RE: [PATCH] scsi: ufs-pci: Add LTR support for Intel controllers

[Avri Altman]

> 
> Intel host controllers support the setting of latency tolerance.
> Accordingly, implement the PM QoS ->set_latency_tolerance() callback. The
> raw register values are also exposed via debugfs.
> 
> Signed-off-by: Adrian Hunter <adrian.hunter@xxxxxxxxx>
Reviewed-by: Avri Altman <avri.altman@xxxxxxx>

Some nits below.

Thanks,
Avri

> ---
>  drivers/scsi/ufs/ufshcd-pci.c | 122 +++++++++++++++++++++++++++++++++-
>  1 file changed, 120 insertions(+), 2 deletions(-)
> 
> diff --git a/drivers/scsi/ufs/ufshcd-pci.c b/drivers/scsi/ufs/ufshcd-pci.c
> index 5a95a7bfbab0..e10f05013ae6 100644
> --- a/drivers/scsi/ufs/ufshcd-pci.c
> +++ b/drivers/scsi/ufs/ufshcd-pci.c
> @@ -13,6 +13,14 @@
>  #include "ufshcd.h"
>  #include <linux/pci.h>
>  #include <linux/pm_runtime.h>
> +#include <linux/pm_qos.h>
> +#include <linux/debugfs.h>
> +
> +struct intel_host {
> +       u32             active_ltr;
> +       u32             idle_ltr;
> +       struct dentry   *debugfs_root;
> +};
> 
>  static int ufs_intel_disable_lcc(struct ufs_hba *hba)
>  {
> @@ -44,20 +52,129 @@ static int ufs_intel_link_startup_notify(struct ufs_hba
> *hba,
>         return err;
>  }
> 
> +#define INTEL_ACTIVELTR                0x804
> +#define INTEL_IDLELTR          0x808
> +
> +#define INTEL_LTR_REQ          BIT(15)
> +#define INTEL_LTR_SCALE_MASK   GENMASK(11, 10)
> +#define INTEL_LTR_SCALE_1US    (2 << 10)
> +#define INTEL_LTR_SCALE_32US   (3 << 10)
> +#define INTEL_LTR_VALUE_MASK   GENMASK(9, 0)
> +
> +static void intel_cache_ltr(struct ufs_hba *hba)
> +{
> +       struct intel_host *host = ufshcd_get_variant(hba);
> +
> +       host->active_ltr = readl(hba->mmio_base + INTEL_ACTIVELTR);
> +       host->idle_ltr = readl(hba->mmio_base + INTEL_IDLELTR);
You might want to use the standard ufshcd_readl

> +}
> +
> +static void intel_ltr_set(struct device *dev, s32 val)
> +{
> +       struct ufs_hba *hba = dev_get_drvdata(dev);
> +       struct intel_host *host = ufshcd_get_variant(hba);
> +       u32 ltr;
> +
> +       pm_runtime_get_sync(dev);
> +
> +       /*
> +        * Program latency tolerance (LTR) accordingly what has been asked
> +        * by the PM QoS layer or disable it in case we were passed
> +        * negative value or PM_QOS_LATENCY_ANY.
> +        */
> +       ltr = readl(hba->mmio_base + INTEL_ACTIVELTR);
> +
> +       if (val == PM_QOS_LATENCY_ANY || val < 0) {
> +               ltr &= ~INTEL_LTR_REQ;
> +       } else {
> +               ltr |= INTEL_LTR_REQ;
> +               ltr &= ~INTEL_LTR_SCALE_MASK;
> +               ltr &= ~INTEL_LTR_VALUE_MASK;
> +
> +               if (val > INTEL_LTR_VALUE_MASK) {
> +                       val >>= 5;
> +                       if (val > INTEL_LTR_VALUE_MASK)
> +                               val = INTEL_LTR_VALUE_MASK;
> +                       ltr |= INTEL_LTR_SCALE_32US | val;
> +               } else {
> +                       ltr |= INTEL_LTR_SCALE_1US | val;
> +               }
> +       }
> +
> +       if (ltr == host->active_ltr)
> +               goto out;
> +
> +       writel(ltr, hba->mmio_base + INTEL_ACTIVELTR);
> +       writel(ltr, hba->mmio_base + INTEL_IDLELTR);
> +
> +       /* Cache the values into intel_host structure */
> +       intel_cache_ltr(hba);
> +out:
> +       pm_runtime_put(dev);
> +}
> +
> +static void ufs_intel_ltr_expose(struct ufs_hba *hba)
> +{
> +       struct intel_host *host = ufshcd_get_variant(hba);
> +       struct dentry *dir = host->debugfs_root;
> +       struct device *dev = hba->dev;
> +
> +       dev->power.set_latency_tolerance = intel_ltr_set;
> +       dev_pm_qos_expose_latency_tolerance(dev);
> +
> +       intel_cache_ltr(hba);
> +
> +       debugfs_create_x32("active_ltr", 0444, dir, &host->active_ltr);
> +       debugfs_create_x32("idle_ltr", 0444, dir, &host->idle_ltr);
You might as well allow those values to be traced, e.g. use dev_pm_qos_update_user_latency_tolerance

