brcm63xx: backport upstream solution for SPI message size limits

Backport upstream solution for working around SPI controller maximum
message sizes.

Signed-off-by: Jonas Gorski <jonas.gorski@gmail.com>

1 files changed, 54 insertions, 0 deletions

diff --git a/target/linux/brcm63xx/patches-4.4/000-4.8-09-mtd-spi-nor-add-read-loop.patch b/target/linux/brcm63xx/patches-4.4/000-4.8-09-mtd-spi-nor-add-read-loop.patch
new file mode 100644
index 0000000000..662c73ada9
--- /dev/null
+++ b/target/linux/brcm63xx/patches-4.4/000-4.8-09-mtd-spi-nor-add-read-loop.patch
@@ -0,0 +1,54 @@
+From 26f9bcad29a6c240881bd4efc90f16a9990dd6c2 Mon Sep 17 00:00:00 2001
+From: Michal Suchanek <hramrach@gmail.com>
+Date: Thu, 5 May 2016 17:31:55 -0700
+Subject: [PATCH 09/10] mtd: spi-nor: add read loop
+
+mtdblock and ubi do not handle the situation when read returns less data
+than requested. Loop in spi-nor until buffer is filled or an error is
+returned.
+
+Signed-off-by: Michal Suchanek <hramrach@gmail.com>
+Signed-off-by: Brian Norris <computersforpeace@gmail.com>
+Tested-by Cyrille Pitchen <cyrille.pitchen@atmel.com>
+Acked-by: Michal Suchanek <hramrach@gmail.com>
+Tested-by: Michal Suchanek <hramrach@gmail.com>
+---
+ drivers/mtd/spi-nor/spi-nor.c | 25 +++++++++++++++++++------
+ 1 file changed, 19 insertions(+), 6 deletions(-)
+
+--- a/drivers/mtd/spi-nor/spi-nor.c
++++ b/drivers/mtd/spi-nor/spi-nor.c
+@@ -890,14 +890,27 @@ static int spi_nor_read(struct mtd_info
+ 	if (ret)
+ 		return ret;
+ 
+-	ret = nor->read(nor, from, len, buf);
++	while (len) {
++		ret = nor->read(nor, from, len, buf);
++		if (ret == 0) {
++			/* We shouldn't see 0-length reads */
++			ret = -EIO;
++			goto read_err;
++		}
++		if (ret < 0)
++			goto read_err;
+ 
+-	spi_nor_unlock_and_unprep(nor, SPI_NOR_OPS_READ);
+-	if (ret < 0)
+-		return ret;
++		WARN_ON(ret > len);
++		*retlen += ret;
++		buf += ret;
++		from += ret;
++		len -= ret;
++	}
++	ret = 0;
+ 
+-	*retlen += ret;
+-	return 0;
++read_err:
++	spi_nor_unlock_and_unprep(nor, SPI_NOR_OPS_READ);
++	return ret;
+ }
+ 
+ static int sst_write(struct mtd_info *mtd, loff_t to, size_t len,