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Message-ID: <ZwlnWIWkS1pwQ/xK@hu-bjorande-lv.qualcomm.com>
Date: Fri, 11 Oct 2024 10:58:48 -0700
From: Bjorn Andersson <bjorn.andersson@....qualcomm.com>
To: Mukesh Kumar Savaliya <quic_msavaliy@...cinc.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
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.
> 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.
> 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.
> 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.
> - 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?
> + 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.
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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