Re: [PATCH v5 2/7] scsi: ufs-qcom: Add reset control support for host controller

[Jeffrey Hugo <jeffrey.l.hugo@gmail.com>]

On Mon, Dec 16, 2019 at 12:05 PM Vinod Koul <vkoul@kernel.org> wrote:
>
> Hi Can,
>
> On 14-11-19, 22:09, Can Guo wrote:
> > Add reset control for host controller so that host controller can be reset
> > as required in its power up sequence.
>
> I am seeing a regression on UFS on SM8150-mtp with this patch. I think
> Jeff is seeing same one lenove laptop on 8998.

Confirmed.

>
> 845 does not seem to have this issue and only thing I can see is that on
> sm8150 and 8998 we define reset as:
>
>                         resets = <&gcc GCC_UFS_BCR>;
>                         reset-names = "rst";
>
> Thanks
>
> >
> > Signed-off-by: Can Guo <cang@codeaurora.org>
> > ---
> >  drivers/scsi/ufs/ufs-qcom.c | 53 +++++++++++++++++++++++++++++++++++++++++++++
> >  drivers/scsi/ufs/ufs-qcom.h |  3 +++
> >  2 files changed, 56 insertions(+)
> >
> > diff --git a/drivers/scsi/ufs/ufs-qcom.c b/drivers/scsi/ufs/ufs-qcom.c
> > index a5b7148..c69c29a1c 100644
> > --- a/drivers/scsi/ufs/ufs-qcom.c
> > +++ b/drivers/scsi/ufs/ufs-qcom.c
> > @@ -246,6 +246,44 @@ static void ufs_qcom_select_unipro_mode(struct ufs_qcom_host *host)
> >       mb();
> >  }
> >
> > +/**
> > + * ufs_qcom_host_reset - reset host controller and PHY
> > + */
> > +static int ufs_qcom_host_reset(struct ufs_hba *hba)
> > +{
> > +     int ret = 0;
> > +     struct ufs_qcom_host *host = ufshcd_get_variant(hba);
> > +
> > +     if (!host->core_reset) {
> > +             dev_warn(hba->dev, "%s: reset control not set\n", __func__);
> > +             goto out;
> > +     }
> > +
> > +     ret = reset_control_assert(host->core_reset);
> > +     if (ret) {
> > +             dev_err(hba->dev, "%s: core_reset assert failed, err = %d\n",
> > +                              __func__, ret);
> > +             goto out;
> > +     }
> > +
> > +     /*
> > +      * The hardware requirement for delay between assert/deassert
> > +      * is at least 3-4 sleep clock (32.7KHz) cycles, which comes to
> > +      * ~125us (4/32768). To be on the safe side add 200us delay.
> > +      */
> > +     usleep_range(200, 210);
> > +
> > +     ret = reset_control_deassert(host->core_reset);
> > +     if (ret)
> > +             dev_err(hba->dev, "%s: core_reset deassert failed, err = %d\n",
> > +                              __func__, ret);
> > +
> > +     usleep_range(1000, 1100);
> > +
> > +out:
> > +     return ret;
> > +}
> > +
> >  static int ufs_qcom_power_up_sequence(struct ufs_hba *hba)
> >  {
> >       struct ufs_qcom_host *host = ufshcd_get_variant(hba);
> > @@ -254,6 +292,12 @@ static int ufs_qcom_power_up_sequence(struct ufs_hba *hba)
> >       bool is_rate_B = (UFS_QCOM_LIMIT_HS_RATE == PA_HS_MODE_B)
> >                                                       ? true : false;
> >
> > +     /* Reset UFS Host Controller and PHY */
> > +     ret = ufs_qcom_host_reset(hba);
> > +     if (ret)
> > +             dev_warn(hba->dev, "%s: host reset returned %d\n",
> > +                               __func__, ret);
> > +
> >       if (is_rate_B)
> >               phy_set_mode(phy, PHY_MODE_UFS_HS_B);
> >
> > @@ -1101,6 +1145,15 @@ static int ufs_qcom_init(struct ufs_hba *hba)
> >       host->hba = hba;
> >       ufshcd_set_variant(hba, host);
> >
> > +     /* Setup the reset control of HCI */
> > +     host->core_reset = devm_reset_control_get(hba->dev, "rst");
> > +     if (IS_ERR(host->core_reset)) {
> > +             err = PTR_ERR(host->core_reset);
> > +             dev_warn(dev, "Failed to get reset control %d\n", err);
> > +             host->core_reset = NULL;
> > +             err = 0;
> > +     }
> > +
> >       /* Fire up the reset controller. Failure here is non-fatal. */
> >       host->rcdev.of_node = dev->of_node;
> >       host->rcdev.ops = &ufs_qcom_reset_ops;
> > diff --git a/drivers/scsi/ufs/ufs-qcom.h b/drivers/scsi/ufs/ufs-qcom.h
> > index d401f17..2d95e7c 100644
> > --- a/drivers/scsi/ufs/ufs-qcom.h
> > +++ b/drivers/scsi/ufs/ufs-qcom.h
> > @@ -6,6 +6,7 @@
> >  #define UFS_QCOM_H_
> >
> >  #include <linux/reset-controller.h>
> > +#include <linux/reset.h>
> >
> >  #define MAX_UFS_QCOM_HOSTS   1
> >  #define MAX_U32                 (~(u32)0)
> > @@ -233,6 +234,8 @@ struct ufs_qcom_host {
> >       u32 dbg_print_en;
> >       struct ufs_qcom_testbus testbus;
> >
> > +     /* Reset control of HCI */
> > +     struct reset_control *core_reset;
> >       struct reset_controller_dev rcdev;
> >
> >       struct gpio_desc *device_reset;
> > --
> > The Qualcomm Innovation Center, Inc. is a member of the Code Aurora Forum,
> > a Linux Foundation Collaborative Project
>
> --
> ~Vinod