Mark Lord wrote:
> Tejun Heo wrote:
>> ..
>> Then, PACKET_IDENTIFY after configuring transfer mode fails with
>> -ENOENT. Meaning it saw (status & (ATA_BUSY|ATA_DRQ|ATA_ERR|ATA_DF)) ==
>> 0 in HSM_ST.
> ..
>> So, PATA gurus, can you bless us with enlightenment? :-)
>
> Heh.. guaranteeing detection of all the strange implementations out there
> is part black magic.
>
> But the simple thing to do here is, just for fun, hack the code
> to do the infamous 50 millisecond hard wait before issuing the
> PACKET_IDENTIFY.
> If that fixes it, then it's just a matter of tuning to discover the real
> amount of delay required, and a nicer way of doing the delay.
Okay.
> Also, zero out the features register before issuing PACKET_IDENTIFY,
> if the code isn't already doing that.
Okay.
> After the drive asserts BUSY, and later deasserts BUSY,
> there might be a slight delay before the drive asserts DRQ.
> So, it is possible for the status to read zeros in the important bits.
>
> My suggestion is to wait up to the infamous 50 milliseconds again here,
> if needed.
Okay, the attached patch does what Mark suggested. Art, can you please
give it a shot and report dmesg? My thanks for sticking around till now.
--
tejun
diff --git a/drivers/ata/libata-core.c b/drivers/ata/libata-core.c
index 667acd2..4c81433 100644
--- a/drivers/ata/libata-core.c
+++ b/drivers/ata/libata-core.c
@@ -1478,7 +1478,8 @@ int ata_dev_read_id(struct ata_device *dev, unsigned int *p_class,
}
tf.protocol = ATA_PROT_PIO;
- tf.flags |= ATA_TFLAG_POLLING; /* for polling presence detection */
+ /* POLLING for polling detection, ISADDR|DEVICE to clear TF */
+ tf.flags |= ATA_TFLAG_POLLING | ATA_TFLAG_ISADDR | ATA_TFLAG_DEVICE;
err_mask = ata_exec_internal(dev, &tf, NULL, DMA_FROM_DEVICE,
id, sizeof(id[0]) * ATA_ID_WORDS);
@@ -4477,6 +4478,18 @@ fsm_start:
goto fsm_start;
} else {
+ unsigned long timeout = jiffies + msecs_to_jiffies(50);
+
+ while (time_before(jiffies, timeout)) {
+ if (status & ATA_DRQ)
+ break;
+ ata_dev_printk(qc->dev, KERN_INFO,
+ "XXX: waiting for DRQ, status=0x%x\n",
+ status);
+ msleep(10);
+ status = ata_chk_status(ap);
+ }
+
/* ATA PIO protocol */
if (unlikely((status & ATA_DRQ) == 0)) {
/* handle BSY=0, DRQ=0 as error */
