Re: [PATCH v4 7/8] scsi: ufs-qcom: Delay specific time before gate ref clk

[Asutosh Das (asd)]

On 1/22/2020 11:25 PM, Can Guo wrote:
> After enter hibern8, as UFS JEDEC ver 3.0 requires, a specific gating wait
> time is required before disable the device reference clock. If it is not
> specified, use the old delay.
>
> Signed-off-by: Can Guo <cang@xxxxxxxxxxxxxx>
> ---

Reviewed-by: Asutosh Das <asutoshd@xxxxxxxxxxxxxx>

>   drivers/scsi/ufs/ufs-qcom.c | 13 ++++++++++---
>   1 file changed, 10 insertions(+), 3 deletions(-)
>
> diff --git a/drivers/scsi/ufs/ufs-qcom.c b/drivers/scsi/ufs/ufs-qcom.c
> index 85d7c17..3b5b2d9 100644
> --- a/drivers/scsi/ufs/ufs-qcom.c
> +++ b/drivers/scsi/ufs/ufs-qcom.c
> @@ -833,6 +833,8 @@ static int ufs_qcom_bus_register(struct ufs_qcom_host *host)
>   
>   static void ufs_qcom_dev_ref_clk_ctrl(struct ufs_qcom_host *host, bool enable)
>   {
> +	unsigned long gating_wait;
> +
>   	if (host->dev_ref_clk_ctrl_mmio &&
>   	    (enable ^ host->is_dev_ref_clk_enabled)) {
>   		u32 temp = readl_relaxed(host->dev_ref_clk_ctrl_mmio);
> @@ -845,11 +847,16 @@ static void ufs_qcom_dev_ref_clk_ctrl(struct ufs_qcom_host *host, bool enable)
>   		/*
>   		 * If we are here to disable this clock it might be immediately
>   		 * after entering into hibern8 in which case we need to make
> -		 * sure that device ref_clk is active at least 1us after the
> +		 * sure that device ref_clk is active for specific time after
>   		 * hibern8 enter.
>   		 */
> -		if (!enable)
> -			udelay(1);
> +		if (!enable) {
> +			gating_wait = host->hba->dev_info.clk_gating_wait_us;
> +			if (!gating_wait)
> +				udelay(1);
> +			else
> +				usleep_range(gating_wait, gating_wait + 10);
> +		}
>   
>   		writel_relaxed(temp, host->dev_ref_clk_ctrl_mmio);
>   


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