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Message-ID: <20230607164326.GA1167111@bhelgaas>
Date: Wed, 7 Jun 2023 11:43:26 -0500
From: Bjorn Helgaas <helgaas@...nel.org>
To: Krishna chaitanya chundru <quic_krichai@...cinc.com>
Cc: manivannan.sadhasivam@...aro.org, quic_vbadigan@...cinc.com,
quic_ramkri@...cinc.com, Manivannan Sadhasivam <mani@...nel.org>,
Lorenzo Pieralisi <lpieralisi@...nel.org>,
Krzysztof Wilczyński <kw@...ux.com>,
Rob Herring <robh@...nel.org>,
Bjorn Helgaas <bhelgaas@...gle.com>,
"open list:PCIE ENDPOINT DRIVER FOR QUALCOMM"
<linux-pci@...r.kernel.org>,
"open list:PCIE ENDPOINT DRIVER FOR QUALCOMM"
<linux-arm-msm@...r.kernel.org>,
open list <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH v2 3/3] PCI: qcom-ep: Add ICC bandwidth voting support
On Wed, Jun 07, 2023 at 09:48:07PM +0530, Krishna chaitanya chundru wrote:
> Add support to vote for ICC bandwidth based on the link
> speed and width.
>
> This patch is inspired from pcie-qcom driver to add basic
> interconnect support.
Wrap to fill 75 columns like the rest of the git history.
> Link:https://patchwork.kernel.org/project/linux-pci/patch/20221102090705.23634-3-johan+linaro@kernel.org/
Add space after "Link:"
Probably better to use a lore link
(https://lore.kernel.org/r/20221102090705.23634-3-johan+linaro@kernel.org/)
because I think lore is more general-purpose than patchwork and we
don't get any benefit from the patchwork features here.
> Signed-off-by: Krishna chaitanya chundru <quic_krichai@...cinc.com>
> ---
> drivers/pci/controller/dwc/pcie-qcom-ep.c | 68 +++++++++++++++++++++++++++++++
> 1 file changed, 68 insertions(+)
>
> diff --git a/drivers/pci/controller/dwc/pcie-qcom-ep.c b/drivers/pci/controller/dwc/pcie-qcom-ep.c
> index 19b3283..5f9139d 100644
> --- a/drivers/pci/controller/dwc/pcie-qcom-ep.c
> +++ b/drivers/pci/controller/dwc/pcie-qcom-ep.c
> @@ -13,6 +13,7 @@
> #include <linux/debugfs.h>
> #include <linux/delay.h>
> #include <linux/gpio/consumer.h>
> +#include <linux/interconnect.h>
> #include <linux/mfd/syscon.h>
> #include <linux/phy/pcie.h>
> #include <linux/phy/phy.h>
> @@ -28,6 +29,7 @@
> #define PARF_SYS_CTRL 0x00
> #define PARF_DB_CTRL 0x10
> #define PARF_PM_CTRL 0x20
> +#define PARF_PM_STTS 0x24
> #define PARF_MHI_CLOCK_RESET_CTRL 0x174
> #define PARF_MHI_BASE_ADDR_LOWER 0x178
> #define PARF_MHI_BASE_ADDR_UPPER 0x17c
> @@ -128,6 +130,9 @@
> /* DBI register fields */
> #define DBI_CON_STATUS_POWER_STATE_MASK GENMASK(1, 0)
>
> +#define DBI_LINKCTRLSTATUS 0x80
> +#define DBI_LINKCTRLSTATUS_SHIFT 16
> +
> #define XMLH_LINK_UP 0x400
> #define CORE_RESET_TIME_US_MIN 1000
> #define CORE_RESET_TIME_US_MAX 1005
> @@ -178,6 +183,8 @@ struct qcom_pcie_ep {
> struct phy *phy;
> struct dentry *debugfs;
>
> + struct icc_path *icc;
Seems gratuitously different from the "icc_mem" name used in
pcie-qcom. Use the same name unless there's a reason to be different.
