From: Manu Gautam <mgautam@codeaurora.org>
To: Stephen Boyd <sboyd@kernel.org>,
Marc Gonzalez <marc.w.gonzalez@free.fr>,
Michael Turquette <mturquette@baylibre.com>
Cc: Jeffrey Hugo <jhugo@codeaurora.org>,
Bjorn Andersson <bjorn.andersson@linaro.org>,
linux-clk <linux-clk@vger.kernel.org>,
MSM <linux-arm-msm@vger.kernel.org>,
Evan Green <evgreen@chromium.org>,
Douglas Anderson <dianders@chromium.org>,
Vinod Koul <vkoul@kernel.org>,
Amit Nischal <anischal@codeaurora.org>
Subject: Re: [PATCH v1] clk: qcom: Skip halt checks on gcc_pcie_0_pipe_clk for 8998
Date: Thu, 10 Oct 2019 13:03:32 +0530 [thread overview]
Message-ID: <a8540fe3-9500-4998-ca25-a06269541383@codeaurora.org> (raw)
In-Reply-To: <20191010041551.6D7E0208C3@mail.kernel.org>
Hi,
On 10/10/2019 9:45 AM, Stephen Boyd wrote:
> Quoting Manu Gautam (2019-10-09 01:31:09)
>>
[snip]
>> I have followed this up with QMP PHY hardware designers and they have
>> confirmed that QMP PHY must have pipe clock enabled at the beginning
>> of initialization sequence i.e. before bringing it out of reset and starting it.
> Awesome, thanks for following up.
>
>> Otherwise there is possibility of incorrect locking of pipe_interface/
>> retime buffers in PHY.
>> Hence, for both USB and PCIe we have to continue to use HALT_SKIP flag.
> Does anything go wrong if we just leave these clks enabled forever out
> of boot? I'm inclined to rip the clks out and just slam the branch
> enable bit on all the time in gcc driver probe and return NULL to the
> callers of clk_get() for these clks. I don't see how this would be a
> problem because when the upstream phy is disabled this clk is disabled
> and so we aren't wasting power. It should also save us time and memory
> because now we don't have to call into the clk framework to turn it on
> and sequence that just right in the phy driver.
That might work, however on some platforms gcc_pipe_clk parent is changed to
XO and back to phy_pipe_clk across low power mode.
It requires PHY driver to use clk_set_parent().
--
The Qualcomm Innovation Center, Inc. is a member of the Code Aurora Forum,
a Linux Foundation Collaborative Project
next prev parent reply other threads:[~2019-10-10 7:39 UTC|newest]
Thread overview: 13+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-03-25 13:49 [PATCH v1] clk: qcom: Skip halt checks on gcc_pcie_0_pipe_clk for 8998 Marc Gonzalez
2019-03-28 16:26 ` Marc Gonzalez
2019-03-29 22:32 ` Stephen Boyd
2019-04-01 8:48 ` Marc Gonzalez
2019-10-09 8:31 ` Manu Gautam
2019-10-10 4:15 ` Stephen Boyd
2019-10-10 7:33 ` Manu Gautam [this message]
2019-10-10 19:48 ` Stephen Boyd
2019-10-11 3:47 ` Manu Gautam
2019-10-17 17:49 ` Stephen Boyd
2019-04-05 12:29 ` Marc Gonzalez
2019-04-09 13:25 ` Jeffrey Hugo
2019-04-11 20:38 ` Stephen Boyd
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