linux-kernel - RE: [PATCH v4 2/7] scsi: ufs-qcom: Add reset control support for host controller

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Date:   Thu, 14 Nov 2019 09:03:13 +0000
From:   Avri Altman <Avri.Altman@....com>
To:     Can Guo <cang@...eaurora.org>,
        "asutoshd@...eaurora.org" <asutoshd@...eaurora.org>,
        "nguyenb@...eaurora.org" <nguyenb@...eaurora.org>,
        "rnayak@...eaurora.org" <rnayak@...eaurora.org>,
        "linux-scsi@...r.kernel.org" <linux-scsi@...r.kernel.org>,
        "kernel-team@...roid.com" <kernel-team@...roid.com>,
        "saravanak@...gle.com" <saravanak@...gle.com>,
        "salyzyn@...gle.com" <salyzyn@...gle.com>
CC:     Andy Gross <agross@...nel.org>,
        Alim Akhtar <alim.akhtar@...sung.com>,
        Pedro Sousa <pedrom.sousa@...opsys.com>,
        "James E.J. Bottomley" <jejb@...ux.ibm.com>,
        "Martin K. Petersen" <martin.petersen@...cle.com>,
        "open list:ARM/QUALCOMM SUPPORT" <linux-arm-msm@...r.kernel.org>,
        open list <linux-kernel@...r.kernel.org>
Subject: RE: [PATCH v4 2/7] scsi: ufs-qcom: Add reset control support for host
 controller

Hi,

> 
> 
> Add reset control for host controller so that host controller can be reset as
> required in its power up sequence.
> 
> Signed-off-by: Can Guo <cang@...eaurora.org>
> +       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);
Aren't you sleeping anyway in your reset_control_ops?

> +
> +       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);
ditto