Anyone can help me about do_write_buffer at cfi_cmdset_0002

[Qi Zhang]

Hello:

    In functions
    do_write_buffer @ drivers/mtd/chips/cfi_cmdset_0002.c.
    ...
    map_write(map, CMD(0x29), cmd_adr);
    /* send buffer program command */
    chip->state = FL_WRITING;
    /* change chip state */
    INVALIDATE_CACHE_UDELAY(map, chip, adr, map_bankwidth(map),
                                                   chip->word_write_time);
    /* why word_write_time? */
    ...

    Struct flchip already have "buffer_write_time",
    seems it should replace the "word_write_time".
    Both of thems come from the cfi_ident's
    "WordWriteTimeoutTyp" and "BufWriteTimeoutTyp",
    which indicate the real flash performance on word program
    and buffer program and usually they are quite different.

    Further more, the cfi_ident also have
    "WordWriteTimeoutMax", "BufWriteTimeoutMax",
    but the real implementation igore them as below

    ......
    unsigned long uWriteTimeout = ( HZ / 1000 ) + 1;
    ....
    INVALIDATE_CACHE_UDELAY(map, chip, adr, map_bankwidth(map),
                                                   chip->word_write_time);
    timeo = jiffies + uWriteTimeout;
    for (;;) {
       ......
       if (time_after(jiffies, timeo) && !chip_ready(map, adr))
       break;
       ......
   }

   The max time out will be "word_write_time" + "uWriteTimeOut"

   Let's look at Intel M29EW flash's CFI spec.

   WordWriteTimeoutTyp : 512us
   BufWriteTimeoutTyp    : 1024us
   WordWriteTimeoutMax: 1024us
   BufWriteTimeoutMax:    4096us

   for HZ = 100, that will be ok since 1 tick 10ms
   But for HZ = 1000, we got only 2.5ms ( 512us + 2 ticks),
   and 3ms (1024us + 2 ticks)
  (when replaced word_write_time with buf_write_time).
   Both are not met 4096us spec.

   Does anybody can help on that?

Thanks
Zhang Qi