linux-kernel - RE: [PATCH 7/8] scsi: ufs: core: Toggle Write Booster during clock scaling base on gear speed

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-ID:
 <DM6PR04MB657571E3A0EFA0E0400FD0A4FC1A2@DM6PR04MB6575.namprd04.prod.outlook.com>
Date: Thu, 16 Jan 2025 13:27:35 +0000
From: Avri Altman <Avri.Altman@....com>
To: Ziqi Chen <quic_ziqichen@...cinc.com>, "quic_cang@...cinc.com"
	<quic_cang@...cinc.com>, "bvanassche@....org" <bvanassche@....org>,
	"mani@...nel.org" <mani@...nel.org>, "beanhuo@...ron.com"
	<beanhuo@...ron.com>, "junwoo80.lee@...sung.com" <junwoo80.lee@...sung.com>,
	"martin.petersen@...cle.com" <martin.petersen@...cle.com>,
	"quic_nguyenb@...cinc.com" <quic_nguyenb@...cinc.com>,
	"quic_nitirawa@...cinc.com" <quic_nitirawa@...cinc.com>,
	"quic_rampraka@...cinc.com" <quic_rampraka@...cinc.com>
CC: "linux-scsi@...r.kernel.org" <linux-scsi@...r.kernel.org>, Alim Akhtar
	<alim.akhtar@...sung.com>, "James E.J. Bottomley"
	<James.Bottomley@...senPartnership.com>, Peter Wang
	<peter.wang@...iatek.com>, Manivannan Sadhasivam
	<manivannan.sadhasivam@...aro.org>, Andrew Halaney <ahalaney@...hat.com>,
	Maramaina Naresh <quic_mnaresh@...cinc.com>, Eric Biggers
	<ebiggers@...gle.com>, Minwoo Im <minwoo.im@...sung.com>, open list
	<linux-kernel@...r.kernel.org>
Subject: RE: [PATCH 7/8] scsi: ufs: core: Toggle Write Booster during clock
 scaling base on gear speed

> 
> From: Can Guo <quic_cang@...cinc.com>
> 
> During clock scaling, Write Booster is toggled on or off based on whether the
> clock is scaled up or down. However, with OPP V2 powered multi-level gear
> scaling, the gear can be scaled amongst multiple gear speeds, e.g., it may
> scale down from G5 to G4, or from G4 to G2. To provide flexibilities, add a
> new field for clock scaling such that during clock scaling Write Booster can be
> enabled or disabled based on gear speeds but not based on scaling up or
> down.
> 
> Co-developed-by: Ziqi Chen <quic_ziqichen@...cinc.com>
> Signed-off-by: Ziqi Chen <quic_ziqichen@...cinc.com>
> Signed-off-by: Can Guo <quic_cang@...cinc.com>
> ---
>  drivers/ufs/core/ufshcd.c | 17 ++++++++++++-----
>  include/ufs/ufshcd.h      |  3 +++
>  2 files changed, 15 insertions(+), 5 deletions(-)
> 
> diff --git a/drivers/ufs/core/ufshcd.c b/drivers/ufs/core/ufshcd.c index
> 721bf9d1a356..31ebf267135b 100644
> --- a/drivers/ufs/core/ufshcd.c
> +++ b/drivers/ufs/core/ufshcd.c
> @@ -1395,13 +1395,17 @@ static int ufshcd_clock_scaling_prepare(struct
> ufs_hba *hba, u64 timeout_us)
>         return ret;
>  }
> 
> -static void ufshcd_clock_scaling_unprepare(struct ufs_hba *hba, int err, bool
> scale_up)
> +static void ufshcd_clock_scaling_unprepare(struct ufs_hba *hba, int
> +err)
>  {
>         up_write(&hba->clk_scaling_lock);
> 
> -       /* Enable Write Booster if we have scaled up else disable it */
> -       if (ufshcd_enable_wb_if_scaling_up(hba) && !err)
> -               ufshcd_wb_toggle(hba, scale_up);
> +       /* Enable Write Booster if current gear requires it else disable it */
> +       if (ufshcd_enable_wb_if_scaling_up(hba) && !err) {
> +               bool wb_en;
Can be initialized?

> +
> +               wb_en = hba->pwr_info.gear_rx >= hba->clk_scaling.wb_gear ? true
> : false;

If (wb != hba->dev_info.wb_enabled)
> +               ufshcd_wb_toggle(hba, wb_en);
> +       }
Wouldn't it make sense to move the wb toggling to ufshcd_scale_gear ?
This way you'll be able to leave the legacy on/off toggling?

> 
>         mutex_unlock(&hba->wb_mutex);
> 
> @@ -1456,7 +1460,7 @@ static int ufshcd_devfreq_scale(struct ufs_hba
> *hba, unsigned long freq,
>         }
> 
>  out_unprepare:
> -       ufshcd_clock_scaling_unprepare(hba, ret, scale_up);
> +       ufshcd_clock_scaling_unprepare(hba, ret);
>         return ret;
>  }
> 
> @@ -1816,6 +1820,9 @@ static void ufshcd_init_clk_scaling(struct ufs_hba
> *hba)
>         if (!hba->clk_scaling.min_gear)
>                 hba->clk_scaling.min_gear = UFS_HS_G1;
> 
> +       if (!hba->clk_scaling.wb_gear)
> +               hba->clk_scaling.wb_gear = UFS_HS_G3;
So you will toggle wb off on init (pwm) and on sporadic writes.
I guess there is no harm done.

Thanks,
Avri

> +
>         INIT_WORK(&hba->clk_scaling.suspend_work,
>                   ufshcd_clk_scaling_suspend_work);
>         INIT_WORK(&hba->clk_scaling.resume_work,
> diff --git a/include/ufs/ufshcd.h b/include/ufs/ufshcd.h index
> 8c7c497d63d3..8e6c2eb68011 100644
> --- a/include/ufs/ufshcd.h
> +++ b/include/ufs/ufshcd.h
> @@ -448,6 +448,8 @@ struct ufs_clk_gating {
>   * @resume_work: worker to resume devfreq
>   * @target_freq: frequency requested by devfreq framework
>   * @min_gear: lowest HS gear to scale down to
> + * @wb_gear: enable Write Booster when HS gear scales above or equal to
> it, else
> + *             disable Write Booster
>   * @is_enabled: tracks if scaling is currently enabled or not, controlled by
>   *             clkscale_enable sysfs node
>   * @is_allowed: tracks if scaling is currently allowed or not, used to block
> @@ -468,6 +470,7 @@ struct ufs_clk_scaling {
>         struct work_struct resume_work;
>         unsigned long target_freq;
>         u32 min_gear;
> +       u32 wb_gear;
>         bool is_enabled;
>         bool is_allowed;
>         bool is_initialized;
> --
> 2.34.1