linux-kernel - Re: [PATCH v3 2/2] scsi: ufs-qcom: enter and exit hibern8 during clock scaling

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Date:   Wed, 20 May 2020 09:55:43 -0700
From:   "Asutosh Das (asd)" <asutoshd@...eaurora.org>
To:     Pedro Sousa <PedroM.Sousa@...opsys.com>,
        "cang@...eaurora.org" <cang@...eaurora.org>,
        "rnayak@...eaurora.org" <rnayak@...eaurora.org>,
        "vinholikatti@...il.com" <vinholikatti@...il.com>,
        "jejb@...ux.vnet.ibm.com" <jejb@...ux.vnet.ibm.com>,
        "martin.petersen@...cle.com" <martin.petersen@...cle.com>
Cc:     "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>,
        Andy Gross <agross@...nel.org>,
        Alim Akhtar <alim.akhtar@...sung.com>,
        Avri Altman <avri.altman@....com>,
        "James E.J. Bottomley" <jejb@...ux.ibm.com>,
        "open list:ARM/QUALCOMM SUPPORT" <linux-arm-msm@...r.kernel.org>,
        open list <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH v3 2/2] scsi: ufs-qcom: enter and exit hibern8 during
 clock scaling

Hi Pedro,

On 11/11/2019 7:54 AM, Pedro Sousa wrote:
> Hi Asutosh,
> 
> Please check comments.
Sorry for missing out on this and thanks for your review.

> 
> -----Original Message-----
> From: Asutosh Das <asutoshd@...eaurora.org>
> Sent: Wednesday, October 23, 2019 5:49 PM
> To: cang@...eaurora.org; rnayak@...eaurora.org; vinholikatti@...il.com; jejb@...ux.vnet.ibm.com; martin.petersen@...cle.com
> Cc: linux-scsi@...r.kernel.org; kernel-team@...roid.com; saravanak@...gle.com; salyzyn@...gle.com; Asutosh Das <asutoshd@...eaurora.org>; Andy Gross <agross@...nel.org>; Alim Akhtar <alim.akhtar@...sung.com>; Avri Altman <avri.altman@....com>; Pedro Sousa <pedrom.sousa@...opsys.com>; James E.J. Bottomley <jejb@...ux.ibm.com>; open list:ARM/QUALCOMM SUPPORT <linux-arm-msm@...r.kernel.org>; open list <linux-kernel@...r.kernel.org>
> Subject: [PATCH v3 2/2] scsi: ufs-qcom: enter and exit hibern8 during clock scaling
> 
> Qualcomm controller needs to be in hibern8 before scaling clocks.
> This change puts the controller in hibern8 state before scaling
> and brings it out after scaling of clocks.
> 
> Signed-off-by: Asutosh Das <asutoshd@...eaurora.org>
> ---
>   drivers/scsi/ufs/ufs-qcom.c | 12 +++++++++++-
>   1 file changed, 11 insertions(+), 1 deletion(-)
> 
> diff --git a/drivers/scsi/ufs/ufs-qcom.c b/drivers/scsi/ufs/ufs-qcom.c
> index a5b7148..55b1de5 100644
> --- a/drivers/scsi/ufs/ufs-qcom.c
> +++ b/drivers/scsi/ufs/ufs-qcom.c
> @@ -1305,18 +1305,27 @@ static int ufs_qcom_clk_scale_notify(struct ufs_hba *hba,
>   	int err = 0;
>   
>   	if (status == PRE_CHANGE) {
> +		err = ufshcd_uic_hibern8_enter(hba);
> +		if (err)
> +			return err;
>   		if (scale_up)
>   			err = ufs_qcom_clk_scale_up_pre_change(hba);
>   		else
>   			err = ufs_qcom_clk_scale_down_pre_change(hba);
> +		if (err)
> +			ufshcd_uic_hibern8_exit(hba);
> +
>   	} else {
>   		if (scale_up)
>   			err = ufs_qcom_clk_scale_up_post_change(hba);
>   		else
>   			err = ufs_qcom_clk_scale_down_post_change(hba);
>   
> -		if (err || !dev_req_params)
> +
> +		if (err || !dev_req_params) {
> +			ufshcd_uic_hibern8_exit(hba);
>   			goto out;
> +		}
>   
>   		ufs_qcom_cfg_timers(hba,
>   				    dev_req_params->gear_rx,
> @@ -1324,6 +1333,7 @@ static int ufs_qcom_clk_scale_notify(struct ufs_hba *hba,
>   				    dev_req_params->hs_rate,
>   				    false);
>   		ufs_qcom_update_bus_bw_vote(host);
> +		ufshcd_uic_hibern8_exit(hba);
> 
> Here you are creating the possibility of returning a success even if hibern8 exit fails.
> If hibern8 exit fails the ufs recovery will be triggered and "err" variable will not get updated
> in this function, how is this handled? Did you tested this possibility?
> 
>   	}
>   
>   out:
> 


Yes - I agree with your comment. The error should be propagated from 
this function correctly to the caller. I'll push another version.

-- 
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