linux-kernel - Re: [PATCH v2 05/10] scsi: ufshcd: fix possible unclocked register access

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Date:   Wed, 16 May 2018 14:12:33 -0700
From:   Subhash Jadavani <subhashj@...eaurora.org>
To:     Asutosh Das <asutoshd@...eaurora.org>
Cc:     cang@...eaurora.org, vivek.gautam@...eaurora.org,
        rnayak@...eaurora.org, vinholikatti@...il.com,
        jejb@...ux.vnet.ibm.com, martin.petersen@...cle.com,
        linux-mmc@...r.kernel.org, linux-scsi@...r.kernel.org,
        linux-arm-msm@...r.kernel.org,
        Venkat Gopalakrishnan <venkatg@...eaurora.org>,
        linux-kernel@...r.kernel.org, linux-scsi-owner@...r.kernel.org
Subject: Re: [PATCH v2 05/10] scsi: ufshcd: fix possible unclocked register
 access

On 2018-05-03 04:07, Asutosh Das wrote:
> From: Subhash Jadavani <subhashj@...eaurora.org>
> 
> vendor specific setup_clocks ops may depend on clocks managed by ufshcd
> driver so if the vendor specific setup_clocks callback is called when
> the required clocks are turned off, it results into unclocked register
> access.
> 
> This change make sure that required clocks are enabled before vendor
> specific setup_clocks callback is called.
> 
> Signed-off-by: Subhash Jadavani <subhashj@...eaurora.org>
> Signed-off-by: Venkat Gopalakrishnan <venkatg@...eaurora.org>
> Signed-off-by: Can Guo <cang@...eaurora.org>
> Signed-off-by: Asutosh Das <asutoshd@...eaurora.org>
> ---
>  drivers/scsi/ufs/ufshcd.c | 26 ++++++++++++++++++++------
>  1 file changed, 20 insertions(+), 6 deletions(-)
> 
> diff --git a/drivers/scsi/ufs/ufshcd.c b/drivers/scsi/ufs/ufshcd.c
> index 838ba8f0..dfeb194 100644
> --- a/drivers/scsi/ufs/ufshcd.c
> +++ b/drivers/scsi/ufs/ufshcd.c
> @@ -6780,9 +6780,16 @@ static int __ufshcd_setup_clocks(struct ufs_hba
> *hba, bool on,
>  	if (list_empty(head))
>  		goto out;
> 
> -	ret = ufshcd_vops_setup_clocks(hba, on, PRE_CHANGE);
> -	if (ret)
> -		return ret;
> +	/*
> +	 * vendor specific setup_clocks ops may depend on clocks managed by
> +	 * this standard driver hence call the vendor specific setup_clocks
> +	 * before disabling the clocks managed here.
> +	 */
> +	if (!on) {
> +		ret = ufshcd_vops_setup_clocks(hba, on, PRE_CHANGE);
> +		if (ret)
> +			return ret;
> +	}
> 
>  	list_for_each_entry(clki, head, list) {
>  		if (!IS_ERR_OR_NULL(clki->clk)) {
> @@ -6806,9 +6813,16 @@ static int __ufshcd_setup_clocks(struct ufs_hba
> *hba, bool on,
>  		}
>  	}
> 
> -	ret = ufshcd_vops_setup_clocks(hba, on, POST_CHANGE);
> -	if (ret)
> -		return ret;
> +	/*
> +	 * vendor specific setup_clocks ops may depend on clocks managed by
> +	 * this standard driver hence call the vendor specific setup_clocks
> +	 * after enabling the clocks managed here.
> +	 */
> +	if (on) {
> +		ret = ufshcd_vops_setup_clocks(hba, on, POST_CHANGE);
> +		if (ret)
> +			return ret;
> +	}
> 
>  out:
>  	if (ret) {

Looks good to me.

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