Re: [PATCH v4 3/5] mtd: handle partitioning on devices with 0 erasesize

Boris Brezillon
2017-05-29T09:14:21Z

On Thu, 25 May 2017 11:49:14 +1200
Chris Packham <chris.packham@alliedtelesis.co.nz> wrote:

> erasesize is meaningful for flash devices but for SRAM there is no
> concept of an erase block so erasesize is set to 0. When partitioning
> these devices instead of ensuring partitions fall on erasesize
> boundaries we ensure they fall on writesize boundaries.
>
> Helped-by: Boris Brezillon <boris.brezillon@free-electrons.com>
> Signed-off-by: Chris Packham <chris.packham@alliedtelesis.co.nz>

Acked-by: Boris Brezillon <boris.brezillon@free-electrons.com>

> ---
> Changes in v3:
> - new
> Changes in v4:
> - None
>
> drivers/mtd/mtdpart.c | 25 ++++++++++++++++---------
> 1 file changed, 16 insertions(+), 9 deletions(-)
>
> diff --git a/drivers/mtd/mtdpart.c b/drivers/mtd/mtdpart.c
> index ea5e5307f667..5cef1247806c 100644
> --- a/drivers/mtd/mtdpart.c
> +++ b/drivers/mtd/mtdpart.c
> @@ -393,8 +393,11 @@ static struct mtd_part *allocate_partition(struct mtd_info *master,
> const struct mtd_partition *part, int partno,
> uint64_t cur_offset)
> {
> + int wr_alignment = master->erasesize ? : master->writesize;
> struct mtd_part *slave;
> + u32 remainder;
> char *name;
> + u64 tmp;
>
> /* allocate the partition structure */
> slave = kzalloc(sizeof(*slave), GFP_KERNEL);
> @@ -499,10 +502,11 @@ static struct mtd_part *allocate_partition(struct mtd_info *master,
> if (slave->offset == MTDPART_OFS_APPEND)
> slave->offset = cur_offset;
> if (slave->offset == MTDPART_OFS_NXTBLK) {
> + tmp = cur_offset;
> slave->offset = cur_offset;
> - if (mtd_mod_by_eb(cur_offset, master) != 0) {
> - /* Round up to next erasesize */
> - slave->offset = (mtd_div_by_eb(cur_offset, master) + 1) * master->erasesize;
> + remainder = do_div(tmp, wr_alignment);
> + if (remainder) {
> + slave->offset += wr_alignment - remainder;
> printk(KERN_NOTICE "Moving partition %d: "
> "0x%012llx -> 0x%012llx\n", partno,
> (unsigned long long)cur_offset, (unsigned long long)slave->offset);
> @@ -567,19 +571,22 @@ static struct mtd_part *allocate_partition(struct mtd_info *master,
> slave->mtd.erasesize = master->erasesize;
> }
>
> - if ((slave->mtd.flags & MTD_WRITEABLE) &&
> - mtd_mod_by_eb(slave->offset, &slave->mtd)) {
> + tmp = slave->offset;
> + remainder = do_div(tmp, wr_alignment);
> + if ((slave->mtd.flags & MTD_WRITEABLE) && remainder) {
> /* Doesn't start on a boundary of major erase size */
> /* FIXME: Let it be writable if it is on a boundary of
> * _minor_ erase size though */
> slave->mtd.flags &= ~MTD_WRITEABLE;
> - printk(KERN_WARNING"mtd: partition \"%s\" doesn't start on an erase block boundary -- force read-only\n",
> + printk(KERN_WARNING"mtd: partition \"%s\" doesn't start on an erase/write block boundary -- force read-only\n",
> part->name);
> }
> - if ((slave->mtd.flags & MTD_WRITEABLE) &&
> - mtd_mod_by_eb(slave->mtd.size, &slave->mtd)) {
> +
> + tmp = slave->mtd.size;
> + remainder = do_div(tmp, wr_alignment);
> + if ((slave->mtd.flags & MTD_WRITEABLE) && remainder) {
> slave->mtd.flags &= ~MTD_WRITEABLE;
> - printk(KERN_WARNING"mtd: partition \"%s\" doesn't end on an erase block -- force read-only\n",
> + printk(KERN_WARNING"mtd: partition \"%s\" doesn't end on an erase/write block -- force read-only\n",
> part->name);
> }
>