Re: EP93xx PIO IDE driver proposal

["João Ramos" <joao.ramos@inov.pt>]

Bartlomiej Zolnierkiewicz escreveu:
> On Friday 08 May 2009 19:28:22 João Ramos wrote:
>   
>>> Yes! :)
>>>
>>> There is still a room for improvement though -- it would be better to fix
>>> IDE core to set PIO0 before probing devices for all host controllers.
>>>
>>> Moreover it seems that doing it this way would allow us to remove ->init_hwif
>>> method from this driver and do all necessary setup in ep93xx_ide_probe()
>>> (this controller is a single port one so theoretically there shouldn't be
>>> a need for having per-port ->init_hwif implementation).
>>>   
>>>       
>> So after all this discussion ;-) , my driver will have no 'init_hwif' 
>> method, and the setup code will be on 'ep93xx_ide_probe', which will 
>> configure entirely the IDE host controller.
>> Moreover, this initial configuration will setup the controller to work 
>> at PIO Mode 0. Later on, the 'set_pio_mode' method will be called and 
>> the controller will configure itself according to the PIO mode reported 
>> by the IDE core.
>>
>> Can I proceed this way?
>>     
>
> Well, yes.  Though I hoped that you would at least give a try to fixing
> IDE core to program PIO0 initially for all host drivers that implement
> ->set_pio_mode method...
>   

Sorry, I didn't noticed your hint... Sure, I can give it a try ;-)
Maybe with a little help, but I can try. You mean, when the host driver 
is registered (ide_host_register, or ide_host_add that later calls 
ide_host_register), maybe in the 'ide_init_port' method (sorry, I need 
some guidance here...) check if the 'set_pio_mode' method is 
implemented, and after initializing each port (d->init_hwif(hwif)) 
default it to PIO Mode 0, calling set_pio_mode method.

Is this correct? Sorry, has I stated earlier, I'm wasn't familiar with 
the IDE susbsystem untill I wrote this patch; but I'm willing to 
contribute in any way I can, so please, bear with me on this :-) .

>   
>>>   
>>>       
>>>> There's just only one issue; normally, I would setup the specific 
>>>> timings (t0, t1, t2, t2i, etc) in the 'pio_set_mode' hook. However, if 
>>>> you look further in the driver, those timings aren't defined through a 
>>>> memory controller but instead manually enforced by 'ndelay' calls (arghhh).
>>>> This means that in my low-level procedures for reading and writing, I 
>>>> need to have access to the timings (or the struct ide_timing) 
>>>> corresponding to the PIO mode selected, in order to use the correct delays.
>>>>
>>>> My question is: which is the best way to accomplish this? Declaring a 
>>>> global struct ide_timing variable pointer that always holds the correct 
>>>> ide_timing struct to the selected PIO mode? Or should I always check (in 
>>>> some manner) what is the current PIO mode and then select the adequate 
>>>> delays?
>>>>     
>>>>         
>>> I think that the setting variable pointer in ->set_pio_mode method would
>>> work best.  Seems like the existing drive_data field of ide_drive_t is well
>>> suited for this purpose (however it may be worth to convert it to 'void *'
>>> type while we are it).
>>>   
>>>       
>> Did you mean 'drive_data' field, or 'driver_data' field?
>> 'drive_data' field is an unsigned int value; I guess you meant 
>> 'driver_data' field as it is a (void *) field, so I can define it as a 
>> pointer to the correct 'struct ide_timing'.
>>     
>
> That is why I hinted that you may need to convert 'drive_data' to
> 'void *' type first.  You may also try to use 'driver_data' instead
> but you will discover rather quickly that you shouldn't do this... ;)
>
> 'driver_data' is for use by IDE core and IDE device drivers.
>
> 'drive_data' is for use by IDE host drivers.
>   

And this conversion is made by my driver code, or should I fix directly 
in the ide_drive_t structure?

Regards,
João Ramos

> Thanks,
> Bart
>
>   


-- 
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    João Ramos        <joao.ramos@inov.pt>

    INOV INESC Inovação - ESTG Leiria
    Escola Superior de Tecnologia e Gestão de Leiria
    Edíficio C1, Campus 2
    Morro do Lena, Alto do Vieiro
    Leiria
    2411-901 Leiria
    Portugal

    Tel: +351244843424
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