From: Miquel Raynal <miquel.raynal@bootlin.com>
To: Pratyush Yadav <p.yadav@ti.com>
Cc: <patrice.chotard@foss.st.com>, Mark Brown <broonie@kernel.org>,
Vignesh Raghavendra <vigneshr@ti.com>,
Boris Brezillon <boris.brezillon@collabora.com>,
<linux-mtd@lists.infradead.org>,
Alexandre Torgue <alexandre.torgue@foss.st.com>,
<linux-spi@vger.kernel.org>,
<linux-stm32@st-md-mailman.stormreply.com>,
<linux-arm-kernel@lists.infradead.org>,
<linux-kernel@vger.kernel.org>, <christophe.kerello@foss.st.com>
Subject: Re: mtd: spinand: add spi nand mtd resume handler
Date: Thu, 27 May 2021 12:04:23 +0200 [thread overview]
Message-ID: <20210527120423.7bf18966@xps13> (raw)
In-Reply-To: <20210527100015.abxcroi23zyvcyzk@ti.com>
Hi Pratyush,
Pratyush Yadav <p.yadav@ti.com> wrote on Thu, 27 May 2021 15:30:17
+0530:
> On 26/05/21 05:30PM, patrice.chotard@foss.st.com wrote:
> > From: Christophe Kerello <christophe.kerello@foss.st.com>
> >
> > After power up, all SPI NAND's blocks are locked. Only read operations
> > are allowed, write and erase operations are forbidden.
> > The SPI NAND framework unlocks all the blocks during its initialization.
> >
> > During a standby low power, the memory is powered down, losing its
> > configuration.
> > During the resume, the QSPI driver state is restored but the SPI NAND
> > framework does not reconfigured the memory.
> >
> > This patch adds spi nand mtd PM handlers for resume ops.
> > SPI NAND resume op re-initializes SPI NAND flash to its probed state.
> >
> > Signed-off-by: Christophe Kerello <christophe.kerello@foss.st.com>
> > Signed-off-by: Patrice Chotard <patrice.chotard@foss.st.com>
> > ---
> > drivers/mtd/nand/spi/core.c | 56 +++++++++++++++++++++++++++++++++++++
> > 1 file changed, 56 insertions(+)
> >
> > diff --git a/drivers/mtd/nand/spi/core.c b/drivers/mtd/nand/spi/core.c
> > index 17f63f95f4a2..6abaf874eb3f 100644
> > --- a/drivers/mtd/nand/spi/core.c
> > +++ b/drivers/mtd/nand/spi/core.c
> > @@ -1074,6 +1074,61 @@ static int spinand_detect(struct spinand_device *spinand)
> > return 0;
> > }
> >
> > +static void spinand_mtd_resume(struct mtd_info *mtd)
> > +{
> > + struct spinand_device *spinand = mtd_to_spinand(mtd);
> > + struct nand_device *nand = mtd_to_nanddev(mtd);
> > + struct device *dev = &spinand->spimem->spi->dev;
> > + int ret, i;
> > +
> > + ret = spinand_reset_op(spinand);
> > + if (ret)
> > + return;
> > +
> > + ret = spinand_init_quad_enable(spinand);
> > + if (ret) {
> > + dev_err(dev,
> > + "Failed to initialize the quad part (err = %d)\n",
> > + ret);
> > + return;
> > + }
> > +
> > + ret = spinand_upd_cfg(spinand, CFG_OTP_ENABLE, 0);
> > + if (ret) {
> > + dev_err(dev,
> > + "Failed to updtae the OTP (err = %d)\n",
> > + ret);
> > + return;
> > + }
>
> Since you have reset the flash, this cache is invalid. You should reset
> the cache and re-populate it before using it in any way.
>
> > +
> > + ret = spinand_manufacturer_init(spinand);
> > + if (ret) {
> > + dev_err(dev,
> > + "Failed to initialize the SPI NAND chip (err = %d)\n",
> > + ret);
> > + return;
> > + }
> > +
> > + /* After power up, all blocks are locked, so unlock them here. */
> > + for (i = 0; i < nand->memorg.ntargets; i++) {
> > + ret = spinand_select_target(spinand, i);
> > + if (ret) {
> > + dev_err(dev,
> > + "Failed to select the target (err = %d)\n",
> > + ret);
> > + return;
> > + }
> > +
> > + ret = spinand_lock_block(spinand, BL_ALL_UNLOCKED);
> > + if (ret) {
> > + dev_err(dev,
> > + "Failed to unlock block (err = %d)\n",
> > + ret);
> > + return;
> > + }
> > + }
> > +}
> > +
>
> Most of these seem to be copied from spinand_init(). I think it is
> better to create a common function that can be called from both
> spinand_init() and spinand_mtd_resume(). This way when someone adds
> something new to the init procedure, like support for some other modes,
> they won't have to remember to update it in two places.
Agreed, let's write a common helper for more than just the unlocking
sequence (still in a separate patch).
>
> > static int spinand_init(struct spinand_device *spinand)
> > {
> > struct device *dev = &spinand->spimem->spi->dev;
> > @@ -1167,6 +1222,7 @@ static int spinand_init(struct spinand_device *spinand)
> > mtd->_block_isreserved = spinand_mtd_block_isreserved;
> > mtd->_erase = spinand_mtd_erase;
> > mtd->_max_bad_blocks = nanddev_mtd_max_bad_blocks;
> > + mtd->_resume = spinand_mtd_resume;
>
> Is it possible that the userspace can use this mtd device before the
> resume is finished? Is there a way to temporarily "pause" or unregister
> an mtd device?
I don't expect this to happen, I would expect the kernel to resume
entirely before giving the hand to userspace, but I am not 100% sure of
that neither.
>
> >
> > if (nand->ecc.engine) {
> > ret = mtd_ooblayout_count_freebytes(mtd);
>
Thanks,
Miquèl
next prev parent reply other threads:[~2021-05-27 10:04 UTC|newest]
Thread overview: 7+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-05-26 15:30 mtd: spinand: add spi nand mtd resume handler patrice.chotard
2021-05-26 15:42 ` Miquel Raynal
2021-05-27 7:01 ` Patrice CHOTARD
2021-05-27 7:32 ` [Linux-stm32] " Patrice CHOTARD
2021-05-27 10:00 ` Pratyush Yadav
2021-05-27 10:04 ` Miquel Raynal [this message]
2021-05-27 13:50 ` Patrice CHOTARD
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