linux-kernel - Re: [PATCH V4 2/2] scsi: ufs: Allow an error return value from ->device

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Date:   Wed, 4 Nov 2020 10:55:27 +0800
From:   Stanley Chu <stanley.chu@...iatek.com>
To:     Adrian Hunter <adrian.hunter@...el.com>
CC:     "Martin K . Petersen" <martin.petersen@...cle.com>,
        "James E . J . Bottomley" <jejb@...ux.ibm.com>,
        <linux-scsi@...r.kernel.org>, <linux-kernel@...r.kernel.org>,
        Alim Akhtar <alim.akhtar@...sung.com>,
        "Avri Altman" <avri.altman@....com>, Bean Huo <huobean@...il.com>,
        Can Guo <cang@...eaurora.org>
Subject: Re: [PATCH V4 2/2] scsi: ufs: Allow an error return value from
 ->device_reset()

Hi Adrian,

On Tue, 2020-11-03 at 16:14 +0200, Adrian Hunter wrote:
> It is simpler for drivers to provide a ->device_reset() callback
> irrespective of whether the GPIO, or firmware interface necessary to do the
> reset, is discovered during probe.
> 
> Change ->device_reset() to return an error code.  Drivers that provide
> the callback, but do not do the reset operation should return -EOPNOTSUPP.
> 
> Signed-off-by: Adrian Hunter <adrian.hunter@...el.com>
> ---
>  drivers/scsi/ufs/ufs-mediatek.c |  4 +++-
>  drivers/scsi/ufs/ufs-qcom.c     |  6 ++++--
>  drivers/scsi/ufs/ufshcd.h       | 11 +++++++----
>  3 files changed, 14 insertions(+), 7 deletions(-)
> 
> diff --git a/drivers/scsi/ufs/ufs-mediatek.c b/drivers/scsi/ufs/ufs-mediatek.c
> index 8df73bc2f8cb..914a827a93ee 100644
> --- a/drivers/scsi/ufs/ufs-mediatek.c
> +++ b/drivers/scsi/ufs/ufs-mediatek.c
> @@ -743,7 +743,7 @@ static int ufs_mtk_link_startup_notify(struct ufs_hba *hba,
>  	return ret;
>  }
>  
> -static void ufs_mtk_device_reset(struct ufs_hba *hba)
> +static int ufs_mtk_device_reset(struct ufs_hba *hba)
>  {
>  	struct arm_smccc_res res;
>  
> @@ -764,6 +764,8 @@ static void ufs_mtk_device_reset(struct ufs_hba *hba)
>  	usleep_range(10000, 15000);
>  
>  	dev_info(hba->dev, "device reset done\n");
> +
> +	return 0;
>  }
>  
>  static int ufs_mtk_link_set_hpm(struct ufs_hba *hba)
> diff --git a/drivers/scsi/ufs/ufs-qcom.c b/drivers/scsi/ufs/ufs-qcom.c
> index 9a19c6d15d3b..357c3b49321d 100644
> --- a/drivers/scsi/ufs/ufs-qcom.c
> +++ b/drivers/scsi/ufs/ufs-qcom.c
> @@ -1422,13 +1422,13 @@ static void ufs_qcom_dump_dbg_regs(struct ufs_hba *hba)
>   *
>   * Toggles the (optional) reset line to reset the attached device.
>   */
> -static void ufs_qcom_device_reset(struct ufs_hba *hba)
> +static int ufs_qcom_device_reset(struct ufs_hba *hba)
>  {
>  	struct ufs_qcom_host *host = ufshcd_get_variant(hba);
>  
>  	/* reset gpio is optional */
>  	if (!host->device_reset)
> -		return;
> +		return -EOPNOTSUPP;
>  
>  	/*
>  	 * The UFS device shall detect reset pulses of 1us, sleep for 10us to
> @@ -1439,6 +1439,8 @@ static void ufs_qcom_device_reset(struct ufs_hba *hba)
>  
>  	gpiod_set_value_cansleep(host->device_reset, 0);
>  	usleep_range(10, 15);
> +
> +	return 0;
>  }
>  
>  #if IS_ENABLED(CONFIG_DEVFREQ_GOV_SIMPLE_ONDEMAND)
> diff --git a/drivers/scsi/ufs/ufshcd.h b/drivers/scsi/ufs/ufshcd.h
> index 213be0667b59..5191d87f6263 100644
> --- a/drivers/scsi/ufs/ufshcd.h
> +++ b/drivers/scsi/ufs/ufshcd.h
> @@ -323,7 +323,7 @@ struct ufs_hba_variant_ops {
>  	int     (*resume)(struct ufs_hba *, enum ufs_pm_op);
>  	void	(*dbg_register_dump)(struct ufs_hba *hba);
>  	int	(*phy_initialization)(struct ufs_hba *);
> -	void	(*device_reset)(struct ufs_hba *hba);
> +	int	(*device_reset)(struct ufs_hba *hba);
>  	void	(*config_scaling_param)(struct ufs_hba *hba,
>  					struct devfreq_dev_profile *profile,
>  					void *data);
> @@ -1207,9 +1207,12 @@ static inline void ufshcd_vops_dbg_register_dump(struct ufs_hba *hba)
>  static inline void ufshcd_vops_device_reset(struct ufs_hba *hba)
>  {
>  	if (hba->vops && hba->vops->device_reset) {
> -		hba->vops->device_reset(hba);
> -		ufshcd_set_ufs_dev_active(hba);
> -		ufshcd_update_reg_hist(&hba->ufs_stats.dev_reset, 0);
> +		int err = hba->vops->device_reset(hba);
> +
> +		if (!err)
> +			ufshcd_set_ufs_dev_active(hba);
> +		if (err != -EOPNOTSUPP)
> +			ufshcd_update_reg_hist(&hba->ufs_stats.dev_reset, err);
>  	}
>  }

For ufs-mediatek part and related flow,

Reviewed-by: Stanley Chu <stanley.chu@...iatek.com>