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Date:   Thu, 12 Dec 2019 10:24:11 -0800
From:   Bjorn Andersson <bjorn.andersson@linaro.org>
To:     cang@codeaurora.org
Cc:     Avri Altman <Avri.Altman@wdc.com>, asutoshd@codeaurora.org,
        nguyenb@codeaurora.org, rnayak@codeaurora.org,
        linux-scsi@vger.kernel.org, kernel-team@android.com,
        saravanak@google.com, salyzyn@google.com,
        Alim Akhtar <alim.akhtar@samsung.com>,
        Pedro Sousa <pedrom.sousa@synopsys.com>,
        "James E.J. Bottomley" <jejb@linux.ibm.com>,
        "Martin K. Petersen" <martin.petersen@oracle.com>,
        Evan Green <evgreen@chromium.org>,
        Kishon Vijay Abraham I <kishon@ti.com>,
        Stephen Boyd <swboyd@chromium.org>,
        Stanley Chu <stanley.chu@mediatek.com>,
        Vignesh Raghavendra <vigneshr@ti.com>,
        Bean Huo <beanhuo@micron.com>,
        Bart Van Assche <bvanassche@acm.org>,
        Venkat Gopalakrishnan <venkatg@codeaurora.org>,
        Tomas Winkler <tomas.winkler@intel.com>,
        Arnd Bergmann <arnd@arndb.de>,
        open list <linux-kernel@vger.kernel.org>
Subject: Re: [PATCH v2 2/3] scsi: ufs: Modulize ufs-bsg
Message-ID: <20191212182411.GE415177@yoga>
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On Thu 12 Dec 08:53 PST 2019, cang@codeaurora.org wrote:

> On 2019-12-12 15:00, Avri Altman wrote:
> > > On Wed 11 Dec 22:01 PST 2019, cang@codeaurora.org wrote:
> > > > On 2019-12-12 12:53, Bjorn Andersson wrote:
> > > > > On Wed 11 Dec 00:49 PST 2019, Can Guo wrote:
[..]
> > > > And in real cases, as the UFS is the boot device, UFS driver will always
> > > > be probed during bootup.
> > > >
> > > 
> > > The UFS driver will load and probe because it's mentioned in the
> > > devicetree, but if either the ufs drivers or any of its dependencies
> > > (phy, resets, clocks, etc) are built as modules it might very well
> > > finish probing after lateinitcall.
> > > 
> > > So in the even that the bsg is =y and any of these drivers are =m,
> > > or if
> > > you're having bad luck with your timing, the list will be empty.
> > > 
> > > As described below, if bsg=m, then there's nothing that will load the
> > > module and the bsg will not probe...
> > Right.
> > bsg=y and ufshcd=m is a bad idea, and should be avoided.
> > 
> 
> Yeah, I will get it addressed in the next patchset.
> 

If you build this around platform_device_register_data() from ufshcd I
don't see a reason to add additional restrictions on this combination
(even though it might not make much sense for people to use this
combination).

Regards,
Bjorn