linux-kernel - Re: [PATCH v2] scsi: ufs: disable auto hibern8 while entering suspend

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Date:   Wed, 26 Jan 2022 09:22:28 +0800
From:   Stanley Chu <stanley.chu@...iatek.com>
To:     SEO HOYOUNG <hy50.seo@...sung.com>, <linux-scsi@...r.kernel.org>,
        <linux-kernel@...r.kernel.org>, <alim.akhtar@...sung.com>,
        <avri.altman@....com>, <jejb@...ux.ibm.com>,
        <martin.petersen@...cle.com>, <beanhuo@...ron.com>,
        <asutoshd@...eaurora.org>, <cang@...eaurora.org>,
        <bvanassche@....org>, <bhoon95.kim@...sung.com>,
        <kwmad.kim@...sung.com>
CC:     kernel test robot <lkp@...el.com>, <peter.wang@...iatek.com>
Subject: Re: [PATCH v2] scsi: ufs: disable auto hibern8 while entering
 suspend

Hi Hoyoung,

On Tue, 2022-01-25 at 03:06 +0900, SEO HOYOUNG wrote:
> v1-> v2: fixed no previous prototype warning
> Reported-by: kernel test robot <lkp@...el.com>
> 
> All warnings (new ones prefixed by >>):
> > > drivers/scsi/ufs/ufshcd.c:4207:6: warning: no previous prototype 
> 
> for 'ufshcd_auto_hibern8_disable' [-Wmissing-prototypes]
> 4207 | void ufshcd_auto_hibern8_disable(struct ufs_hba *hba)
> 
> If using auto hibern8 mode, need to disable auto hibern8 while
> entering suspend.
> When using auto hibern8 mode, it does not seem right to send a uic
> command

The UFSHCI spec does not mention the above rule.
Why would you need to disable AH8 before using UIC command to enter H8?

> for entry into hibern8 in the next
> line(ufshcd_lik_state_transition(..))
> It seem right to send after disable auto hibern8.
> 
> In addition, if the auto hibern8 mode supported, it is enabled in
> resume.
> So it seems that it will be paired only when auto hibern8 is disabled
> while entering suspend.
> 
> Signed-off-by: SEO HOYOUNG <hy50.seo@...sung.com>
> ---
>  drivers/scsi/ufs/ufshcd.c | 14 ++++++++++++++
>  1 file changed, 14 insertions(+)
> 
> diff --git a/drivers/scsi/ufs/ufshcd.c b/drivers/scsi/ufs/ufshcd.c
> index 460d2b440d2e..a6edbbd8ca2c 100644
> --- a/drivers/scsi/ufs/ufshcd.c
> +++ b/drivers/scsi/ufs/ufshcd.c
> @@ -254,6 +254,7 @@ static void
> ufshcd_wb_toggle_flush_during_h8(struct ufs_hba *hba, bool set);
>  static inline void ufshcd_wb_toggle_flush(struct ufs_hba *hba, bool
> enable);
>  static void ufshcd_hba_vreg_set_lpm(struct ufs_hba *hba);
>  static void ufshcd_hba_vreg_set_hpm(struct ufs_hba *hba);
> +static void ufshcd_auto_hibern8_disable(struct ufs_hba *hba);
>  
>  static inline void ufshcd_enable_irq(struct ufs_hba *hba)
>  {
> @@ -4204,6 +4205,18 @@ void ufshcd_auto_hibern8_update(struct ufs_hba
> *hba, u32 ahit)
>  }
>  EXPORT_SYMBOL_GPL(ufshcd_auto_hibern8_update);
>  
> +static void ufshcd_auto_hibern8_disable(struct ufs_hba *hba)
> +{
> +	unsigned long flags;
> +
> +	if (!ufshcd_is_auto_hibern8_supported(hba))
> +		return;
> +
> +	spin_lock_irqsave(hba->host->host_lock, flags);
> +	ufshcd_writel(hba, 0, REG_AUTO_HIBERNATE_IDLE_TIMER);
> +	spin_unlock_irqrestore(hba->host->host_lock, flags);
> +}
> +
>  void ufshcd_auto_hibern8_enable(struct ufs_hba *hba)
>  {
>  	unsigned long flags;
> @@ -8925,6 +8938,7 @@ static int __ufshcd_wl_suspend(struct ufs_hba
> *hba, enum ufs_pm_op pm_op)
>  	 * with the link off, so do not check for bkops.
>  	 */
>  	check_for_bkops = !ufshcd_is_ufs_dev_deepsleep(hba);
> +	ufshcd_auto_hibern8_disable(hba);
>  	ret = ufshcd_link_state_transition(hba, req_link_state,
> check_for_bkops);
>  	if (ret)
>  		goto set_dev_active;