Messages in this thread | | | Date | Thu, 6 Feb 2020 12:33:36 -0800 | From | Bjorn Andersson <> | Subject | Re: [PATCH v7 7/8] scsi: ufs-qcom: Delay specific time before gate ref clk |
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On Thu 06 Feb 00:33 PST 2020, 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> > Reviewed-by: Hongwu Su <hongwus@codeaurora.org> > --- > drivers/scsi/ufs/ufs-qcom.c | 22 +++++++++++++++++++--- > 1 file changed, 19 insertions(+), 3 deletions(-) > > diff --git a/drivers/scsi/ufs/ufs-qcom.c b/drivers/scsi/ufs/ufs-qcom.c > index 85d7c17..39eefa4 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 +847,25 @@ 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) {
Afaict this can't happen, because in patch 6 you check for gating_wait being 0 and if so set it to 0xff.
> + udelay(1); > + } else { > + /* > + * bRefClkGatingWaitTime defines the minimum > + * time for which the reference clock is > + * required by device during transition from > + * HS-MODE to LS-MODE or HIBERN8 state. Give it > + * more time to be on the safe side. > + */ > + gating_wait += 10; > + usleep_range(gating_wait, gating_wait + 10);
I presume there's no strong requirement on the max, so how about using a substantially larger max - say 1k, or 10k - to allow the usleep_range() to do it's job?
PS. Please include linux-arm-msm@ on all the patches in the series, not just two of them.
Regards, Bjorn
> + } > + } > > writel_relaxed(temp, host->dev_ref_clk_ctrl_mmio); > > -- > The Qualcomm Innovation Center, Inc. is a member of the Code Aurora Forum, > a Linux Foundation Collaborative Project
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