> struct clk_bulk_data *clks;
> int num_clks;
>
> @@ -253,9 +260,51 @@ static void qcom_pcie_dw_stop_link(struct dw_pcie *pci)
> disable_irq(pcie_ep->perst_irq);
> }
>
> +static void qcom_pcie_ep_icc_update(struct qcom_pcie_ep *pcie_ep)
> +{
> + struct dw_pcie *pci = &pcie_ep->pci;
> + int speed, width;
> + u32 val, bw;
> + int ret;
> +
> + if (!pcie_ep->icc)
> + return;
> +
> + val = dw_pcie_readl_dbi(pci, DBI_LINKCTRLSTATUS);
> + val = val >> DBI_LINKCTRLSTATUS_SHIFT;
> +
> + speed = FIELD_GET(PCI_EXP_LNKSTA_CLS, val);
> + width = FIELD_GET(PCI_EXP_LNKSTA_NLW, val);
This whole function is basically identical to qcom_pcie_icc_update().
Could a single implementation be shared? qcom_pcie_icc_update() uses
dw_pcie_find_capability(pci, PCI_CAP_ID_EXP) instead of the hard-coded
DBI_LINKCTRLSTATUS, but there are other instances of
dw_pcie_find_capability() in pcie-qcom-ep.c, so it seems possible that
the same code could be used both places.
> + switch (speed) {
> + case 1:
> + bw = MBps_to_icc(250); /* BW for GEN1 per lane: 250MBps */
> + break;
> + case 2:
> + bw = MBps_to_icc(500); /* BW for GEN2 per lane: 500MBps */
> + break;
> + case 3:
> + bw = MBps_to_icc(985); /* BW for GEN3 per lane: 985MBps */
> + break;
> + default:
> + WARN_ON_ONCE(1);
> + fallthrough;
> + case 4:
> + bw = MBps_to_icc(1969); /* BW for GEN4 per lane: 985MBps */
> + break;
> + }
> +
> + ret = icc_set_bw(pcie_ep->icc, 0, width * bw);
> + if (ret) {
> + dev_err(pci->dev, "failed to set interconnect bandwidth: %d\n",
> + ret);
> + }
> +}
> +
> static int qcom_pcie_enable_resources(struct qcom_pcie_ep *pcie_ep)
> {
> int ret;
> + struct dw_pcie *pci = &pcie_ep->pci;
>
> ret = clk_bulk_prepare_enable(pcie_ep->num_clks, pcie_ep->clks);
> if (ret)
> @@ -277,6 +326,20 @@ static int qcom_pcie_enable_resources(struct qcom_pcie_ep *pcie_ep)
> if (ret)
> goto err_phy_exit;
>
> + /*
> + * Some Qualcomm platforms require interconnect bandwidth constraints
> + * to be set before enabling interconnect clocks.
> + *
> + * Set an initial average bandwidth corresponding to single-lane Gen 1
> + * for the pcie to mem path.
> + */
> + ret = icc_set_bw(pcie_ep->icc, 0, MBps_to_icc(250)); /* BW for GEN1 per lane: 250MBps */
Reformat the comment so this all fits in 80 columns like the rest of
the file.
> + if (ret) {
> + dev_err(pci->dev, "failed to set interconnect bandwidth: %d\n",
> + ret);
> + goto err_phy_exit;
> + }
This plus the pcie_ep->icc init below is basically identical to
qcom_pcie_icc_init() in pcie_qcom.c. Why not use the same structure
here, with a qcom_pcie_icc_init() function? It's better to be the
same than different (when possible, of course).
> return 0;
>
> err_phy_exit:
> @@ -550,6 +613,10 @@ static int qcom_pcie_ep_get_resources(struct platform_device *pdev,
> if (IS_ERR(pcie_ep->phy))
> ret = PTR_ERR(pcie_ep->phy);
>
> + pcie_ep->icc = devm_of_icc_get(dev, "pcie-mem");
> + if (IS_ERR(pcie_ep->icc))
> + ret = PTR_ERR(pcie_ep->icc);
> +
> return ret;
> }
>
> @@ -572,6 +639,7 @@ static irqreturn_t qcom_pcie_ep_global_irq_thread(int irq, void *data)
> } else if (FIELD_GET(PARF_INT_ALL_BME, status)) {
> dev_dbg(dev, "Received BME event. Link is enabled!\n");
> pcie_ep->link_status = QCOM_PCIE_EP_LINK_ENABLED;
> + qcom_pcie_ep_icc_update(pcie_ep);
> } else if (FIELD_GET(PARF_INT_ALL_PM_TURNOFF, status)) {
> dev_dbg(dev, "Received PM Turn-off event! Entering L23\n");
> val = readl_relaxed(pcie_ep->parf + PARF_PM_CTRL);
> --
> 2.7.4
>
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