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Message-ID: <c1f2b758-85b6-40af-a2a3-e214e625fd9e@quicinc.com>
Date: Fri, 11 Oct 2024 17:42:23 +0530
From: Mukesh Kumar Savaliya <quic_msavaliy@...cinc.com>
To: Bjorn Andersson <quic_bjorande@...cinc.com>
CC: <konrad.dybcio@...aro.org>, <andersson@...nel.org>,
<andi.shyti@...nel.org>, <linux-arm-msm@...r.kernel.org>,
<linux-kernel@...r.kernel.org>, <linux-i2c@...r.kernel.org>,
<quic_vdadhani@...cinc.com>, Vinod Koul <vkoul@...nel.org>
Subject: Re: [PATCH v1] i2c: i2c-qcom-geni: Serve transfer during early resume
stage
Thanks Bjorn for the review.
On 4/5/2024 8:40 AM, Bjorn Andersson wrote:
> On Thu, Mar 28, 2024 at 06:07:43PM +0530, Mukesh Kumar Savaliya wrote:
>> 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 force
>> resume.
>>
>> 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.
>>
>> 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>
>> ---
>> drivers/i2c/busses/i2c-qcom-geni.c | 55 ++++++++++++++++++++++++------
>> 1 file changed, 45 insertions(+), 10 deletions(-)
>>
>> diff --git a/drivers/i2c/busses/i2c-qcom-geni.c b/drivers/i2c/busses/i2c-qcom-geni.c
>> index da94df466e83..ed8201983a03 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
>> @@ -677,22 +679,48 @@ 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);
>> + if (ret) {
>> + dev_err(gi2c->se.dev, "Error turning SE resources:%d\n", ret);
>
> "error turning"? How about "Failed to enable SE resources: %d\n"?
Sounds good, Thanks. Made this change.
>
>> + pm_runtime_put_noidle(dev);
>> + pm_runtime_set_suspended(dev);
>
> These two where the error-handling for pm_runtime_get_sync() failing, in
> one case below you get here after pm_runtime_get_sync() failed in the
> other you have not attempted to call that function.
>
Hi Bjorn, could you please clarify further on this question ? I am not
getting two instances for failure of pm_runtime_get_sync().
> Do you really get through this with things balanced?
We haven't seen imbalance in the usage count with added debug logs locally.
>
>> + return ret;
>> + }
>> + pm_runtime_get_noresume(dev);
>> + pm_runtime_set_active(dev);
>> + return ret;
>
> ret is 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;
>> +
>> + if (!pm_runtime_enabled(dev) && gi2c->suspended) {
>> + dev_dbg(gi2c->se.dev, "RT_PM disabled, Do force resume, usage_count:%d\n",
>
> "RT_PM" is not a widely used abbreviation for this...
Agree. Modified as "Runtime PM is disabled"
>
>> + 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(gi2c->se.dev, "PM get_sync() failed-%d, force resume\n", ret);
>
> Different abbreviation, different formatting of error value in log
> line...
yes, improved as ""pm_runtime_get_sync() failed"
>
>> + ret = geni_i2c_force_resume(gi2c);
>> + if (ret)
>> + return ret;
>
> This chunk looks identical to the chunk above, can this somehow be
> restructured to avoid the duplication?
I see different failure condition and then conditional call to
geni_i2c_force_resume(). Could you please highlight exact optimization ?
>
>> + }
>> }
>>
>> qcom_geni_i2c_conf(gi2c);
>> @@ -702,8 +730,15 @@ 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);
>
> I'm not sure I follow this part, please add a comment here for the
> future reader.
sure, Added comment in next patch.
>
>> + if (!pm_runtime_enabled(dev) && !gi2c->suspended) {
>> + pm_runtime_put_noidle(dev);
>> + pm_runtime_set_suspended(dev);
>> + gi2c->suspended = 0;
>
> Why alter suspended flag in xfer()?
>
Because force_resume() makes it active with respect to the
> Regards,
> Bjorn
>
>> + } else {
>> + pm_runtime_mark_last_busy(gi2c->se.dev);
>> + pm_runtime_put_autosuspend(gi2c->se.dev);
>> + }
>> +
>> gi2c->cur = NULL;
>> gi2c->err = 0;
>> return ret;
>> @@ -820,7 +855,7 @@ 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, 0,
>> + ret = devm_request_irq(dev, gi2c->irq, geni_i2c_irq, 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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