kernel: Move an upstreamed patch under backports

This CFI patch was accepted upstream for 5.13. Move it away from under
ath79 and place under backports to be removed in due time.

Signed-off-by: Mauri Sandberg <sandberg@mailfence.com>

1 files changed, 54 insertions, 0 deletions

diff --git a/target/linux/generic/backport-5.4/408-v5.13-mtd-cfi_cmdset_0002-Disable-buffered-writes-for-AMD.patch b/target/linux/generic/backport-5.4/408-v5.13-mtd-cfi_cmdset_0002-Disable-buffered-writes-for-AMD.patch
new file mode 100644
index 0000000000..3af641e62e
--- /dev/null
+++ b/target/linux/generic/backport-5.4/408-v5.13-mtd-cfi_cmdset_0002-Disable-buffered-writes-for-AMD.patch
@@ -0,0 +1,54 @@
+From 7e4404113686868858a34210c28ae122e967aa64 Mon Sep 17 00:00:00 2001
+From: Mauri Sandberg <sandberg@mailfence.com>
+Date: Tue, 9 Mar 2021 19:48:59 +0200
+Subject: [PATCH] mtd: cfi_cmdset_0002: Disable buffered writes for AMD chip
+ 0x2201
+
+Buffer writes do not work with AMD chip 0x2201. The chip in question
+is a AMD/Spansion/Cypress Semiconductor S29GL256N and datasheet [1]
+talks about writing buffers being possible. While waiting for a neater
+solution resort to writing word-sized chunks only.
+
+Without the patch kernel logs will be flooded with entries like below:
+
+jffs2_scan_eraseblock(): End of filesystem marker found at 0x0
+jffs2_build_filesystem(): unlocking the mtd device...
+done.
+jffs2_build_filesystem(): erasing all blocks after the end marker...
+MTD do_write_buffer_wait(): software timeout, address:0x01ec000a.
+jffs2: Write clean marker to block at 0x01920000 failed: -5
+MTD do_write_buffer_wait(): software timeout, address:0x01e2000a.
+jffs2: Write clean marker to block at 0x01880000 failed: -5
+MTD do_write_buffer_wait(): software timeout, address:0x01e0000a.
+jffs2: Write clean marker to block at 0x01860000 failed: -5
+MTD do_write_buffer_wait(): software timeout, address:0x01dc000a.
+jffs2: Write clean marker to block at 0x01820000 failed: -5
+MTD do_write_buffer_wait(): software timeout, address:0x01da000a.
+jffs2: Write clean marker to block at 0x01800000 failed: -5
+...
+
+Tested on a Buffalo wzr-hp-g300nh running kernel 5.10.16.
+
+[1] https://www.cypress.com/file/219941/download
+or  https://datasheetspdf.com/pdf-file/565708/SPANSION/S29GL256N/1
+
+Signed-off-by: Mauri Sandberg <sandberg@mailfence.com>
+Signed-off-by: Vignesh Raghavendra <vigneshr@ti.com>
+Link: https://lore.kernel.org/r/20210309174859.362060-1-sandberg@mailfence.com
+---
+ drivers/mtd/chips/cfi_cmdset_0002.c | 4 ++++
+ 1 file changed, 4 insertions(+)
+
+--- a/drivers/mtd/chips/cfi_cmdset_0002.c
++++ b/drivers/mtd/chips/cfi_cmdset_0002.c
+@@ -272,6 +272,10 @@ static void fixup_use_write_buffers(stru
+ {
+ 	struct map_info *map = mtd->priv;
+ 	struct cfi_private *cfi = map->fldrv_priv;
++
++	if (cfi->mfr == CFI_MFR_AMD && cfi->id == 0x2201)
++		return;
++
+ 	if (cfi->cfiq->BufWriteTimeoutTyp) {
+ 		pr_debug("Using buffer write method\n");
+ 		mtd->_write = cfi_amdstd_write_buffers;