mtd: docg4: fix oob reads

This patch does two closely related things:

(1) Currently the ecc.read_page() method does not fill the nand->oob_poi buffer
with the oob data, but instead reads oob into a local buffer.  Fix this by
filling the oob_poi buffer instead of a local buffer.  The 'oob_required'
argument is quietly ignored; the device must always read oob after the page
data, and it is presumed that there's no harm in filling oob_poi, even when not
explicitly requested.

(2) Always read oob from the device in ecc.read_oob(), instead of copying it
from a local buffer under some circumstances.

Signed-off-by: Mike Dunn <mikedunn@newsguy.com>
Signed-off-by: Artem Bityutskiy <artem.bityutskiy@linux.intel.com>
Signed-off-by: David Woodhouse <David.Woodhouse@intel.com>

1 files changed, 6 insertions, 27 deletions

diff --git a/drivers/mtd/nand/docg4.c b/drivers/mtd/nand/docg4.c
index 0f2ffd7b6c82..793921e56f8e 100644
--- a/drivers/mtd/nand/docg4.c
+++ b/drivers/mtd/nand/docg4.c
@@ -378,9 +378,9 @@ static int correct_data(struct mtd_info *mtd, uint8_t *buf, int page)
                  * bit flips(s) are not reported in stats.
                  */
 
-                if (doc->oob_buf[15]) {
+                if (nand->oob_poi[15]) {
                         int bit, numsetbits = 0;
-                        unsigned long written_flag = doc->oob_buf[15];
+                        unsigned long written_flag = nand->oob_poi[15];
                         for_each_set_bit(bit, &written_flag, 8)
                                 numsetbits++;
                         if (numsetbits > 4) { /* assume blank */
@@ -428,7 +428,7 @@ static int correct_data(struct mtd_info *mtd, uint8_t *buf, int page)
                 /* if error within oob area preceeding ecc bytes... */
                 if (errpos[i] > DOCG4_PAGE_SIZE * 8)
                         change_bit(errpos[i] - DOCG4_PAGE_SIZE * 8,
-                                   (unsigned long *)doc->oob_buf);
+                                   (unsigned long *)nand->oob_poi);
 
                 else    /* error in page data */
                         change_bit(errpos[i], (unsigned long *)buf);
@@ -748,18 +748,12 @@ static int read_page(struct mtd_info *mtd, struct nand_chip *nand,
 
         docg4_read_buf(mtd, buf, DOCG4_PAGE_SIZE); /* read the page data */
 
-        /*
-         * Diskonchips read oob immediately after a page read.  Mtd
-         * infrastructure issues a separate command for reading oob after the
-         * page is read.  So we save the oob bytes in a local buffer and just
-         * copy it if the next command reads oob from the same page.
-         */
-
+        /* this device always reads oob after page data */
         /* first 14 oob bytes read from I/O reg */
-        docg4_read_buf(mtd, doc->oob_buf, 14);
+        docg4_read_buf(mtd, nand->oob_poi, 14);
 
         /* last 2 read from another reg */
-        buf16 = (uint16_t *)(doc->oob_buf + 14);
+        buf16 = (uint16_t *)(nand->oob_poi + 14);
         *buf16 = readw(docptr + DOCG4_MYSTERY_REG);
 
         write_nop(docptr);
@@ -807,21 +801,6 @@ static int docg4_read_oob(struct mtd_info *mtd, struct nand_chip *nand,
 
         dev_dbg(doc->dev, "%s: page %x\n", __func__, page);
 
-        /*
-         * Oob bytes are read as part of a normal page read.  If the previous
-         * nand command was a read of the page whose oob is now being read, just
-         * copy the oob bytes that we saved in a local buffer and avoid a
-         * separate oob read.
-         */
-        if (doc->last_command.command == NAND_CMD_READ0 &&
-            doc->last_command.page == page) {
-                memcpy(nand->oob_poi, doc->oob_buf, 16);
-                return 0;
-        }
-
-        /*
-         * Separate read of oob data only.
-         */
         docg4_command(mtd, NAND_CMD_READ0, nand->ecc.size, page);
 
         writew(DOC_ECCCONF0_READ_MODE | DOCG4_OOB_SIZE, docptr + DOC_ECCCONF0);