linux-kernel - RE: [PATCH v1] scsi: ufs: remove clk_scaling

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Date:   Sat, 12 Feb 2022 13:44:34 +0900
From:   "Kiwoong Kim" <kwmad.kim@...sung.com>
To:     "'Adrian Hunter'" <adrian.hunter@...el.com>,
        "'Avri Altman'" <Avri.Altman@....com>,
        <linux-scsi@...r.kernel.org>, <linux-kernel@...r.kernel.org>,
        <alim.akhtar@...sung.com>, <jejb@...ux.ibm.com>,
        <martin.petersen@...cle.com>, <beanhuo@...ron.com>,
        <cang@...eaurora.org>, <sc.suh@...sung.com>,
        <hy50.seo@...sung.com>, <sh425.lee@...sung.com>,
        <bhoon95.kim@...sung.com>, <vkumar.1997@...sung.com>
Subject: RE: [PATCH v1] scsi: ufs: remove clk_scaling_lock when clkscaling
 isn't supported.

> The error handler really should have exclusive access.  One of the places
> you change does explain that:
> 
>  		 * Hold the scaling lock just in case dev cmds
>  		 * are sent via bsg and/or sysfs.
>  		 */
> -		down_write(&hba->clk_scaling_lock);
> +		if (ufshcd_is_clkscaling_supported(hba))
> +			down_write(&hba->clk_scaling_lock); 


Yeah.., I saw the comment but didn't get why.

Is there anyone who knows why it's necessary for all SoCs?
At lease, I know there is no reason to forbid concurrent executions of dev cmd and power mode change.

If there's nothing, how about adding a quick to ignore it?

Thanks.
Kiwoong Kim