On Wed, Aug 12, 2015 at 02:00:51PM +0300, Dan Carpenter wrote:
> 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.
Hah. The code is correct, though I admit that it's not obvious at first glance.
Feel free to send a patch. :-)
Call inside cb710_wait_for_event() is spinning while there's no error and the
requested event was not signalled. The call from cb710_mmc_powerup() is there
only to check for error condition and since it gets 0 in 'what' it will never
return 1 (>0).
Best Regards,
Michał Mirosław
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