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mg_disk: fix reading invalid status when use polling driver

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When using polling driver, little delay is required to access
status register. Without this, host might read invalid status.

Signed-off-by: unsik Kim <donari75@gmail.com>
Signed-off-by: Jens Axboe <jens.axboe@oracle.com>
This commit is contained in:
unsik Kim 2009-07-28 08:52:07 +02:00 committed by Jens Axboe
parent 48f5690d45
commit eb32baec15
1 changed files with 10 additions and 0 deletions
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10
drivers/block/mg_disk.c
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@ -219,6 +219,16 @@ static unsigned int mg_wait(struct mg_host *host, u32 expect, u32 msec)
host->error = MG_ERR_NONE;
expire = jiffies + msecs_to_jiffies(msec);
/* These 2 times dummy status read prevents reading invalid
* status. A very little time (3 times of mflash operating clk)
* is required for busy bit is set. Use dummy read instead of
* busy wait, because mflash's PLL is machine dependent.
*/
if (prv_data->use_polling) {
status = inb((unsigned long)host->dev_base + MG_REG_STATUS);
status = inb((unsigned long)host->dev_base + MG_REG_STATUS);
}
status = inb((unsigned long)host->dev_base + MG_REG_STATUS);
do {