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Message-ID: <3797c11f-b263-4f5d-9307-963fd6662b26@quicinc.com>
Date: Tue, 19 Nov 2024 19:59:44 +0530
From: Mukesh Kumar Savaliya <quic_msavaliy@...cinc.com>
To: Bjorn Andersson <bjorn.andersson@....qualcomm.com>
CC: <andi.shyti@...nel.org>, <quic_bjorande@...cinc.com>,
<linux-arm-msm@...r.kernel.org>, <linux-i2c@...r.kernel.org>,
<linux-kernel@...r.kernel.org>, <konrad.dybcio@...aro.org>,
<quic_vdadhani@...cinc.com>, <vkoul@...nel.org>
Subject: Re: [PATCH v2] i2c: i2c-qcom-geni: Serve transfer during early resume
stage
Hi Bjorn, thanks for the review.
On 10/11/2024 11:28 PM, Bjorn Andersson wrote:
> On Fri, Oct 11, 2024 at 05:47:57PM +0530, Mukesh Kumar Savaliya wrote:
>
> Your recipients list is broken. Please check go/upstream and adopt b4 to
> help avoid such mistakes.
>
Sorry, My mistake in keeping output of maintainers script separately
into --to and --cc which i shouldn't do.
>> pm_runtime_get_sync() function fails during PM early resume and returning
>> -EACCES because runtime PM for the device is disabled at the early stage
>> causing i2c transfer to fail. Make changes to serve transfer with forced
>> resume.
>>
>> Few i2c clients like PCI OR touch may request i2c transfers during early
>> resume stage. In order to serve transfer request do :
>>
>
> This problem description is too generic. I am not aware of any use case
> upstream where PCI or touch might need to perform i2c transfers during
> early resume; your commit message should educate me.
>
yes, it's generic as of now since we have an internal usecase with PCI
is yet to be enabled in upstream. Not tied up with any usecase in
upstream, i just heard recently.
Provided the scenario is generic and possible by any client, can this
code change be reviewed or shall be kept on halt till PCI usecase gets
enabled ?
>> 1. Register interrupt with IRQF_EARLY_RESUME and IRQF_NO_SUSPEND flags
>> to avoid timeout of transfer when IRQ is not enabled during early stage.
>> 2. Do force resume if pm_runtime_get_sync() is failing after system
>> suspend when runtime PM is not enabled.
>> 3. Increment power usage count after forced resume to balance
>> it against regular runtime suspend.
>>
>
> Please avoid the bullet list form technical description of your patch.
>
Sure. Made the changes in commit log with free flow writeup.
>> Co-developed-by: Viken Dadhaniya <quic_vdadhani@...cinc.com>
>> Signed-off-by: Viken Dadhaniya <quic_vdadhani@...cinc.com>
>> Signed-off-by: Mukesh Kumar Savaliya <quic_msavaliy@...cinc.com>
>> ---
>> v1 -> v2:
>>
>> - Changed gi2c->se.dev to dev during dev_dbg() calls.
>> - Addressed review comments from Andi and Bjorn.
>
> That's nice, but spell out the changes you're doing so that reviewers
> now what you did.
Sure, changes done are also listed but i will add reviewers name per change.
>
>> - Returned 0 instead garbage inside geni_i2c_force_resume().
>> - Added comments explaining forced resume transfer when runtime PM
>> remains disabled.
>>
>> V1 link: https://patches.linaro.org/project/linux-i2c/patch/20240328123743.1713696-1-quic_msavaliy@quicinc.com/
>> ---
>> ---
>> drivers/i2c/busses/i2c-qcom-geni.c | 61 +++++++++++++++++++++++++-----
>> 1 file changed, 51 insertions(+), 10 deletions(-)
>>
>> diff --git a/drivers/i2c/busses/i2c-qcom-geni.c b/drivers/i2c/busses/i2c-qcom-geni.c
>> index 212336f724a6..e1207f1a3de3 100644
>> --- a/drivers/i2c/busses/i2c-qcom-geni.c
>> +++ b/drivers/i2c/busses/i2c-qcom-geni.c
>> @@ -134,6 +134,8 @@ struct geni_i2c_clk_fld {
>> u8 t_cycle_cnt;
>> };
>>
>> +static int geni_i2c_runtime_resume(struct device *dev);
>> +
>> /*
>> * Hardware uses the underlying formula to calculate time periods of
>> * SCL clock cycle. Firmware uses some additional cycles excluded from the
>> @@ -675,22 +677,49 @@ static int geni_i2c_fifo_xfer(struct geni_i2c_dev *gi2c,
>> return num;
>> }
>>
>> +static int geni_i2c_force_resume(struct geni_i2c_dev *gi2c)
>> +{
>> + struct device *dev = gi2c->se.dev;
>> + int ret;
>> +
>> + ret = geni_i2c_runtime_resume(dev);
>
> Wouldn't pm_runtime_force_resume() help you do what you're looking for?
