[U-Boot] [PATCH] mx6: fsl_esdhc: Fix waiting for DMA operation completion

[Fleming Andy-AFLEMING]

On Apr 4, 2013, at 1:41 PM, Eric Nelson wrote:

> Hi Andrew,
> 
> On 04/04/2013 11:03 AM, Gabbasov, Andrew wrote:
>> Hi Eric,
>> 
>>> From: Eric Nelson [eric.nelson at boundarydevices.com]
>>> Sent: Thursday, April 04, 2013 03:47
>>> To: Gabbasov, Andrew
>>> Cc: u-boot at lists.denx.de; Behme, Dirk - Bosch; Fabio Estevam
>>> Subject: Re: [U-Boot] [PATCH] mx6: fsl_esdhc: Fix waiting for DMA operation completion
>>> 
>> 
>> So, do you think the latter (modified) loop condition
>> 
>>      } while (!(irqstat & IRQSTAT_TC) || !(irqstat & IRQSTAT_DINT) ||
>>            (esdhc_read32(&regs->prsstat) & PRSSTAT_DLA));
>> 
>> will be correct?
>> 
> 
> I think the right thing to do is eliminate the DLA test entirely,
> so the loop condition can be simplified to something like this:
> 
> #define TRANSFER_COMPLETE (IRQSTAT_TC|IRQSTAT_DINT)
> 
> 	do {
> 		...
> 	} while (TRANSFER_COMPLETE != (irqstat&TRANSFER_COMPLETE));


That looks right to me. I have been known to mistakenly write loops that are supposed to wait for two conditions to only wait for one of those. Apparently I need remedial boolean logic lessons.


> 
> If there is another part that needs to bail out on PRSSTAT_DLA,
> it seems that the affected part should be the one with the #ifdef


I don't think we need a special case. Just correct logic. :/

Andy