bcm53xx: add m25p80 workaround for SPI flash writing problems

Signed-off-by: Rafał Miłecki <zajec5@gmail.com>
SVN-Revision: 49264

diff --git a/target/linux/bcm53xx/patches-4.4/406-mtd-m25p80-use-single-SPI-message-for-writing-data.patch b/target/linux/bcm53xx/patches-4.4/406-mtd-m25p80-use-single-SPI-message-for-writing-data.patch
new file mode 100644 (file)
index 0000000..0e0cce2
--- /dev/null
+++ b/target/linux/bcm53xx/patches-4.4/406-mtd-m25p80-use-single-SPI-message-for-writing-data.patch
@@ -0,0 +1,62 @@
+From: =?UTF-8?q?Rafa=C5=82=20Mi=C5=82ecki?= <zajec5@gmail.com>
+Subject: [PATCH] mtd: m25p80: use single SPI message for writing data
+MIME-Version: 1.0
+Content-Type: text/plain; charset=UTF-8
+Content-Transfer-Encoding: 8bit
+
+On all 3 tested Northstar devices with following flash memories:
+mx25l6405d (8192 Kbytes)
+mx25l12805d (16384 Kbytes)
+mx25l25635e (32768 Kbytes)
+I noticed writing to be broken. Not a single bit was changed leaving all
+bytes set to 0xff.
+
+This is most likely some problem related to the SPI controller or its
+driver. Using a single SPI message seems to workaround this. Of course
+it's not perfect solution as copying whole data into a new buffer makes
+writing slower.
+
+Signed-off-by: Rafał Miłecki <zajec5@gmail.com>
+---
+
+--- a/drivers/mtd/devices/m25p80.c
++++ b/drivers/mtd/devices/m25p80.c
+@@ -78,29 +78,30 @@ static void m25p80_write(struct spi_nor *nor, loff_t to, size_t len,
+ {
+       struct m25p *flash = nor->priv;
+       struct spi_device *spi = flash->spi;
++      u8 *command = kzalloc(MAX_CMD_SIZE + len, GFP_KERNEL);
+       struct spi_transfer t[2] = {};
+       struct spi_message m;
+       int cmd_sz = m25p_cmdsz(nor);
++      int i;
+ 
+       spi_message_init(&m);
+ 
+       if (nor->program_opcode == SPINOR_OP_AAI_WP && nor->sst_write_second)
+               cmd_sz = 1;
+ 
+-      flash->command[0] = nor->program_opcode;
+-      m25p_addr2cmd(nor, to, flash->command);
++      command[0] = nor->program_opcode;
++      m25p_addr2cmd(nor, to, command);
++      memcpy(&command[cmd_sz], buf, len);
+ 
+-      t[0].tx_buf = flash->command;
+-      t[0].len = cmd_sz;
++      t[0].tx_buf = command;
++      t[0].len = cmd_sz + len;
+       spi_message_add_tail(&t[0], &m);
+ 
+-      t[1].tx_buf = buf;
+-      t[1].len = len;
+-      spi_message_add_tail(&t[1], &m);
+-
+       spi_sync(spi, &m);
+ 
+       *retlen += m.actual_length - cmd_sz;
++
++      kfree(command);
+ }
+ 
+ static inline unsigned int m25p80_rx_nbits(struct spi_nor *nor)