Hi Boris, > -----Original Message----- > From: Boris Brezillon <boris.brezil...@collabora.com> > Sent: Wednesday, June 26, 2019 5:34 PM > To: Naga Sureshkumar Relli <nagas...@xilinx.com> > Cc: miquel.ray...@bootlin.com; helmut.gro...@intenta.de; rich...@nod.at; > dw...@infradead.org; computersforpe...@gmail.com; marek.va...@gmail.com; > vigne...@ti.com; bbrezil...@kernel.org; yamada.masah...@socionext.com; linux- > m...@lists.infradead.org; linux-kernel@vger.kernel.org > Subject: Re: [LINUX PATCH v17 1/2] mtd: rawnand: nand_micron: Do not over > write > driver's read_page()/write_page() > > On Wed, 26 Jun 2019 11:51:12 +0000 > Naga Sureshkumar Relli <nagas...@xilinx.com> wrote: > > > Hi Boris, > > > > > -----Original Message----- > > > From: Boris Brezillon <boris.brezil...@collabora.com> > > > Sent: Wednesday, June 26, 2019 4:57 PM > > > To: Naga Sureshkumar Relli <nagas...@xilinx.com> > > > Cc: miquel.ray...@bootlin.com; helmut.gro...@intenta.de; > > > rich...@nod.at; dw...@infradead.org; computersforpe...@gmail.com; > > > marek.va...@gmail.com; vigne...@ti.com; bbrezil...@kernel.org; > > > yamada.masah...@socionext.com; linux- m...@lists.infradead.org; > > > linux-kernel@vger.kernel.org > > > Subject: Re: [LINUX PATCH v17 1/2] mtd: rawnand: nand_micron: Do not > > > over write driver's read_page()/write_page() > > > > > > On Wed, 26 Jun 2019 11:22:33 +0000 > > > Naga Sureshkumar Relli <nagas...@xilinx.com> wrote: > > > > > > > Hi Boris, > > > > > > > > > -----Original Message----- > > > > > From: Boris Brezillon <boris.brezil...@collabora.com> > > > > > Sent: Wednesday, June 26, 2019 12:18 PM > > > > > To: Naga Sureshkumar Relli <nagas...@xilinx.com> > > > > > Cc: miquel.ray...@bootlin.com; helmut.gro...@intenta.de; > > > > > rich...@nod.at; dw...@infradead.org; > > > > > computersforpe...@gmail.com; marek.va...@gmail.com; > > > > > vigne...@ti.com; bbrezil...@kernel.org; > > > > > yamada.masah...@socionext.com; linux- m...@lists.infradead.org; > > > > > linux-kernel@vger.kernel.org > > > > > Subject: Re: [LINUX PATCH v17 1/2] mtd: rawnand: nand_micron: Do > > > > > not over write driver's read_page()/write_page() > > > > > > > > > > On Mon, 24 Jun 2019 22:46:29 -0600 Naga Sureshkumar Relli > > > > > <naga.sureshkumar.re...@xilinx.com> wrote: > > > > > > > > > > > Add check before assigning chip->ecc.read_page() and > > > > > > chip->ecc.write_page() > > > > > > > > > > > > Signed-off-by: Naga Sureshkumar Relli > > > > > > <naga.sureshkumar.re...@xilinx.com> > > > > > > --- > > > > > > drivers/mtd/nand/raw/nand_micron.c | 7 +++++-- > > > > > > 1 file changed, 5 insertions(+), 2 deletions(-) > > > > > > > > > > > > diff --git a/drivers/mtd/nand/raw/nand_micron.c > > > > > > b/drivers/mtd/nand/raw/nand_micron.c > > > > > > index cbd4f09ac178..565f2696c747 100644 > > > > > > --- a/drivers/mtd/nand/raw/nand_micron.c > > > > > > +++ b/drivers/mtd/nand/raw/nand_micron.c > > > > > > @@ -500,8 +500,11 @@ static int micron_nand_init(struct nand_chip > > > > > > *chip) > > > > > > chip->ecc.size = 512; > > > > > > chip->ecc.strength = chip->base.eccreq.strength; > > > > > > chip->ecc.algo = NAND_ECC_BCH; > > > > > > - chip->ecc.read_page = micron_nand_read_page_on_die_ecc; > > > > > > - chip->ecc.write_page = > > > > > > micron_nand_write_page_on_die_ecc; > > > > > > + if (!chip->ecc.read_page) > > > > > > + chip->ecc.read_page = > > > > > > micron_nand_read_page_on_die_ecc; > > > > > > + > > > > > > + if (!chip->ecc.write_page) > > > > > > + chip->ecc.write_page = > > > > > > micron_nand_write_page_on_die_ecc; > > > > > > > > > > That's wrong, if you don't want on-die ECC to be used, simply > > > > > don't set nand-ecc-mode to "on- die". > > > > Ok. But if we want to use on-die ECC then you mean to say it is > > > > mandatory to use > > > micron_nand_read/write_page_on_die_ecc()? > > > > > > Absolutely, and if it doesn't work that means you driver does not > > > implement raw accesses correctly, which means it's still buggy... > > I agree. But let's say, if there is a limitation with the controller. Then > > it is must to have this > check right? > > I mean, for pl353 controller, we must clear the CS during the data > > phase, hence we are splitting the Transfer in the > > pl353_read/write_page_raw(). > > + pl353_nand_read_data_op(chip, buf, mtd->writesize, false); > > + p = chip->oob_poi; > > + pl353_nand_read_data_op(chip, p, > > + (mtd->oobsize - > > + PL353_NAND_LAST_TRANSFER_LENGTH), false); > > + p += (mtd->oobsize - PL353_NAND_LAST_TRANSFER_LENGTH); > > + xnfc->dataphase_addrflags |= PL353_NAND_CLEAR_CS; > > + pl353_nand_read_data_op(chip, p, PL353_NAND_LAST_TRANSFER_LENGTH, > > + false); > > As the above sequence is needed even for raw access, PL353 is unable to use > > the on_die_page > reads. > > This "de-assert CS on last access" logic should be done in the > exec_op() implementation. I also wonder how that works for operations that > don't have data > cycles. Oh, BTW, most chips are CE-don't-care, which means you can > assert/de-assert CS on > each read_data_op() without any issues. Yes, we can assert/de-assert CS on each read/write_data_op(). But what about transfer length splitting? + p = chip->oob_poi; + pl353_nand_read_data_op(chip, p, + (mtd->oobsize - + PL353_NAND_LAST_TRANSFER_LENGTH), false); + p += (mtd->oobsize - PL353_NAND_LAST_TRANSFER_LENGTH); This should be done as a part of pl353_raw_read/write() right?
Thanks, Naga Sureshkumar Relli
