8 rp_req_type;
> +
> + /* Honor "notph" kernel parameter */
> + if (pci_tph_disabled)
> + return -EINVAL;
> +
> + if (!pdev->tph_cap)
> + return -EINVAL;
> +
> + if (pdev->tph_enabled)
> + return -EBUSY;
> +
> + /* Sanitize and check ST mode comptability */
Hi Wei Huang, all,
Another minor nit from my side (the last one, I think):
comptability -> compatibility
Flagged by checkpatch.pl --codespell
> + mode &= PCI_TPH_CTRL_MODE_SEL_MASK;
> + dev_modes = get_st_modes(pdev);
> + if (!((1 << mode) & dev_modes))
> + return -EINVAL;
> +
> + pdev->tph_mode = mode;
> +
> + /* Get req_type supported by device and its Root Port */
> + pci_read_config_dword(pdev, pdev->tph_cap + PCI_TPH_CAP, ®);
> + if (FIELD_GET(PCI_TPH_CAP_EXT_TPH, reg))
> + pdev->tph_req_type = PCI_TPH_REQ_EXT_TPH;
> + else
> + pdev->tph_req_type = PCI_TPH_REQ_TPH_ONLY;
> +
> + rp_req_type = get_rp_completer_type(pdev);
> +
> + /* Final req_type is the smallest value of two */
> + pdev->tph_req_type = min(pdev->tph_req_type, rp_req_type);
> +
> + if (pdev->tph_req_type == PCI_TPH_REQ_DISABLE)
> + return -EINVAL;
> +
> + /* Write them into TPH control register */
> + pci_read_config_dword(pdev, pdev->tph_cap + PCI_TPH_CTRL, ®);
> +
> + reg &= ~PCI_TPH_CTRL_MODE_SEL_MASK;
> + reg |= FIELD_PREP(PCI_TPH_CTRL_MODE_SEL_MASK, pdev->tph_mode);
> +
> + reg &= ~PCI_TPH_CTRL_REQ_EN_MASK;
> + reg |= FIELD_PREP(PCI_TPH_CTRL_REQ_EN_MASK, pdev->tph_req_type);
> +
> + pci_write_config_dword(pdev, pdev->tph_cap + PCI_TPH_CTRL, reg);
> +
> + pdev->tph_enabled = 1;
> +
> + return 0;
> +}
> +EXPORT_SYMBOL(pcie_enable_tph);
...
Powered by blists - more mailing lists