Re: [PATCH 5/8] scsi: ufs: core: Enable multi-level gear scaling

[Ziqi Chen <quic_ziqichen@xxxxxxxxxxx>]

Hi Mani,

Thanks for your comment~

On 1/19/2025 3:48 PM, Manivannan Sadhasivam wrote:
> On Thu, Jan 16, 2025 at 05:11:46PM +0800, Ziqi Chen wrote:
> > From: Can Guo <quic_cang@xxxxxxxxxxx>
> >
> > With OPP V2 enabled, devfreq can scale clocks amongst multiple frequency
> > plans. However, the gear speed is only toggled between min and max during
> > clock scaling. Enable multi-level gear scaling by mapping clock frequencies
> > to gear speeds, so that when devfreq scales clock frequencies we can put
> > the UFS link at the appropraite gear speeds accordingly.
> >
> > Co-developed-by: Ziqi Chen <quic_ziqichen@xxxxxxxxxxx>
> > Signed-off-by: Ziqi Chen <quic_ziqichen@xxxxxxxxxxx>
> > Signed-off-by: Can Guo <quic_cang@xxxxxxxxxxx>
> > ---
> >   drivers/ufs/core/ufshcd.c | 46 ++++++++++++++++++++++++++++++---------
> >   1 file changed, 36 insertions(+), 10 deletions(-)
> >
> > diff --git a/drivers/ufs/core/ufshcd.c b/drivers/ufs/core/ufshcd.c
> > index 8d295cc827cc..839bc23aeda0 100644
> > --- a/drivers/ufs/core/ufshcd.c
> > +++ b/drivers/ufs/core/ufshcd.c
> > @@ -1308,16 +1308,28 @@ static int ufshcd_wait_for_doorbell_clr(struct ufs_hba *hba,
> >   /**
> >    * ufshcd_scale_gear - scale up/down UFS gear
> >    * @hba: per adapter instance
> > + * @target_gear: target gear to scale to
> >    * @scale_up: True for scaling up gear and false for scaling down
> >    *
> >    * Return: 0 for success; -EBUSY if scaling can't happen at this time;
> >    * non-zero for any other errors.
> >    */
> > -static int ufshcd_scale_gear(struct ufs_hba *hba, bool scale_up)
> > +static int ufshcd_scale_gear(struct ufs_hba *hba, u32 target_gear, bool scale_up)
> >   {
> >   	int ret = 0;
> >   	struct ufs_pa_layer_attr new_pwr_info;
> >   
> > +	if (target_gear) {
> > +		memcpy(&new_pwr_info, &hba->pwr_info,
> > +		       sizeof(struct ufs_pa_layer_attr));
> > +
> > +		new_pwr_info.gear_tx = target_gear;
> > +		new_pwr_info.gear_rx = target_gear;
> > +
> > +		goto do_pmc;
>
> goto config_pwr_mode;

Ok, Thanks for your suggestion, I will change it in next version.

> > +	}
> > +
> > +	/* Legacy gear scaling, in case vops_freq_to_gear_speed() is not implemented */
> >   	if (scale_up) {
> >   		memcpy(&new_pwr_info, &hba->clk_scaling.saved_pwr_info,
> >   		       sizeof(struct ufs_pa_layer_attr));
> > @@ -1338,6 +1350,7 @@ static int ufshcd_scale_gear(struct ufs_hba *hba, bool scale_up)
> >   		}
> >   	}
> >   
> > +do_pmc:
> >   	/* check if the power mode needs to be changed or not? */
> >   	ret = ufshcd_config_pwr_mode(hba, &new_pwr_info);
> >   	if (ret)
> > @@ -1408,15 +1421,19 @@ static void ufshcd_clock_scaling_unprepare(struct ufs_hba *hba, int err, bool sc
> >   static int ufshcd_devfreq_scale(struct ufs_hba *hba, unsigned long freq,
> >   				bool scale_up)
> >   {
> > +	u32 old_gear = hba->pwr_info.gear_rx;
> > +	u32 new_gear = 0;
> >   	int ret = 0;
> >   
> > +	ufshcd_vops_freq_to_gear_speed(hba, freq, &new_gear);
> > +
> >   	ret = ufshcd_clock_scaling_prepare(hba, 1 * USEC_PER_SEC);
> >   	if (ret)
> >   		return ret;
> >   
> >   	/* scale down the gear before scaling down clocks */
> >   	if (!scale_up) {
> > -		ret = ufshcd_scale_gear(hba, false);
> > +		ret = ufshcd_scale_gear(hba, new_gear, false);
> >   		if (ret)
> >   			goto out_unprepare;
> >   	}
> > @@ -1424,13 +1441,13 @@ static int ufshcd_devfreq_scale(struct ufs_hba *hba, unsigned long freq,
> >   	ret = ufshcd_scale_clks(hba, freq, scale_up);
> >   	if (ret) {
> >   		if (!scale_up)
> > -			ufshcd_scale_gear(hba, true);
> > +			ufshcd_scale_gear(hba, old_gear, true);
> >   		goto out_unprepare;
> >   	}
> >   
> >   	/* scale up the gear after scaling up clocks */
> >   	if (scale_up) {
> > -		ret = ufshcd_scale_gear(hba, true);
> > +		ret = ufshcd_scale_gear(hba, new_gear, true);
> >   		if (ret) {
> >   			ufshcd_scale_clks(hba, hba->devfreq->previous_freq,
> >   					  false);
> > @@ -1723,6 +1740,8 @@ static ssize_t ufshcd_clkscale_enable_store(struct device *dev,
> >   		struct device_attribute *attr, const char *buf, size_t count)
> >   {
> >   	struct ufs_hba *hba = dev_get_drvdata(dev);
> > +	struct ufs_clk_info *clki;
> > +	unsigned long freq;
> >   	u32 value;
> >   	int err = 0;
> >   
> > @@ -1746,14 +1765,21 @@ static ssize_t ufshcd_clkscale_enable_store(struct device *dev,
> >   
> >   	if (value) {
> >   		ufshcd_resume_clkscaling(hba);
> > -	} else {
> > -		ufshcd_suspend_clkscaling(hba);
> > -		err = ufshcd_devfreq_scale(hba, ULONG_MAX, true);
> > -		if (err)
> > -			dev_err(hba->dev, "%s: failed to scale clocks up %d\n",
> > -					__func__, err);
> > +		goto out_rel;
> >   	}
> >   
> > +	clki = list_first_entry(&hba->clk_list_head, struct ufs_clk_info, list);
> > +	freq = clki->max_freq;
> > +
> > +	ufshcd_suspend_clkscaling(hba);
> > +	err = ufshcd_devfreq_scale(hba, freq, true);
> > +	if (err)
> > +		dev_err(hba->dev, "%s: failed to scale clocks up %d\n",
> > +				__func__, err);
> > +	else
> > +		hba->clk_scaling.target_freq = freq;
> > +
>
> Just noticed that the 'clkscale_enable', 'clkgate_{delay_ms}/enable' sysfs
> attributes have no ABI documentation. Please add them also in a separate patch.

Ok, I will update it in next version.

>  > - Mani

-Ziqi