Date:   Mon, 20 Mar 2023 11:55:58 +0100
From:   Miquel Raynal <miquel.raynal@bootlin.com>
To:     Dmitry Rokosov <ddrokosov@sberdevices.ru>
Cc:     Neil Armstrong <neil.armstrong@linaro.org>,
        Arseniy Krasnov <avkrasnov@sberdevices.ru>,
        Liang Yang <liang.yang@amlogic.com>,
        Richard Weinberger <richard@nod.at>,
        Vignesh Raghavendra <vigneshr@ti.com>,
        Kevin Hilman <khilman@baylibre.com>,
        Jerome Brunet <jbrunet@baylibre.com>,
        Martin Blumenstingl <martin.blumenstingl@googlemail.com>,
        Jianxin Pan <jianxin.pan@amlogic.com>,
        <linux-mtd@lists.infradead.org>,
        <linux-arm-kernel@lists.infradead.org>,
        <linux-amlogic@lists.infradead.org>,
        <linux-kernel@vger.kernel.org>, <kernel@sberdevices.ru>,
        <oxffffaa@gmail.com>
Subject: Re: [RFC PATCH v1] mtd: rawnand: meson: invalidate cache on polling
 ECC bit
Message-ID: <20230320115558.49c5a062@xps-13>
In-Reply-To: <20230320104314.i2stk665xbrleb53@CAB-WSD-L081021>
References: <d4ef0bd6-816e-f6fa-9385-f05f775f0ae2@sberdevices.ru>
        <20f7f1f8-e8f8-b3e1-251e-27db71ab6840@sberdevices.ru>
        <20230313121808.27170d1b@xps-13>
        <dc46c06f-6b36-3c1c-bf96-2ef37e29dfdb@linaro.org>
        <20230320104314.i2stk665xbrleb53@CAB-WSD-L081021>
Organization: Bootlin
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Hi Dmitry,

ddrokosov@sberdevices.ru wrote on Mon, 20 Mar 2023 13:43:14 +0300:

> Hello guys!
>=20
> Was it applied to some nand 'prepare-for-merge' release branch?

Not yet, I'll apply it this week in mtd/fixes, you'll be noticed.

Thanks,
Miqu=C3=A8l

> On Mon, Mar 13, 2023 at 12:23:12PM +0100, Neil Armstrong wrote:
> > On 13/03/2023 12:18, Miquel Raynal wrote: =20
> > > Hi Arseniy,
> > >=20
> > > avkrasnov@sberdevices.ru wrote on Mon, 13 Mar 2023 10:36:11 +0300:
> > >  =20
> > > > Hello,
> > > >=20
> > > > we reproduced this problem on one of our boards. It triggers very r=
are
> > > > when 'usleep_range()' is present, but when sleeping is removed - it=
 fires
> > > > always. I suppose problem is with caching, as 'info_buf' memory is =
mapped by
> > > > 'dma_map_single()'. =20
> > >=20
> > > The fix looks really legitimate, indeed I get that the usleep_range()
> > > might make it work most of the time but not always. Having this bit in
> > > a DMA buf area is a bit strange. Well, the fix LGTM anyway. =20
> >=20
> > Yep it looks legitimate!
> >=20
> > LGTM
> >=20
> >=20
> > Reviewed-by: Neil Armstrong <neil.armstrong@linaro.org>
> >  =20
> > >  =20
> > > >=20
> > > > Thanks, Arseniy
> > > >=20
> > > > On 13.03.2023 10:32, Arseniy Krasnov wrote: =20
> > > > > 'info_buf' memory is cached and driver polls ECC bit in it. This =
bit
> > > > > is set by the NAND controller. If 'usleep_range()' returns before=
 device
> > > > > sets this bit, 'info_buf' will be cached and driver won't see upd=
ate of
> > > > > this bit and will loop forever.
> > > > >=20
> > > > > Fixes: 8fae856c5350 ("mtd: rawnand: meson: add support for Amlogi=
c NAND flash controller")
> > > > > Signed-off-by: Arseniy Krasnov <AVKrasnov@sberdevices.ru>
> > > > > ---
> > > > >   drivers/mtd/nand/raw/meson_nand.c | 8 +++++++-
> > > > >   1 file changed, 7 insertions(+), 1 deletion(-)
> > > > >=20
> > > > > diff --git a/drivers/mtd/nand/raw/meson_nand.c b/drivers/mtd/nand=
/raw/meson_nand.c
> > > > > index 5ee01231ac4c..2c05c08a0eaf 100644
> > > > > --- a/drivers/mtd/nand/raw/meson_nand.c
> > > > > +++ b/drivers/mtd/nand/raw/meson_nand.c
> > > > > @@ -176,6 +176,7 @@ struct meson_nfc {
> > > > >   	dma_addr_t daddr;
> > > > >   	dma_addr_t iaddr;
> > > > > +	u32 info_bytes;
> > > > >   	unsigned long assigned_cs;
> > > > >   };
> > > > > @@ -503,6 +504,7 @@ static int meson_nfc_dma_buffer_setup(struct =
nand_chip *nand, void *databuf,
> > > > >   					 nfc->daddr, datalen, dir);
> > > > >   			return ret;
> > > > >   		}
> > > > > +		nfc->info_bytes =3D infolen;
> > > > >   		cmd =3D GENCMDIADDRL(NFC_CMD_AIL, nfc->iaddr);
> > > > >   		writel(cmd, nfc->reg_base + NFC_REG_CMD);
> > > > > @@ -520,8 +522,10 @@ static void meson_nfc_dma_buffer_release(str=
uct nand_chip *nand,
> > > > >   	struct meson_nfc *nfc =3D nand_get_controller_data(nand);
> > > > >   	dma_unmap_single(nfc->dev, nfc->daddr, datalen, dir);
> > > > > -	if (infolen)
> > > > > +	if (infolen) {
> > > > >   		dma_unmap_single(nfc->dev, nfc->iaddr, infolen, dir);
> > > > > +		nfc->info_bytes =3D 0;
> > > > > +	}
> > > > >   }
> > > > >   static int meson_nfc_read_buf(struct nand_chip *nand, u8 *buf, =
int len)
> > > > > @@ -710,6 +714,8 @@ static void meson_nfc_check_ecc_pages_valid(s=
truct meson_nfc *nfc,
> > > > >   		usleep_range(10, 15);
> > > > >   		/* info is updated by nfc dma engine*/
> > > > >   		smp_rmb();
> > > > > +		dma_sync_single_for_cpu(nfc->dev, nfc->iaddr, nfc->info_bytes,
> > > > > +					DMA_FROM_DEVICE);
> > > > >   		ret =3D *info & ECC_COMPLETE;
> > > > >   	} while (!ret);
> > > > >   } =20
> > >=20
> > >=20
> > > Thanks,
> > > Miqu=C3=A8l =20
> >  =20
>=20