On Mon, Oct 14, 2013 at 02:58:19PM +0200, Lukasz Dorau wrote: > If EM Transmit bit is busy during init ata_msleep() is called. > It is wrong - msleep() should be used instead of ata_msleep(), > because if EM Transmit bit is busy for one port, it will be busy > for all other ports too, so using ata_msleep() causes wasting > tries for another ports. > > The most common scenario looks like that now > (six ports try to transmit a LED meaasege): > - port #0 tries for the 1st time and succeeds > - ports #1-5 try for the 1st time and sleeps > - port #1 tries for the 2nd time and succeeds > - ports #2-5 try for the 2nd time and sleeps > - port #2 tries for the 3rd time and succeeds > - ports #3-5 try for the 3rd time and sleeps > - port #3 tries for the 4th time and succeeds > - ports #4-5 try for the 4th time and sleeps > - port #4 tries for the 5th time and succeeds > - port #5 tries for the 5th time and sleeps > At this moment port #5 wasted all its five tries and failed to initialize. > Because there are only 5 (EM_MAX_RETRY) tries available usually only five > ports > succeed to initialize. The sixth port and next ones usually will fail. > > If msleep() is used instead of ata_msleep() the first port succeeds to > initialize > in the first try and next ones usually succeed to initialize in the second > try.
Ah, interesting. > Signed-off-by: Lukasz Dorau <lukasz.do...@intel.com> > --- > drivers/ata/libahci.c | 2 +- > 1 file changed, 1 insertion(+), 1 deletion(-) > > diff --git a/drivers/ata/libahci.c b/drivers/ata/libahci.c > index acfd0f7..cf38692 100644 > --- a/drivers/ata/libahci.c > +++ b/drivers/ata/libahci.c > @@ -779,7 +779,7 @@ static void ahci_start_port(struct ata_port *ap) > emp->led_state, > 4); > if (rc == -EBUSY) > - ata_msleep(ap, 1); > + msleep(1); This is so unobvious. Can you please add a comment explaining what's going on? Thanks. -- tejun -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
