linux-kernel - RE: [PATCH] scsi: ufs: no sw reset after last linkstartup fail

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Date:   Tue, 5 Jul 2022 06:51:10 +0000
From:   Avri Altman <Avri.Altman@....com>
To:     Seunghui Lee <sh043.lee@...sung.com>,
        "alim.akhtar@...sung.com" <alim.akhtar@...sung.com>,
        "bvanassche@....org" <bvanassche@....org>,
        "jejb@...ux.ibm.com" <jejb@...ux.ibm.com>,
        "martin.petersen@...cle.com" <martin.petersen@...cle.com>,
        "linux-scsi@...r.kernel.org" <linux-scsi@...r.kernel.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>
CC:     "grant.jung@...sung.com" <grant.jung@...sung.com>,
        "jt77.jang@...sung.com" <jt77.jang@...sung.com>,
        "dh0421.hwang@...sung.com" <dh0421.hwang@...sung.com>,
        "junwoo80.lee@...sung.com" <junwoo80.lee@...sung.com>,
        "jangsub.yi@...sung.com" <jangsub.yi@...sung.com>,
        "cw9316.lee@...sung.com" <cw9316.lee@...sung.com>,
        "sh8267.baek@...sung.com" <sh8267.baek@...sung.com>,
        "wkon.kim@...sung.com" <wkon.kim@...sung.com>,
        "seunghwan.hyun@...sung.com" <seunghwan.hyun@...sung.com>
Subject: RE: [PATCH] scsi: ufs: no sw reset after last linkstartup fail

 
> As we know, the ufs host controller is disabled and enabled in the
> ufshcd_hba_enable(). So, host controller registers are clear after sw reset.
> 
> Once the host fails to link startup 3 times, all host's controller can be clear due
> to executing last ufshcd_hba_enable()(s/w reset).
> That's why we need to skip last sw reset to get valid host register values.
> 
> Before
> (ufshcd_dme_link_startup() -> ufshcd_hba_enable() -> retries--) * 3 times.
> 
> After
> (ufshcd_dme_link_startup() -> if retries is 0, break. ->  ufshcd_hba_enable()
> -> retries--) * 3 times.
> In this case, ufshcd_print_host_state(), ufshcd_print_pwr_info(),
> ufshcd_print_evt_hist() are valid.
If you find it necessary to elaborate the commit log, why not do just that?
Also maybe make the title more indicative of what you want to achieve:
"skip last hci reset to get valid register values" or something.

Thanks,
Avri


> 
> > -----Original Message-----
> > From: Seunghui Lee <sh043.lee@...sung.com>
> > Sent: Thursday, June 30, 2022 1:48 PM
> > To: alim.akhtar@...sung.com; avri.altman@....com;
> bvanassche@....org;
> > jejb@...ux.ibm.com; martin.petersen@...cle.com; linux-
> scsi@...r.kernel.org;
> > linux-kernel@...r.kernel.org
> > Cc: grant.jung@...sung.com; jt77.jang@...sung.com;
> > dh0421.hwang@...sung.com; junwoo80.lee@...sung.com;
> jangsub.yi@...sung.com;
> > cw9316.lee@...sung.com; sh8267.baek@...sung.com;
> wkon.kim@...sung.com;
> > Seunghui Lee <sh043.lee@...sung.com>
> > Subject: [PATCH] scsi: ufs: no sw reset after last linkstartup fail
> >
> > Host driver resets the host(ufshcd_hba_enable) after last linkstartup
> > command failed. All of the member or host dump after linkstartup fail are
> > reset value because of sw reset.
> >
> > Signed-off-by: Junwoo Lee <junwoo80.lee@...sung.com>
> > Signed-off-by: Seunghui Lee <sh043.lee@...sung.com>
> > ---
> >  drivers/ufs/core/ufshcd.c | 2 +-
> >  1 file changed, 1 insertion(+), 1 deletion(-)
> >
> > diff --git a/drivers/ufs/core/ufshcd.c b/drivers/ufs/core/ufshcd.c index
> > 7c1d7bb9c579..2cdc14675443 100644
> > --- a/drivers/ufs/core/ufshcd.c
> > +++ b/drivers/ufs/core/ufshcd.c
> > @@ -4753,7 +4753,7 @@ static int ufshcd_link_startup(struct ufs_hba
> *hba)
> >                * but we can't be sure if the link is up until link startup
> >                * succeeds. So reset the local Uni-Pro and try again.
> >                */
> > -             if (ret && ufshcd_hba_enable(hba)) {
> > +             if (ret && retries && ufshcd_hba_enable(hba)) {
> >                       ufshcd_update_evt_hist(hba,
> >                                              UFS_EVT_LINK_STARTUP_FAIL,
> >                                              (u32)ret);
> > --
> > 2.29.0
>