Re: [PATCH 3/9] libata: implement per-dev xfermask

[Tejun Heo <htejun@gmail.com>]

Alan Cox wrote:
> Ar Sad, 2006-08-05 am 06:01 +0900, ysgrifennodd Tejun Heo:
>> +	/* Use the lowest common PIO mode to avoid violating device
>> +	 * selection timing.
>> +	 */
>> +	for (i = 0; i < ATA_MAX_DEVICES; i++) {
>> +		struct ata_device *d = &ap->device[i];
>> +		if (!ata_dev_absent(d))
>> +			xfer_mask &= ata_pack_xfermask(d->pio_mask,
>> +						       UINT_MAX, UINT_MAX);
>>  	}
> 
> We should not do this. Many of the controllers are smart enough to get
> it right and those which do not implement this logic internally and
> correctly by merging the relevant fields in the ata timing structure.

[Cc'ing Mark Lord for upstream PATA drivers]

I see.  I have a question though.  ATM, there are a few drives in the 
current #upstream which deal with PATA devices (ata_piix, pdc_adma and 
sata_promise).  Will they all act correctly without the above logic?  If 
so, I'll drop the above part and regenerate the tree.  If not, it can 
stay till those drivers are patched.

Thanks.

-- 
tejun