linux-kernel - RE: [PATCH] ufs: core: Initialize a variable mode for PA

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Message-ID: <000001dc3c1a$33e23030$9ba69090$@samsung.com>
Date: Mon, 13 Oct 2025 17:20:14 +0900
From: "Wonkon Kim" <wkon.kim@...sung.com>
To: "'Bart Van Assche'" <bvanassche@....org>,
	<James.Bottomley@...senPartnership.com>, <martin.petersen@...cle.com>,
	<peter.wang@...iatek.com>, <linux-scsi@...r.kernel.org>,
	<linux-kernel@...r.kernel.org>
Subject: RE: [PATCH] ufs: core: Initialize a variable mode for PA_PWRMODE

> On 10/2/25 12:00 AM, Wonkon Kim wrote:
> >   static bool ufshcd_is_pwr_mode_restore_needed(struct ufs_hba *hba)
> >   {
> >   	struct ufs_pa_layer_attr *pwr_info = &hba->pwr_info;
> > -	u32 mode;
> > +	u32 mode = 0;
> >
> >   	ufshcd_dme_get(hba, UIC_ARG_MIB(PA_PWRMODE), &mode);
> 
> Since there is more code that passes a pointer to an uninitialized
> variable to ufshcd_dme_get(), the untested patch below may be a better
> solution:
> 
> diff --git a/drivers/ufs/core/ufshcd.c b/drivers/ufs/core/ufshcd.c index
> 127b691402f9..5226fbca29ec 100644
> --- a/drivers/ufs/core/ufshcd.c
> +++ b/drivers/ufs/core/ufshcd.c
> @@ -4277,8 +4277,8 @@ int ufshcd_dme_get_attr(struct ufs_hba *hba, u32
> attr_sel,
>   			get, UIC_GET_ATTR_ID(attr_sel),
>   			UFS_UIC_COMMAND_RETRIES - retries);
> 
> -	if (mib_val && !ret)
> -		*mib_val = uic_cmd.argument3;
> +	if (mib_val)
> +		*mib_val = ret == 0 ? uic_cmd.argument3 : 0;
> 
>   	if (peer && (hba->quirks & UFSHCD_QUIRK_DME_PEER_ACCESS_AUTO_MODE)
>   	    && pwr_mode_change)
> 
> 

There are some attributes to use 0 as valid value.
e.g. PA_MAXRXHSGEAR is set to 0 for NO_HS=0
If it has 0 for valid value, most of value 0 are regarded as FALSE, unsupported or minimum.
And these cases seems to check ret for command success/fail in code.
However, is it ok to set 0 for ufshcd_send_uic_cmd() fail?

If it can't, it needs to initialize mode.
Value 0 for PA_PWRMODE is invalid.


Thanks,
Wonkon Kim.