[PATCH] mtd: chips: AMD chip 0x2201 - write words not buffers

[Mauri Sandberg]

CFI flash memory driver cmdset_0002 uses buffers for write operations.
That does not work with AMD chip with id 0x2201 and we must resort to
writing word sized chunks only.

This patch creates fixup mechanism that renders a chip to use word sized
write operation and adds that as the last item in a fixup table, shadowing
the entry that causes use of buffer writes.

Without the patch kernel logs will be flooded with entries like below:

MTD do_erase_oneblock(): ERASE 0x01fa0000
MTD do_write_buffer(): WRITE 0x01fa0000(0x00001985)
MTD do_erase_oneblock(): ERASE 0x01f80000
MTD do_write_buffer(): WRITE 0x01f80000(0x00001985)
MTD do_write_buffer_wait(): software timeout, address:0x01f8000a.
jffs2: Write clean marker to block at 0x01a60000 failed: -5
MTD do_erase_oneblock(): ERASE 0x01f60000
MTD do_write_buffer(): WRITE 0x01f60000(0x00001985)
MTD do_write_buffer_wait(): software timeout, address:0x01f6000a.
jffs2: Write clean marker to block at 0x01a40000 failed: -5

Signed-off-by: Mauri Sandberg <sandberg at mailfence.com>
---
 drivers/mtd/chips/cfi_cmdset_0002.c | 8 ++++++++
 1 file changed, 8 insertions(+)

diff --git a/drivers/mtd/chips/cfi_cmdset_0002.c b/drivers/mtd/chips/cfi_cmdset_0002.c
index a1f3e1031c3d..b8b564342062 100644
--- a/drivers/mtd/chips/cfi_cmdset_0002.c
+++ b/drivers/mtd/chips/cfi_cmdset_0002.c
@@ -279,6 +279,12 @@ static void fixup_use_write_buffers(struct mtd_info *mtd)
 }
 #endif /* !FORCE_WORD_WRITE */
 
+static void fixup_use_write_words(struct mtd_info *mtd)
+{
+	pr_debug("Using word write method\n");
+	mtd->_write = cfi_amdstd_write_words;
+}
+
 /* Atmel chips don't use the same PRI format as AMD chips */
 static void fixup_convert_atmel_pri(struct mtd_info *mtd)
 {
@@ -470,8 +476,10 @@ static struct cfi_fixup cfi_fixup_table[] = {
 #if !FORCE_WORD_WRITE
 	{ CFI_MFR_ANY, CFI_ID_ANY, fixup_use_write_buffers },
 #endif
+	{ CFI_MFR_AMD, 0x2201, fixup_use_write_words },
 	{ 0, 0, NULL }
 };
+
 static struct cfi_fixup jedec_fixup_table[] = {
 	{ CFI_MFR_SST, SST49LF004B, fixup_use_fwh_lock },
 	{ CFI_MFR_SST, SST49LF040B, fixup_use_fwh_lock },
-- 
2.25.1