From eb32baec15c38ae6f06cb898a9f791578c5f8c79 Mon Sep 17 00:00:00 2001 From: unsik Kim Date: Tue, 28 Jul 2009 08:52:07 +0200 Subject: mg_disk: fix reading invalid status when use polling driver When using polling driver, little delay is required to access status register. Without this, host might read invalid status. Signed-off-by: unsik Kim Signed-off-by: Jens Axboe --- drivers/block/mg_disk.c | 10 ++++++++++ 1 file changed, 10 insertions(+) (limited to 'drivers') diff --git a/drivers/block/mg_disk.c b/drivers/block/mg_disk.c index 5b120eab2baa..6440d5945414 100644 --- a/drivers/block/mg_disk.c +++ b/drivers/block/mg_disk.c @@ -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 { -- cgit v1.2.2