re: mmc: Driver for CB710/720 memory card reader (MMC part)

[Dan Carpenter <dan.carpenter@oracle.com>]

Hello Michał Mirosław,

The patch 5f5bac8272be: "mmc: Driver for CB710/720 memory card reader
(MMC part)" from May 22, 2009, leads to the following static checker
warning:

	drivers/mmc/host/cb710-mmc.c:579 cb710_mmc_set_ios()
	warn: 'err' can be either negative or positive

drivers/mmc/host/cb710-mmc.c
   112  
   113  static int cb710_check_event(struct cb710_slot *slot, u8 what)
   114  {
   115          u16 status;
   116  
   117          status = cb710_read_port_16(slot, CB710_MMC_STATUS_PORT);
   118  
   119          if (status & CB710_MMC_S0_FIFO_UNDERFLOW) {
   120                  /* it is just a guess, so log it */
   121                  dev_dbg(cb710_slot_dev(slot),
   122                          "CHECK : ignoring bit 6 in status %04X\n", status);
   123                  cb710_write_port_8(slot, CB710_MMC_STATUS0_PORT,
   124                          CB710_MMC_S0_FIFO_UNDERFLOW);
   125                  status &= ~CB710_MMC_S0_FIFO_UNDERFLOW;
   126          }
   127  
   128          if (status & CB710_MMC_STATUS_ERROR_EVENTS) {
   129                  dev_dbg(cb710_slot_dev(slot),
   130                          "CHECK : returning EIO on status %04X\n", status);
   131                  cb710_write_port_8(slot, CB710_MMC_STATUS0_PORT, status & 0xFF);
   132                  cb710_write_port_8(slot, CB710_MMC_STATUS1_PORT,
   133                          CB710_MMC_S1_RESET);
   134                  return -EIO;
   135          }
   136  
   137          /* 'what' is a bit in MMC_STATUS1 */
   138          if ((status >> 8) & what) {
   139                  cb710_write_port_8(slot, CB710_MMC_STATUS1_PORT, what);
   140                  return 1;

There are two callers to this function.  It appears to me that one
expects zero on error and one expects non-zero on error.  It is
confusing and there are no comments explaining the return codes.

   141          }
   142  
   143          return 0;
   144  }

regards,
dan carpenter