Re: [PATCH 2/3] ide: add at91_ide driver

[Sergei Shtylyov <sshtylyov@ru.mvista.com>]

Hello, I wrote:

>>>>>>> +void at91_ide_tf_load(ide_drive_t *drive, ide_task_t *task)
>>>>>>> +{
>>>>>>> +    ide_hwif_t *hwif = drive->hwif;
>>>>>>> +    struct ide_io_ports *io_ports = &hwif->io_ports;
>>>>>>> +    struct ide_taskfile *tf = &task->tf;
>>>>>>> +    u8 HIHI = (task->tf_flags & IDE_TFLAG_LBA48) ? 0xE0 : 0xEF;
>>>>>>> +
>>>>>>> +    if (task->tf_flags & IDE_TFLAG_FLAGGED)
>>>>>>> +        HIHI = 0xFF;
>>>>>>> +
>>>>>>> +    if (task->tf_flags & IDE_TFLAG_OUT_DATA) {
>>>>>>>                   
>>>>>>    Sigh. Bart, couldn't we drop that stupid flag? I bet nobody 
>>>>>> ever used it.
>>>>>>             
>>>>> It is there for HDIO_DRIVE_TASKFILE ioctl and I prefer not to 
>>>>> break it.
>>>>>
>>>>> Just add ->{read,write}_data methods for IDE_TFLAG_{IN,OUT}_DATA 
>>>>> to struct
>>>>> ide_tp_ops -- it should also help some other host drivers like 
>>>>> tx493*.
>>>>>         
>>>>   That would be extremely senseless activity sicne I believe this 
>>>> flag is totally useless. I have better thing to do. :-)
>>>>     
>>>
>>> I would love to remove this flag but it is used by user-space exposed
>>> interface 
>>
>>   I know that...
>>
>>> (which was used by few drive vendors for their diagnostics
>>> tools -- doesn't matter whether internal or external) so you should put
>>> some technical arguments behind its removal (you know many of low-level
>>> technical details better than me so I may be missing something which is
>>> obvious to you).
>>>   
>>
>>   Well, the vendors can do strange things, of course...
>>   However, accessing the data register is certainly not a part of any 
>> ATA/PI defined command's inputs/outputs (the corresponding tables 
>> just don't have this register). I suspect that this flag was added 
>> just "for completeness".
>>
>>> OTOH while ->{read,write}_data approach would result in something like
>>> ~50 extra LOC (or even less with be_tp_ops) compared to removal it is
>>> completely safe and we don't need to spend a single second wondering
>>> about potential breakage 
>>
>>   Go for it. ;-)
>
>   I think I have a better idea than creating another (useless) couple 
> of "transport" methods. Why not (ab)use the exisitng 
> {in|out}put_data() methods instead? :-)

   Besides, those methods are clearly subject to some size 
optimization... I'll cook up a patch while I'm at it. :-)

MBR, Sergei