linux-kernel - Re: [PATCH v3 2/2] mtd: nand: raw: brcmnand: When oops in progress use pio and interrupt polling

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Message-ID: <CAC=U0a3co4Ju94pEp4exDYNz=G7YnEztjdZWSjOBKTL+C_7g8Q@mail.gmail.com>
Date:   Tue, 11 Jun 2019 16:03:21 -0400
From:   Kamal Dasu <kdasu.kdev@...il.com>
To:     Richard Weinberger <richard.weinberger@...il.com>
Cc:     MTD Maling List <linux-mtd@...ts.infradead.org>,
        Vignesh Raghavendra <vigneshr@...com>,
        Richard Weinberger <richard@....at>,
        LKML <linux-kernel@...r.kernel.org>,
        Marek Vasut <marek.vasut@...il.com>,
        bcm-kernel-feedback-list@...adcom.com,
        Miquel Raynal <miquel.raynal@...tlin.com>,
        Brian Norris <computersforpeace@...il.com>,
        David Woodhouse <dwmw2@...radead.org>
Subject: Re: [PATCH v3 2/2] mtd: nand: raw: brcmnand: When oops in progress
 use pio and interrupt polling

Richard,

You have any other review comments/concerns with this patch, if not
can you please sign off on it.

Thanks
Kamal

On Fri, May 17, 2019 at 7:56 AM Kamal Dasu <kdasu.kdev@...il.com> wrote:
>
> On Fri, May 17, 2019 at 4:12 AM Richard Weinberger
> <richard.weinberger@...il.com> wrote:
> >
> > On Thu, May 16, 2019 at 6:42 PM Kamal Dasu <kdasu.kdev@...il.com> wrote:
> > >
> > > If mtd_oops is in progress, switch to polling during NAND command
> > > completion instead of relying on DMA/interrupts so that the mtd_oops
> > > buffer can be completely written in the assigned NAND partition.
> >
> > With the new flag the semantics change, as soon a panic write happened,
> > the flag will stay and *all* future operates will take the polling/pio path.
> >
>
> Yes that is true.
>
> > IMHO this is fine since the kernel cannot recover from an oops.
> > But just to make sure we all get this. :-)
> > An alternative would be to block all further non-panic writes.
>
> Capturing the panic writes into an mtd device reliably is what the low
> level driver is trying to do.If there are non panic writes they will
> use pio and interrupt  polling  as well in this case.
>
> > --
> > Thanks,
> > //richard
>
> Thanks
> Kamal