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[83.9.29.190]) by smtp.gmail.com with ESMTPSA id s9-20020a19ad49000000b004f5bc4e80easm1497296lfd.171.2023.06.12.10.03.04 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Mon, 12 Jun 2023 10:03:05 -0700 (PDT) Message-ID: Date: Mon, 12 Jun 2023 19:03:04 +0200 MIME-Version: 1.0 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:102.0) Gecko/20100101 Thunderbird/102.11.2 Subject: Re: [PATCH v2 04/22] clk: qcom: smd-rpm: Export clock scaling availability Content-Language: en-US From: Konrad Dybcio To: Stephan Gerhold Cc: Andy Gross , Bjorn Andersson , Michael Turquette , Stephen Boyd , Georgi Djakov , Leo Yan , Evan Green , Marijn Suijten , linux-arm-msm@vger.kernel.org, linux-kernel@vger.kernel.org, linux-clk@vger.kernel.org, linux-pm@vger.kernel.org References: <20230526-topic-smd_icc-v2-0-e5934b07d813@linaro.org> <20230526-topic-smd_icc-v2-4-e5934b07d813@linaro.org> <40f937bb-0d7e-a237-1672-5905983622ce@linaro.org> In-Reply-To: Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit Precedence: bulk List-ID: X-Mailing-List: linux-pm@vger.kernel.org On 12.06.2023 14:51, Konrad Dybcio wrote: > On 11.06.2023 11:20, Stephan Gerhold wrote: >> On Sat, Jun 10, 2023 at 09:39:00PM +0200, Konrad Dybcio wrote: >>> On 10.06.2023 21:25, Stephan Gerhold wrote: >>>> On Sat, Jun 10, 2023 at 08:53:05PM +0200, Konrad Dybcio wrote: >>>>> On 10.06.2023 14:15, Konrad Dybcio wrote: >>>>>> On 10.06.2023 13:35, Stephan Gerhold wrote: >>>>>>> On Fri, Jun 09, 2023 at 10:19:09PM +0200, Konrad Dybcio wrote: >>>>>>>> Before we issue a call to RPM through clk_smd_rpm_enable_scaling() the >>>>>>>> clock rate requests will not be commited in hardware. This poses a >>>>>>>> race threat since we're accessing the bus clocks directly from within >>>>>>>> the interconnect framework. >>>>>>>> >>>>>>>> Add a marker to indicate that we're good to go with sending new requests >>>>>>>> and export it so that it can be referenced from icc. >>>>>>>> >>>>>>>> Signed-off-by: Konrad Dybcio >>>>>>>> --- >>>>>>>> drivers/clk/qcom/clk-smd-rpm.c | 9 +++++++++ >>>>>>>> include/linux/soc/qcom/smd-rpm.h | 2 ++ >>>>>>>> 2 files changed, 11 insertions(+) >>>>>>>> >>>>>>>> diff --git a/drivers/clk/qcom/clk-smd-rpm.c b/drivers/clk/qcom/clk-smd-rpm.c >>>>>>>> index 937cb1515968..482fe30ee6f0 100644 >>>>>>>> --- a/drivers/clk/qcom/clk-smd-rpm.c >>>>>>>> +++ b/drivers/clk/qcom/clk-smd-rpm.c >>>>>>>> @@ -151,6 +151,7 @@ >>>>>>>> #define to_clk_smd_rpm(_hw) container_of(_hw, struct clk_smd_rpm, hw) >>>>>>>> >>>>>>>> static struct qcom_smd_rpm *rpmcc_smd_rpm; >>>>>>>> +static bool smd_rpm_clk_scaling; >>>>>>>> >>>>>>>> struct clk_smd_rpm { >>>>>>>> const int rpm_res_type; >>>>>>>> @@ -385,6 +386,12 @@ static unsigned long clk_smd_rpm_recalc_rate(struct clk_hw *hw, >>>>>>>> return r->rate; >>>>>>>> } >>>>>>>> >>>>>>>> +bool qcom_smd_rpm_scaling_available(void) >>>>>>>> +{ >>>>>>>> + return smd_rpm_clk_scaling; >>>>>>>> +} >>>>>>>> +EXPORT_SYMBOL_GPL(qcom_smd_rpm_scaling_available); >>>>>>>> + >>>>>>>> static int clk_smd_rpm_enable_scaling(void) >>>>>>>> { >>>>>>>> int ret; >>>>>>>> @@ -410,6 +417,8 @@ static int clk_smd_rpm_enable_scaling(void) >>>>>>>> return ret; >>>>>>>> } >>>>>>>> >>>>>>>> + smd_rpm_clk_scaling = true; >>>>>>>> + >>>>>>> >>>>>>> If you move the platform_device_register_data(&rpdev->dev, >>>>>>> "icc_smd_rpm", ...) from drivers/soc/qcom/smd-rpm.c to here you can >>>>>>> avoid the race completely and drop this API. I think that would be >>>>>>> cleaner. And it will likely probe much faster because probe deferral >>>>>>> is slow. :) >>>>>> Sounds like an idea.. especially since it's pretty much the only >>>>>> dependency other than SMDRPM itself! >>>>> It sounds great, but to not break bisecting one has to: >>>>> >>>>> 1. change the registration in soc/smd-rpm to store rpm ptr in driver >>>>> data, in addition to parent driver data >>>>> >>>>> 2. change icc/smd-rpm to use the device and not parent data >>>>> >>>>> 3. add a platform_device_register_data call in clk-smd-rpm that will >>>>> always fail because the device is always registered >>>>> >>>>> 4. remove the registration from soc/smd-rpm >>>>> >>>> >>>> Logically the icc_smd_rpm device still fits better as child of >>>> smd-rpm and not clk-smd-rpm. So I would probably just continue >>>> registering it on the parent device from clk-smd-rpm. >>>> Then there are no changes necessary in icc_smd_rpm. >>>> >>>> You could use this. Both touched files are Bjorn-maintained so should be >>>> manageable to have it in one commit. (note: compile-tested only) >>>> >>>> Thanks, >>>> Stephan >>>> >>>> From a2610adb2551b01e76b9de8e4cbcc89853814a8f Mon Sep 17 00:00:00 2001 >>>> From: Stephan Gerhold >>>> Date: Sat, 10 Jun 2023 21:19:48 +0200 >>>> Subject: [PATCH] soc: qcom: smd-rpm: Move icc_smd_rpm registration to >>>> clk-smd-rpm >>>> >>>> icc_smd_rpm will do bus clock votes itself rather than taking the >>>> unnecessary detour through the clock subsystem. However, it can only >>>> do that after the clocks have been handed off and scaling has been >>>> enabled in the RPM in clk-smd-rpm. >>>> >>>> Move the icc_smd_rpm registration from smd-rpm.c to clk-smd-rpm.c >>>> to avoid any possible races. icc_smd_rpm gets the driver data from >>>> the smd-rpm device, so still register the platform device on the >>>> smd-rpm parent device. >>>> >>>> Signed-off-by: Stephan Gerhold >>>> --- >>> Generally it looks good.. I'll give it a spin next week. One >>> thing below. >>> >>>> drivers/clk/qcom/clk-smd-rpm.c | 21 +++++++++++++++++++++ >>>> drivers/soc/qcom/smd-rpm.c | 23 +---------------------- >>>> 2 files changed, 22 insertions(+), 22 deletions(-) >>>> >>>> diff --git a/drivers/clk/qcom/clk-smd-rpm.c b/drivers/clk/qcom/clk-smd-rpm.c >>>> index e4de74b68797..91adb16889b3 100644 >>>> --- a/drivers/clk/qcom/clk-smd-rpm.c >>>> +++ b/drivers/clk/qcom/clk-smd-rpm.c >>>> @@ -1302,12 +1302,20 @@ static struct clk_hw *qcom_smdrpm_clk_hw_get(struct of_phandle_args *clkspec, >>>> return desc->clks[idx] ? &desc->clks[idx]->hw : ERR_PTR(-ENOENT); >>>> } >>>> >>>> +static void rpm_smd_unregister_icc(void *data) >>>> +{ >>>> + struct platform_device *icc_pdev = data; >>>> + >>>> + platform_device_unregister(icc_pdev); >>>> +} >>>> + >>>> static int rpm_smd_clk_probe(struct platform_device *pdev) >>>> { >>>> int ret; >>>> size_t num_clks, i; >>>> struct clk_smd_rpm **rpm_smd_clks; >>>> const struct rpm_smd_clk_desc *desc; >>>> + struct platform_device *icc_pdev; >>>> >>>> rpmcc_smd_rpm = dev_get_drvdata(pdev->dev.parent); >>>> if (!rpmcc_smd_rpm) { >>>> @@ -1357,6 +1365,19 @@ static int rpm_smd_clk_probe(struct platform_device *pdev) >>>> if (ret) >>>> goto err; >>>> >>>> + icc_pdev = platform_device_register_data(pdev->dev.parent, >>>> + "icc_smd_rpm", -1, NULL, 0); >>>> + if (IS_ERR(icc_pdev)) { >>>> + dev_err(&pdev->dev, "Failed to register icc_smd_rpm device: %pE\n", >>>> + icc_pdev); >>>> + /* No need to unregister clocks because of this */ >>>> + } else { >>>> + ret = devm_add_action_or_reset(&pdev->dev, rpm_smd_unregister_icc, >>>> + icc_pdev); >>>> + if (ret) >>>> + goto err; >>>> + } >>>> + >>>> return 0; >>>> err: >>>> dev_err(&pdev->dev, "Error registering SMD clock driver (%d)\n", ret); >>>> diff --git a/drivers/soc/qcom/smd-rpm.c b/drivers/soc/qcom/smd-rpm.c >>>> index 0c1aa809cc4e..427dd5392b82 100644 >>>> --- a/drivers/soc/qcom/smd-rpm.c >>>> +++ b/drivers/soc/qcom/smd-rpm.c >>>> @@ -19,7 +19,6 @@ >>>> /** >>>> * struct qcom_smd_rpm - state of the rpm device driver >>>> * @rpm_channel: reference to the smd channel >>>> - * @icc: interconnect proxy device >>>> * @dev: rpm device >>>> * @ack: completion for acks >>>> * @lock: mutual exclusion around the send/complete pair >>>> @@ -27,7 +26,6 @@ >>>> */ >>>> struct qcom_smd_rpm { >>>> struct rpmsg_endpoint *rpm_channel; >>>> - struct platform_device *icc; >>>> struct device *dev; >>>> >>>> struct completion ack; >>>> @@ -197,7 +195,6 @@ static int qcom_smd_rpm_callback(struct rpmsg_device *rpdev, >>>> static int qcom_smd_rpm_probe(struct rpmsg_device *rpdev) >>>> { >>>> struct qcom_smd_rpm *rpm; >>>> - int ret; >>>> >>>> rpm = devm_kzalloc(&rpdev->dev, sizeof(*rpm), GFP_KERNEL); >>>> if (!rpm) >>>> @@ -210,24 +207,7 @@ static int qcom_smd_rpm_probe(struct rpmsg_device *rpdev) >>>> rpm->rpm_channel = rpdev->ept; >>>> dev_set_drvdata(&rpdev->dev, rpm); >>>> >>>> - rpm->icc = platform_device_register_data(&rpdev->dev, "icc_smd_rpm", -1, >>>> - NULL, 0); >>>> - if (IS_ERR(rpm->icc)) >>>> - return PTR_ERR(rpm->icc); >>>> - >>>> - ret = of_platform_populate(rpdev->dev.of_node, NULL, NULL, &rpdev->dev); >>>> - if (ret) >>>> - platform_device_unregister(rpm->icc); >>>> - >>>> - return ret; >>>> -} >>>> - >>>> -static void qcom_smd_rpm_remove(struct rpmsg_device *rpdev) >>>> -{ >>>> - struct qcom_smd_rpm *rpm = dev_get_drvdata(&rpdev->dev); >>>> - >>>> - platform_device_unregister(rpm->icc); >>>> - of_platform_depopulate(&rpdev->dev); >>>> + return devm_of_platform_populate(&rpdev->dev); >>>> } >>>> >>>> static const struct of_device_id qcom_smd_rpm_of_match[] = { >>>> @@ -256,7 +236,6 @@ MODULE_DEVICE_TABLE(of, qcom_smd_rpm_of_match); >>>> >>>> static struct rpmsg_driver qcom_smd_rpm_driver = { >>>> .probe = qcom_smd_rpm_probe, >>>> - .remove = qcom_smd_rpm_remove, >>> This reaches over the removal of the icc registration, the depopulate >>> call should stay. >>> >> >> I switched the of_platform_populate() to devm_of_platform_populate(), >> that's why the remove callback is no longer necessary. It's a bit >> hidden, perhaps it would be enough to add to the commit message: >> >> "While at it, switch the remaining of_platform_populate() call to the >> devm variant and remove the remove callback." >> >> Or maybe it should be split into two patches. > Gave it a spin, I think it ends up being worse if an IPA rpm clock is > consumed by one of the icc providers, and that's sadly the case > for almost all platforms (or supposed to be).. :/ Only qcm2290 doesn't > seem to care if we poke the network interface units with half the soc > off :P Actually it's more complex and that rings the same tons-of-probe-deferrals bell that we have to get rid of.. The icc_smd_rpm driver actually does probe faster with your patch, but that's not the case with the SoC icc provider driver which does probe later :/ Don't think either solution is perfect, but I'm willing to take your solution, as the one I proposed is a bit of a dead end for future improvements. Konrad > > Konrad >> >> Thanks, >> Stephan