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Message-ID: <62aa16f6.1c69fb81.816fc.be7a@mx.google.com>
Date: Wed, 15 Jun 2022 18:35:26 +0200
From: Ansuel Smith <ansuelsmth@...il.com>
To: Manivannan Sadhasivam <mani@...nel.org>
Cc: Andy Gross <agross@...nel.org>,
Bjorn Andersson <bjorn.andersson@...aro.org>,
Miquel Raynal <miquel.raynal@...tlin.com>,
Richard Weinberger <richard@....at>,
Vignesh Raghavendra <vigneshr@...com>,
Rob Herring <robh+dt@...nel.org>,
Krzysztof Kozlowski <krzysztof.kozlowski+dt@...aro.org>,
linux-mtd@...ts.infradead.org, linux-arm-msm@...r.kernel.org,
devicetree@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH v7 2/3] mtd: nand: raw: qcom_nandc: add support for
unprotected spare data pages
On Wed, Jun 15, 2022 at 10:58:02PM +0530, Manivannan Sadhasivam wrote:
> On Wed, Jun 15, 2022 at 02:06:11AM +0200, Ansuel Smith wrote:
> > IPQ8064 nand have special pages where a different layout scheme is used.
> > These special page are used by boot partition and on reading them
> > lots of warning are reported about wrong ECC data and if written to
> > results in broken data and not bootable device.
> >
> > The layout scheme used by these special page consist in using 512 bytes
> > as the codeword size (even for the last codeword) while writing to CFG0
> > register. This forces the NAND controller to unprotect the 4 bytes of
> > spare data.
> >
> > Since the kernel is unaware of this different layout for these special
> > page, it does try to protect the spare data too during read/write and
> > warn about CRC errors.
> >
> > Add support for this by permitting the user to declare these special
> > pages in dts by declaring offset and size of the partition. The driver
> > internally will convert these value to nand pages.
> >
> > On user read/write the page is checked and if it's a boot page the
> > correct layout is used.
> >
> > Signed-off-by: Ansuel Smith <ansuelsmth@...il.com>
>
> Just a few nitpicks below. With those fixed,
>
> Reviewed-by: Manivannan Sadhasivam <mani@...nel.org>
>
> Thanks,
> Mani
>
Sure! Thanks a lot for the various review. Will send v8 that should be
the final version.
> > ---
> > drivers/mtd/nand/raw/qcom_nandc.c | 203 +++++++++++++++++++++++++++++-
> > 1 file changed, 198 insertions(+), 5 deletions(-)
> >
> > diff --git a/drivers/mtd/nand/raw/qcom_nandc.c b/drivers/mtd/nand/raw/qcom_nandc.c
> > index f2990d721733..0dbfe32888ff 100644
> > --- a/drivers/mtd/nand/raw/qcom_nandc.c
> > +++ b/drivers/mtd/nand/raw/qcom_nandc.c
>
> [...]
>
> > +static bool qcom_nandc_is_boot_partition(struct qcom_nand_host *host, int page)
> > +{
> > + struct qcom_nand_boot_partition *boot_partition;
> > + u32 start, end;
> > + int i;
> > +
> > + /*
> > + * Since the frequent access will be to the non-boot partitions like rootfs,
> > + * optimize the page check by:
> > +
>
> Missing "*"
>
> > + * 1. Checking if the page lies after the last boot partition.
> > + * 2. Checking from the boot partition end.
> > + */
> > +
> > + /* First check the last boot partition */
> > + boot_partition = &host->boot_partitions[host->nr_boot_partitions - 1];
> > + start = boot_partition->page_offset;
> > + end = start + boot_partition->page_size;
> > +
> > + /* Page is after the last boot partition end. This is NOT a boot partition */
> > + if (page > end)
> > + return false;
> > +
> > + /* Actually check if it's a boot partition */
> > + if (page < end && page >= start)
> > + return true;
> > +
> > + /* Check the other boot partition starting from the second-last partition */
>
> s/boot partition/boot partitions
>
> > + for (i = host->nr_boot_partitions - 2; i >= 0; i--) {
> > + boot_partition = &host->boot_partitions[i];
> > + start = boot_partition->page_offset;
> > + end = start + boot_partition->page_size;
> > +
> > + if (page < end && page >= start)
> > + return true;
> > + }
> > +
> > + return false;
> > +}
> > +
> > +static void
> > +qcom_nandc_codeword_fixup(struct qcom_nand_host *host, int page)
>
> As like other functions, please align the function on the same line
>
> > +{
> > + bool codeword_fixup = qcom_nandc_is_boot_partition(host, page);
> > +
> > + /* Skip conf write if we are already in the correct mode */
> > + if (codeword_fixup == host->codeword_fixup)
> > + return;
> > +
> > + host->codeword_fixup = codeword_fixup;
> > +
> > + host->cw_data = codeword_fixup ? 512 : 516;
> > + host->spare_bytes = host->cw_size - host->ecc_bytes_hw -
> > + host->bbm_size - host->cw_data;
> > +
> > + host->cfg0 &= ~(SPARE_SIZE_BYTES_MASK | UD_SIZE_BYTES_MASK);
> > + host->cfg0 |= host->spare_bytes << SPARE_SIZE_BYTES |
> > + host->cw_data << UD_SIZE_BYTES;
> > +
> > + host->ecc_bch_cfg &= ~ECC_NUM_DATA_BYTES_MASK;
> > + host->ecc_bch_cfg |= host->cw_data << ECC_NUM_DATA_BYTES;
> > + host->ecc_buf_cfg = (host->cw_data - 1) << NUM_STEPS;
> > +}
>
> [...]
>
> > +static int qcom_nand_host_parse_boot_partitions(struct qcom_nand_controller *nandc,
> > + struct qcom_nand_host *host,
> > + struct device_node *dn)
> > +{
> > + struct nand_chip *chip = &host->chip;
> > + struct mtd_info *mtd = nand_to_mtd(chip);
> > + struct qcom_nand_boot_partition *boot_partition;
> > + struct device *dev = nandc->dev;
> > + int partitions_count, i, j, ret;
> > +
> > + if (!of_find_property(dn, "qcom,boot-partitions", NULL))
> > + return 0;
> > +
> > + partitions_count = of_property_count_u32_elems(dn, "qcom,boot-partitions");
> > + if (partitions_count <= 0) {
> > + dev_err(dev, "Error parsing boot partition\n");
> > + if (partitions_count == 0)
> > + return -EINVAL;
> > + else
> > + return partitions_count;
>
> return partitions_count ? partitions_count : -EINVAL;
>
> Thanks,
> Mani
>
> --
> மணிவண்ணன் சதாசிவம்
--
Ansuel
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