On Wednesday, August 10, 2011 12:37:29 AM Scott Wood wrote:
On 08/09/2011 04:54 PM, Marek Vasut wrote:
Don't allocate NAND buffers as one block, but allocate them separately. This allows systems where DMA to buffers happen to allocate these buffers properly aligned.
Signed-off-by: Marek Vasut marek.vasut@gmail.com
That second sentence is hard to parse -- I think you mean something like, "This accommodates drivers which DMA to the buffers and have alignment constraints."
Yes, something like that. Sorry, it's 1.14 PM here.
Will a similar change be needed in Linux?
I'm not sure how much in sync we are with linux here. It'd be worth looking at.
int nand_scan_tail(struct mtd_info *mtd) {
- int i;
int i, bufsize;
uint8_t *buf;
struct nand_chip *chip = mtd->priv;
- if (!(chip->options & NAND_OWN_BUFFERS))
chip->buffers = kmalloc(sizeof(*chip->buffers), GFP_KERNEL);- if (!chip->buffers)
- if (!(chip->options & NAND_OWN_BUFFERS)) {
chip->buffers = malloc(sizeof(struct nand_buffers));if (!chip->buffers)return -ENOMEM;Why does the struct itself need to be dynamically allocated?
That was in the NOTE: ... to avoid breaking drivers. We can have that changed, but that'd be much more intrussive.
bufsize = NAND_MAX_PAGESIZE + (3 * NAND_MAX_OOBSIZE);buf = malloc(bufsize);chip->buffers->buffer = (struct nand_buffers *)buf;chip->buffers->ecccalc = buf;chip->buffers->ecccode = buf + NAND_MAX_OOBSIZE;chip->buffers->databuf = buf + (2 * NAND_MAX_OOBSIZE);}
if (!chip->buffers->buffer)
return -ENOMEM;
What does "buffer" mean now? What would a driver that supplies its own completely separate ecccalc/ecccode/databuf buffers put in "buffer"?
Maybe that condition should go also into the if() statement above. What do you think ?
-Scott