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Message-ID: <fe0f836a-0710-28dc-41a2-5144c9e11875@quicinc.com>
Date: Fri, 9 Jun 2023 17:20:28 +0530
From: Krishna Chaitanya Chundru <quic_krichai@...cinc.com>
To: Bjorn Helgaas <helgaas@...nel.org>
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 6/7/2023 10:13 PM, Bjorn Helgaas wrote:
> 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.
done
>> 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.
done
>> 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.
done
>> + 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.
done
>> + 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).
In pcie_qcom.c driver the resources will be turned on the probe itself.
But in pcie-qcom-ep.c driver will wait for the host to toggle the perst
to enable all the resources
that is reason it is different here.
- Krishna chaitanya.
>> 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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