> +}
> +
> +static void ufs_intel_ltr_hide(struct ufs_hba *hba)
> +{
> +       struct device *dev = hba->dev;
> +
> +       dev_pm_qos_hide_latency_tolerance(dev);
> +       dev->power.set_latency_tolerance = NULL;
> +}
> +
> +static int ufs_intel_common_init(struct ufs_hba *hba)
> +{
> +       struct device *dev = hba->dev;
> +       struct intel_host *host;
> +
> +       host = devm_kzalloc(dev, sizeof(*host), GFP_KERNEL);
> +       if (!host)
> +               return -ENOMEM;
> +       ufshcd_set_variant(hba, host);
> +       host->debugfs_root = debugfs_create_dir(dev_name(dev), NULL);
Maybe pack the debugfs code together, i.e. move this just above debugfs_create_x32 ....

> +       ufs_intel_ltr_expose(hba);
> +       return 0;
> +}
> +
> +static void ufs_intel_common_exit(struct ufs_hba *hba)
> +{
> +       struct intel_host *host = ufshcd_get_variant(hba);
> +
> +       debugfs_remove_recursive(host->debugfs_root);
> +       ufs_intel_ltr_hide(hba);
> +}
> +
>  static int ufs_intel_ehl_init(struct ufs_hba *hba)
>  {
>         hba->quirks |= UFSHCD_QUIRK_BROKEN_AUTO_HIBERN8;
> -       return 0;
> +       return ufs_intel_common_init(hba);
>  }
> 
>  static struct ufs_hba_variant_ops ufs_intel_cnl_hba_vops = {
>         .name                   = "intel-pci",
> +       .init                   = ufs_intel_common_init,
> +       .exit                   = ufs_intel_common_exit,
>         .link_startup_notify    = ufs_intel_link_startup_notify,
>  };
> 
>  static struct ufs_hba_variant_ops ufs_intel_ehl_hba_vops = {
>         .name                   = "intel-pci",
>         .init                   = ufs_intel_ehl_init,
> +       .exit                   = ufs_intel_common_exit,
>         .link_startup_notify    = ufs_intel_link_startup_notify,
>  };
> 
> @@ -162,6 +279,8 @@ ufshcd_pci_probe(struct pci_dev *pdev, const struct
> pci_device_id *id)
>                 return err;
>         }
> 
> +       pci_set_drvdata(pdev, hba);
> +
>         hba->vops = (struct ufs_hba_variant_ops *)id->driver_data;
> 
>         err = ufshcd_init(hba, mmio_base, pdev->irq);
> @@ -171,7 +290,6 @@ ufshcd_pci_probe(struct pci_dev *pdev, const struct
> pci_device_id *id)
>                 return err;
>         }
> 
> -       pci_set_drvdata(pdev, hba);
>         pm_runtime_put_noidle(&pdev->dev);
>         pm_runtime_allow(&pdev->dev);
> 
> --
> 2.17.1