Re: [PATCH 1/2] ide: Add tx4939ide driver

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

Hello.

Atsushi Nemoto wrote:

>>>>>+		/*
>>>>>+		 * If only one of XFERINT and HOST was asserted, mask
>>>>>+		 * this interrupt and wait for an another one.  Note

>>>>  This comment somewhat contradicts the code which returns 1 if only 
>>>>HOST interupt is asserted if ERR is set.

>>    Which is not its business to test. I think you should remove that above 
>>check -- if there's INTRQ asserted, then it's asserted. I wonder if BMIDE 
>>interrupt bit gets set in that case (suspecting it's not)...

> Well, let me explain a bit.  The datasheed say I should wait _both_
> XFERINT and HOST interrupt.  So, if only one of them was asserted, I

    Since this is SFF-8038i compatible, you should first check if the spec'ed
interrupt status bit (called IDE_INT here) is set. If it isn't [always] get
set when it should, you may check for other interrupt bits (XFEREND/HOST/etc.)
and take the necessary measures if you detect interrupt on them.

> mask it and wait another one.  But on the error case, only HOST was
> asserted and XFERINT was never asserted.

    And I suspect that IDE_INT also doesn't get set, right? The check for 
ERR=1 however is not needed. If the drive does assert its interrupt signal 
(INTRQ), it knows better why.

> Then I could not exit from "waiting another one" state, until timeout.

    Well, at least most of the other [PCI] drivers will wait for timeout in 
the case of the DMA status register bit 2 (IDE_INT here) not set -- despite 
some IDE chips do have bits indicating the INTRQ status from IDE bus. But 
usually, INTRQ still comes thru to this bit even if a command ends in error... 
This isn't the case here?

MBR, Sergei