Messages in this thread | | | Date | Wed, 04 Mar 2009 18:43:45 +0300 | From | Sergei Shtylyov <> | Subject | Re: [PATCH 13/18] ide: use ->tf_load in SELECT_DRIVE() |
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Hello, I wrote:
>>>>>>>> There should be no functional changes caused by this patch. >>>>>>>> Signed-off-by: Bartlomiej Zolnierkiewicz <bzolnier@gmail.com> >>>>>>>> Index: b/drivers/ide/ide-iops.c >>>>>>>> =================================================================== >>>>>>>> --- a/drivers/ide/ide-iops.c >>>>>>>> +++ b/drivers/ide/ide-iops.c >>>>>>>> @@ -88,11 +88,15 @@ void SELECT_DRIVE (ide_drive_t *drive) >>>>>>>> { >>>>>>>> ide_hwif_t *hwif = drive->hwif; >>>>>>>> const struct ide_port_ops *port_ops = hwif->port_ops; >>>>>>>> + ide_task_t task;
>>>>>>>> if (port_ops && port_ops->selectproc) >>>>>>>> port_ops->selectproc(drive); >>>>>>>> >>>>>>>> - hwif->OUTB(drive->select.all, hwif->io_ports.device_addr); >>>>>>>> + memset(&task, 0, sizeof(task)); >>>>>>>> + task.tf_flags = IDE_TFLAG_OUT_DEVICE; >>>>>>>> + >>>>>>>> + drive->hwif->tf_load(drive, &task);
>>>>>>> This actually doesn't seem like a bright idea to me, >>>>>>> considering that this gets called when starting every request. >>>>>>> How will you look at me adding the transport method for writing >>>>>>> this register? :-)
>>>> Please check profiles first -- it might not be worth it. [1]
>>>>>> Convert SELECT_DRIVE() to use ->tf_load instead of ->OUTB.
>>>>>> OTOH, adding such a "backdoor" to the taskfile doesn't seem very >>>>>> consistent... well, I'm not excited about the whole idea >>>>>> conversion to tf_{load|read}() -- it's not clear what exactly this >>>>>> bought us.
>>>> This was explained some months ago already, so just to recall -- it was >>>> a part of a bigger work removing duplicated code and allowing >>>> abstraction >>>> of the ATA logic.
>>>> Anyway this is not set in a stone so if you have proposal of a better >>>> approach please come forward with it.
>>> Er... I think that the previous IN()/OUT() methods were better. >>> Note that we ended up using the local version of them in the dafault >>> ide_tf_{load}read}() anyway -- as Alan has pointed out it might be worth
>> During ide_tf_{load,read}() addition I was a bit too optimistic about >> the possibility of the quick io{read,write}* conversion later...
>>> splitting those into I/O and memory space versions... although given >>> general slowness of the I/O accesses, this is probably not going to >>> win much speed-wise.
>> Maybe it would be worth to add ->tf_{inb,outb} to struct ide_tp_ops >> and convert default tp_ops to use them... OTOH we should reinvestigate >> the io{read,write}*() way first (maybe things have improved there)...
> Yes, let's not be hasty here...
What I certainly don't like is how tf_load/read() handle LBA48: there's much of the code duplication going on. I'll think what can be done about it but it may not be easy to tackle... it looks like 'struct ide_taskfile' needs to be reorganized to include 2 6-byte sub-structures.
>> Thanks, >> Bart
MBR, Sergei
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