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SubjectRe: [PATCH v4 7/8] scsi: ufs-qcom: Delay specific time before gate ref clk
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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@codeaurora.org>
> ---

Reviewed-by: Asutosh Das <asutoshd@codeaurora.org>

> 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);
>
>


--
The Qualcomm Innovation Center, Inc. is a member of the Code Aurora Forum,
Linux Foundation Collaborative Project

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