target/linux/bcm53xx/patches-4.4/406-mtd-m25p80-use-single-SPI-message-for-writing-data.patch

   1 From: =?UTF-8?q?Rafa=C5=82=20Mi=C5=82ecki?= <zajec5@gmail.com>
   2 Subject: [PATCH] mtd: m25p80: use single SPI message for writing data
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   6
   7 On all 3 tested Northstar devices with following flash memories:
   8 mx25l6405d (8192 Kbytes)
   9 mx25l12805d (16384 Kbytes)
  10 mx25l25635e (32768 Kbytes)
  11 I noticed writing to be broken. Not a single bit was changed leaving all
  12 bytes set to 0xff.
  13
  14 This is most likely some problem related to the SPI controller or its
  15 driver. Using a single SPI message seems to workaround this. Of course
  16 it's not perfect solution as copying whole data into a new buffer makes
  17 writing slower.
  18
  19 Signed-off-by: Rafał Miłecki <zajec5@gmail.com>
  20 ---
  21
  22 --- a/drivers/mtd/devices/m25p80.c
  23 +++ b/drivers/mtd/devices/m25p80.c
  24 @@ -78,6 +78,7 @@ static void m25p80_write(struct spi_nor
  25  {
  26         struct m25p *flash = nor->priv;
  27         struct spi_device *spi = flash->spi;
  28 +       u8 *command = kzalloc(MAX_CMD_SIZE + len, GFP_KERNEL);
  29         struct spi_transfer t[2] = {};
  30         struct spi_message m;
  31         int cmd_sz = m25p_cmdsz(nor);
  32 @@ -87,20 +88,19 @@ static void m25p80_write(struct spi_nor
  33         if (nor->program_opcode == SPINOR_OP_AAI_WP && nor->sst_write_second)
  34                 cmd_sz = 1;
  35
  36 -       flash->command[0] = nor->program_opcode;
  37 -       m25p_addr2cmd(nor, to, flash->command);
  38 +       command[0] = nor->program_opcode;
  39 +       m25p_addr2cmd(nor, to, command);
  40 +       memcpy(&command[cmd_sz], buf, len);
  41
  42 -       t[0].tx_buf = flash->command;
  43 -       t[0].len = cmd_sz;
  44 +       t[0].tx_buf = command;
  45 +       t[0].len = cmd_sz + len;
  46         spi_message_add_tail(&t[0], &m);
  47
  48 -       t[1].tx_buf = buf;
  49 -       t[1].len = len;
  50 -       spi_message_add_tail(&t[1], &m);
  51 -
  52         spi_sync(spi, &m);
  53
  54         *retlen += m.actual_length - cmd_sz;
  55 +
  56 +       kfree(command);
  57  }
  58
  59  static inline unsigned int m25p80_rx_nbits(struct spi_nor *nor)