Re: [PATCH 3/4] mtd: mchp23k256: add partitioning support

Chris Packham
2017-05-22T04:52:42Z

On 18/05/17 03:29, Boris Brezillon wrote:
> Hi Chris,
>
> On Wed, 17 May 2017 17:39:07 +1200
> Chris Packham <chris.packham@alliedtelesis.co.nz> wrote:
>
>> Setting the of_node for the mtd device allows the generic mtd code to
>> setup the partitions. Additionally we must specify a non-zero erasesize
>> for the partitions to be writeable.
>>
>> Signed-off-by: Chris Packham <chris.packham@alliedtelesis.co.nz>
>> ---
>> drivers/mtd/devices/mchp23k256.c | 5 +++++
>> 1 file changed, 5 insertions(+)
>>
>> diff --git a/drivers/mtd/devices/mchp23k256.c b/drivers/mtd/devices/mchp23k256.c
>> index 2542f5b8b63f..02c6b9dcbd3e 100644
>> --- a/drivers/mtd/devices/mchp23k256.c
>> +++ b/drivers/mtd/devices/mchp23k256.c
>> @@ -143,6 +143,7 @@ static int mchp23k256_probe(struct spi_device *spi)
>>
>> data = dev_get_platdata(&spi->dev);
>>
>> + mtd_set_of_node(&flash->mtd, spi->dev.of_node);
>> flash->mtd.dev.parent = &spi->dev;
>> flash->mtd.type = MTD_RAM;
>> flash->mtd.flags = MTD_CAP_RAM;
>> @@ -151,6 +152,10 @@ static int mchp23k256_probe(struct spi_device *spi)
>> flash->mtd._read = mchp23k256_read;
>> flash->mtd._write = mchp23k256_write;
>>
>> + flash->mtd.erasesize = PAGE_SIZE;
>> + while (flash->mtd.size & (flash->mtd.erasesize - 1))
>> + flash->mtd.erasesize >>= 1;
>> +
>
> Can we fix allocate_partition() to properly handle the
> master->erasesize == 0 case instead of doing that?
>

Do you mean something like this?

diff --git a/drivers/mtd/mtdpart.c b/drivers/mtd/mtdpart.c
index ea5e5307f667..0cd20ed6b374 100644
--- a/drivers/mtd/mtdpart.c
+++ b/drivers/mtd/mtdpart.c
@@ -577,6 +577,7 @@ static struct mtd_part *allocate_partition(struct
mtd_info *master,
part->name);
}
if ((slave->mtd.flags & MTD_WRITEABLE) &&
+ master->erasesize != 0 &&
mtd_mod_by_eb(slave->mtd.size, &slave->mtd)) {
slave->mtd.flags &= ~MTD_WRITEABLE;

I'm happy to submit this as a formal patch but it could potentially
affect a number of devices. Whereas the snippet I initially added is
consistent with drivers/mtd/chips/map_ram.c.

For now I'll leave v2 as-is but I can send a v3 if needed.