target/linux/generic/pending-4.14/450-mtd-m25p80-allow-fallback-from-spi_flash_read-to-reg.patch

   1 From: Felix Fietkau <nbd@nbd.name>
   2 Date: Fri, 23 Feb 2018 17:12:16 +0100
   3 Subject: [PATCH] mtd: m25p80: allow fallback from spi_flash_read to regular
   4  SPI transfer
   5
   6 Some flash controllers, e.g. on the ath79 platform can support a fast
   7 flash read via memory mapping, but only if the flash chip is in
   8 3-byte address mode.
   9
  10 Since spi_flash_read_supported does not have access to the same data as
  11 spi_flash_read, the driver can't detect an unsupported call until m25p80
  12 has decided to use spi_flash_read.
  13
  14 Allow the driver to indicate a fallback to a regular SPI transfer by
  15 returning -EOPNOTSUPP
  16
  17 Signed-off-by: Felix Fietkau <nbd@nbd.name>
  18 ---
  19
  20 --- a/drivers/mtd/devices/m25p80.c
  21 +++ b/drivers/mtd/devices/m25p80.c
  22 @@ -170,9 +170,11 @@ static ssize_t m25p80_read(struct spi_no
  23                 msg.data_nbits = data_nbits;
  24
  25                 ret = spi_flash_read(spi, &msg);
  26 -               if (ret < 0)
  27 -                       return ret;
  28 -               return msg.retlen;
  29 +               if (ret != -EOPNOTSUPP) {
  30 +                       if (ret < 0)
  31 +                               return ret;
  32 +                       return msg.retlen;
  33 +               }
  34         }
  35
  36         spi_message_init(&m);