ATA/IDE disk access using PIO and interrupt

[Eugeny S. Mints]

Hello Yan,

Yan Luo wrote:
> Sorry, I mean
> 
> "I was trying to understand how interrupt works for the PIO as it is 
> said in the document (ata.t) that PIO is supported by both polling and 
> INTERRUPT."
> 
> ----- Original Message ----- From: "Yan Luo" <yan_luo at uml.edu>
> To: <rtems-users at rtems.com>
> Sent: Thursday, May 25, 2006 2:25 PM
> Subject: ATA/IDE disk access using PIO and interrupt
> 
> 
>> Hello All,
>>
>> I was trying to understand how interrupt works for the PIO as it is 
>> said in the document (ata.t) that PIO is supported by both polling and 
>> PIO.
>>
>> I don't see the IDE_Controller_Table[ctrl_minor].int_driven set to 
>> TRUE anywhere in the source tree. That means the interrupt driven PIO 
>> is NOT enabled at all.
you mentioned you are on 4.6.2 but you could check 4.6.99.3 and take a 
look at powerpc/gen5200 bsp. ide/idecfg.c in this bsp has 'int_driven' 
flag set under 'ifdef ATA_USE_INT'. Since ATA_USE_INT is undefined in 
bsp.h for this bsp I have no idea whether anybody gives this a try but I 
guess Thomas could shed a light on this :)

But the bottom line is that since all the code needed to support 
interrupt driven PIO is implemented in a generic way in ata.c the only 
thing an ide controller driver has to export to ata driver is a proper 
interrupt vector number (acompanied with int_driven flag set).
>>
>> I tried to set it as true in ide_controller_initialize() 
ide controller configuration currently is designed as a compile time 
option, is represented as a structure of type 
'ide_controller_bsp_table_t' (IDE_Controller_Table[] is array of 
'ide_controller_bsp_table_t' structures, one per ide controller on your 
target) and usually locates in ide/idecfg.c under 'your bsp' (for ex 
c/src/lib/libbsp/i386/pc386) directory.
Therefore you just need to set 'int_driven' flag properly among others 
initialization values for the structure.
 >>
>>in ide_ctrl.c. That caused the RTEMS hang.
You didn't specify what bsp you are on. IIUC there are 3 bsp in 4.6.99.3 
which contain ide controller driver: pc386, powerpc/mbx8xx and 
powerpc/gen5200. There is no powerpc/gen5200 ide support in 4.6.2.

My guess would be you are on i386. If so, you need to initialize int_vec 
field of ide_controller_bsp_table_t structure in 
lib/libbsp/i386/pc386/ide/idecfg.c with a proper interrupt number as 
well as set up int_driven flag to TRUE.

Hope this helps,
	Eugeny
>>
>> How the interrupt for PIO is enabled?
>>
>> My test is on RTEMS 4.6.2 with fileio example application.
>>
>> Thanks,
>> Yan
>>
>>
> 
>