Re: [PATCH v5 5/8] scsi: ufs: core: Enable multi-level gear scaling

[Neil Armstrong]

Hi,

On 13/02/2025 09:00, 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 appropriate gear speeds accordingly.
>
> Signed-off-by: Can Guo <quic_cang@xxxxxxxxxxx>
> Co-developed-by: Ziqi Chen <quic_ziqichen@xxxxxxxxxxx>
> Signed-off-by: Ziqi Chen <quic_ziqichen@xxxxxxxxxxx>
> Reviewed-by: Bean Huo <beanhuo@xxxxxxxxxx>
> Reviewed-by: Bart Van Assche <bvanassche@xxxxxxx>
> Tested-by: Neil Armstrong <neil.armstrong@xxxxxxxxxx>
> ---
>
> v1 -> v2:
> Rename the lable "do_pmc" to "config_pwr_mode".
>
> v2 -> v3:
> Use assignment instead memcpy() in function ufshcd_scale_gear().
>
> v3 -> v4:
> Typo fixed for commit message.
>
> v4 -> v5:
> Change the data type of "new_gear" from 'int' to 'u32'.
> ---
>   drivers/ufs/core/ufshcd.c | 44 ++++++++++++++++++++++++++++++---------
>   1 file changed, 34 insertions(+), 10 deletions(-)
>
> diff --git a/drivers/ufs/core/ufshcd.c b/drivers/ufs/core/ufshcd.c
> index 8d295cc827cc..9908c0d6a1e1 100644
> --- a/drivers/ufs/core/ufshcd.c
> +++ b/drivers/ufs/core/ufshcd.c
> @@ -1308,16 +1308,26 @@ 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) {
> +		new_pwr_info = hba->pwr_info;
> +		new_pwr_info.gear_tx = target_gear;
> +		new_pwr_info.gear_rx = target_gear;
> +
> +		goto config_pwr_mode;
> +	}
> +
> +	/* 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 +1348,7 @@ static int ufshcd_scale_gear(struct ufs_hba *hba, bool scale_up)
>   		}
>   	}
>   
> +config_pwr_mode:
>   	/* check if the power mode needs to be changed or not? */
>   	ret = ufshcd_config_pwr_mode(hba, &new_pwr_info);
>   	if (ret)
> @@ -1408,15 +1419,19 @@ 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;
>   
> +	new_gear = ufshcd_vops_freq_to_gear_speed(hba, freq);
> +
>   	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 +1439,13 @@ 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 +1738,8 @@ 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 +1763,21 @@ 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;
> +
> +out_rel:
>   	ufshcd_release(hba);
>   	ufshcd_rpm_put_sync(hba);
>   out:

This change causes UFS crash on the RB3gen2, after UFS successfully probe and scan:

[    9.383728] ufshcd-qcom 1d84000.ufshc: pwr ctrl cmd 0x2 with mode 0x11 completion timeout
[    9.393272] ufshcd-qcom 1d84000.ufshc: UFS Host state=1
[    9.403126] msm_dpu ae01000.display-controller: [drm:adreno_request_fw [msm]] *ERROR* failed to load a660_sqe.fw
[    9.408484] ufshcd-qcom 1d84000.ufshc: 0 outstanding reqs, tasks=0x0
[    9.425577] ufshcd-qcom 1d84000.ufshc: saved_err=0x0, saved_uic_err=0x0
[    9.432433] ufshcd-qcom 1d84000.ufshc: Device power mode=1, UIC link state=1
[    9.439716] ufshcd-qcom 1d84000.ufshc: PM in progress=0, sys. suspended=0
[    9.446742] ufshcd-qcom 1d84000.ufshc: Auto BKOPS=0, Host self-block=0
[    9.453468] ufshcd-qcom 1d84000.ufshc: Clk gate=1
...
[   10.529259] ufshcd-qcom 1d84000.ufshc: ufshcd_change_power_mode: power mode change failed -110
[   10.538102] ufshcd-qcom 1d84000.ufshc: ufshcd_scale_gear: failed err -110, old gear: (tx 1 rx 1), new gear: (tx 4 rx 4)
[   10.542841] WARNING: CPU: 0 PID: 274 at drivers/ufs/core/ufshcd.c:5504 ufshcd_sl_intr+0x64c/0x6a4
...

