Re: [PATCH] fix for mtd partitions for erase_size != 2^X

Peter Menzebach
2005-09-30T11:34:20Z

Jörn Engel wrote:
> On Fri, 23 September 2005 20:02:42 +0200, Peter Menzebach wrote:
>
>>Here a trivial patch,
>>which allows correct creation of mtd partitions, which have erase sizes
>>which are not a power of 2.
>>
>>Best regards
>>Peter
>>
>>Sorry, I didn't succeed to get the patch accepted by the mailing list as
>>attachment.
>
>
> I actually prefer inline. Except that your mailer seems to have
> messed things up - grr.
>
>
>>--- drivers/mtd/mtdpart.c.orig 2005-09-23 09:28:07.000000000 +0200
>>+++ drivers/mtd/mtdpart.c 2005-09-23 09:29:37.000000000 +0200
>>@@ -465,9 +465,9 @@
>> if (slave->offset == MTDPART_OFS_APPEND)
>> slave->offset = cur_offset;
>> if (slave->offset == MTDPART_OFS_NXTBLK) {
>>- u_int32_t emask = master->erasesize-1;
>>- slave->offset = (cur_offset + emask) & ~emask;
>>- if (slave->offset != cur_offset) {
>>+ slave->offset = cur_offset;
>>+ if ((cur_offset % master->erasesize) != 0) {
>>+ slave->offset = ((cur_offset / master->erasesize) + 1)
>>* master->erasesize;
>> printk(KERN_NOTICE "Moving partition %d: "
>> "0x%08x -> 0x%08x\n", i,
>> cur_offset, slave->offset);
>
>
> Looks complicated. I guess we could use the equivalent of this:
> #define ALIGN(x,a) (((x)+(a)-1)&~((a)-1))
> in some header. Then your patch would be as simple as
>
> if (slave->offset == MTDPART_OFS_APPEND)
> slave->offset = cur_offset;
> if (slave->offset == MTDPART_OFS_NXTBLK) {
> - u_int32_t emask = master->erasesize-1;
> - slave->offset = (cur_offset + emask) & ~emask;
> + slave->offset = TRUE_ALIGN(cur_offset, master->erasesize);
> if (slave->offset != cur_offset) {
> printk(KERN_NOTICE "Moving partition %d: "
> "0x%08x -> 0x%08x\n", i,
>
> Maybe this:
> #define TRUE_ALIGN(x,a) (((x)+(a)-1) - ((x)+(a)-1) % a)
>
> The macro is still complicated, but we just have to get it right once.
>
> Jörn
>
Here the patch again. As the macro does not seem to reduce the
complexity of the line seriously and would be used only once, I did put
in a comment, which explains inline, what should go on there.

The patch now as link:
http://www.mw-itcon.de/patches/patch.dataflash.mtdpart.c

Best regards
Peter

--
Peter Menzebach
Menzebach und Wolff IT-Consulting GbR
Phone +49 751 355 387 1