>
Yes, i have reviewed and seems this API can also serve the same purpose.
Made the changes accordingly.
>> + if (ret) {
>> + dev_err(gi2c->se.dev, "Failed to enable SE resources: %d\n", ret);
>> + pm_runtime_put_noidle(dev);
>> + pm_runtime_set_suspended(dev);
>> + return ret;
>> + }
>> + pm_runtime_get_noresume(dev);
>> + pm_runtime_set_active(dev);
>> + return 0;
>> +}
>> +
>> static int geni_i2c_xfer(struct i2c_adapter *adap,
>> struct i2c_msg msgs[],
>> int num)
>> {
>> struct geni_i2c_dev *gi2c = i2c_get_adapdata(adap);
>> + struct device *dev = gi2c->se.dev;
>> int ret;
>>
>> gi2c->err = 0;
>> reinit_completion(&gi2c->done);
>> - ret = pm_runtime_get_sync(gi2c->se.dev);
>> - if (ret < 0) {
>> - dev_err(gi2c->se.dev, "error turning SE resources:%d\n", ret);
>> - pm_runtime_put_noidle(gi2c->se.dev);
>> - /* Set device in suspended since resume failed */
>> - pm_runtime_set_suspended(gi2c->se.dev);
>> - return ret;
>> +
>> + /* Serve I2C transfer by forced resume whether Runtime PM is enbled or not */
>> + if (!pm_runtime_enabled(dev) && gi2c->suspended) {
>> + dev_dbg(dev, "Runtime PM is disabled hence force resume, pm_usage_count: %d\n",
>> + atomic_read(&dev->power.usage_count));
>> + ret = geni_i2c_force_resume(gi2c);
>> + if (ret)
>> + return ret;
>> + } else {
>> + ret = pm_runtime_get_sync(dev);
>> + if (ret == -EACCES && gi2c->suspended) {
>> + dev_dbg(dev, "pm_runtime_get_sync() failed-%d, force resume\n", ret);
>> + ret = geni_i2c_force_resume(gi2c);
>> + if (ret)
>> + return ret;
>> + }
>> }
>>
>> qcom_geni_i2c_conf(gi2c);
>> @@ -700,8 +729,19 @@ static int geni_i2c_xfer(struct i2c_adapter *adap,
>> else
>> ret = geni_i2c_fifo_xfer(gi2c, msgs, num);
>>
>> - pm_runtime_mark_last_busy(gi2c->se.dev);
>> - pm_runtime_put_autosuspend(gi2c->se.dev);
>> + /* Does Opposite to Forced Resume when runtime PM was not enabled and served
>> + * Transfer via forced resume.
>
> Please polish this comment.
Sure, Enhanced my comments. Thanks.
>
> Regards,
> Bjorn
>
>> + */
>> + if (!pm_runtime_enabled(dev) && !gi2c->suspended) {
>> + pm_runtime_put_noidle(dev);
>> + pm_runtime_set_suspended(dev);
>> + /* Reset flag same as runtime suspend, next xfer PM can be enabled */
>> + gi2c->suspended = 0;
>> + } else {
>> + pm_runtime_mark_last_busy(gi2c->se.dev);
>> + pm_runtime_put_autosuspend(gi2c->se.dev);
>> + }
>> +
>> gi2c->cur = NULL;
>> gi2c->err = 0;
>> return ret;
>> @@ -818,7 +858,8 @@ static int geni_i2c_probe(struct platform_device *pdev)
>> init_completion(&gi2c->done);
>> spin_lock_init(&gi2c->lock);
>> platform_set_drvdata(pdev, gi2c);
>> - ret = devm_request_irq(dev, gi2c->irq, geni_i2c_irq, IRQF_NO_AUTOEN,
>> + ret = devm_request_irq(dev, gi2c->irq, geni_i2c_irq,
>> + IRQF_NO_AUTOEN | IRQF_EARLY_RESUME | IRQF_NO_SUSPEND,
>> dev_name(dev), gi2c);
>> if (ret) {
>> dev_err(dev, "Request_irq failed:%d: err:%d\n",
>> --
>> 2.25.1
>>
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