CI Run sample: https://git.codelinaro.org/linaro/qcomlt/ci/staging/cdba-tester/-/jobs/233352#L1479

Bisect run log:
# bad: [0af2f6be1b4281385b618cb86ad946eded089ac8] Linux 6.15-rc1
# good: [38fec10eb60d687e30c8c6b5420d86e8149f7557] Linux 6.14
git bisect start 'v6.15-rc1' 'v6.14'
# bad: [fd71def6d9abc5ae362fb9995d46049b7b0ed391] Merge tag 'for-6.15-tag' of git://git.kernel.org/pub/scm/linux/kernel/git/kdave/linux
git bisect bad fd71def6d9abc5ae362fb9995d46049b7b0ed391
# good: [fb1ceb29b27cda91af35851ebab01f298d82162e] Merge tag 'platform-drivers-x86-v6.15-1' of git://git.kernel.org/pub/scm/linux/kernel/git/pdx86/platform-drivers-x86
git bisect good fb1ceb29b27cda91af35851ebab01f298d82162e
# good: [1952e19c02ae8ea0c663d30b19be14344b543068] Merge tag 'wireless-next-2025-03-20' of https://git.kernel.org/pub/scm/linux/kernel/git/wireless/wireless-next
git bisect good 1952e19c02ae8ea0c663d30b19be14344b543068
# bad: [1a9239bb4253f9076b5b4b2a1a4e8d7defd77a95] Merge tag 'net-next-6.15' of git://git.kernel.org/pub/scm/linux/kernel/git/netdev/net-next
git bisect bad 1a9239bb4253f9076b5b4b2a1a4e8d7defd77a95
# good: [22093997ac9220d3c606313efbf4ce564962d095] Merge tag 'ata-6.15-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/libata/linux
git bisect good 22093997ac9220d3c606313efbf4ce564962d095
# bad: [336b4dae6dfecc9aa53a3a68c71b9c1c1d466388] Merge tag 'iommu-updates-v6.15' of git://git.kernel.org/pub/scm/linux/kernel/git/iommu/linux
git bisect bad 336b4dae6dfecc9aa53a3a68c71b9c1c1d466388
# bad: [0711f1966a523d77d4c5f00776a7bd073d56251a] scsi: mpt3sas: Fix buffer overflow in mpt3sas_send_mctp_passthru_req()
git bisect bad 0711f1966a523d77d4c5f00776a7bd073d56251a
# good: [369552fd03f296261023872b8fc983d1fc55c8e9] Merge patch series "mpt3sas driver udpates"
git bisect good 369552fd03f296261023872b8fc983d1fc55c8e9
# bad: [42273e893157501ae119ea5459f3a7d2420c56d6] Merge patch series "scsi: scsi_debug: Add more tape support"
git bisect bad 42273e893157501ae119ea5459f3a7d2420c56d6
# bad: [7e72900272b61c11f2fd4020d4f186124d0d171b] Merge patch series "Support Multi-frequency scale for UFS"
git bisect bad 7e72900272b61c11f2fd4020d4f186124d0d171b
# good: [c02fe9e222d16bed8c270608c42f77bc62562ac3] scsi: ufs: qcom: Implement the freq_to_gear_speed() vop
git bisect good c02fe9e222d16bed8c270608c42f77bc62562ac3
# bad: [eff26ad4c34fc78303c14be749e10ca61c4d211f] scsi: ufs: core: Check if scaling up is required when disable clkscale
git bisect bad eff26ad4c34fc78303c14be749e10ca61c4d211f
# bad: [129b44c27c8a51cb74b2f68fde57f2a2e7f5696b] scsi: ufs: core: Enable multi-level gear scaling
git bisect bad 129b44c27c8a51cb74b2f68fde57f2a2e7f5696b
# first bad commit: [129b44c27c8a51cb74b2f68fde57f2a2e7f5696b] scsi: ufs: core: Enable multi-level gear scaling

#regzbot introduced 129b44c27c8a51cb74b2f68fde57f2a2e7f5696b

Thanks,
Neil