[U-Boot] [PATCH 03/11] st_smi: Return error in case TFF is not set

[Amit Virdi]

Hello Stefan,

On 2/27/2012 3:56 PM, Stefan Roese wrote:
> On Friday 24 February 2012 13:23:06 Amit Virdi wrote:
>> Curently the code makes wrong assumption that the Transfer finished flag
>> shall be set within the stipulated time. However, there may occur a
>> scenario in which the TFF flag is not set. Return error in that case.
>>
>> Signed-off-by: Vipin Kumar<vipin.kumar at st.com>
>> Signed-off-by: Amit Virdi<amit.virdi at st.com>
>> ---
>>   drivers/mtd/st_smi.c |   22 ++++++++++++++--------
>>   1 files changed, 14 insertions(+), 8 deletions(-)
>>
>> diff --git a/drivers/mtd/st_smi.c b/drivers/mtd/st_smi.c
>> index 82f1fe1..ec19b0d 100644
>> --- a/drivers/mtd/st_smi.c
>> +++ b/drivers/mtd/st_smi.c
>> @@ -58,13 +58,15 @@ static struct flash_dev flash_ids[] = {
>>    *
>>    * Wait until TFF is set in status register
>>    */
>> -static void smi_wait_xfer_finish(int timeout)
>> +static int smi_wait_xfer_finish(int timeout)
>>   {
>> -	while (timeout--) {
>> +	do {
>>   		if (readl(&smicntl->smi_sr)&  TFF)
>> -			break;
>> +			return 0;
>>   		udelay(1000);
>> -	}
>> +	} while (timeout--);
>> +
>> +	return -1;
>
> Somewhat unrelated to the patch topic, but I don't really like this kind of
> timeout loops. Since it always adds at least 1ms delay after initial failing
> test. Better use something like this:
>
> static int smi_wait_xfer_finish(int timeout)
> {
> 	ulong start = get_timer(0);
>
> 	while (get_timer(start)<  timeout) {
> 		if (readl(&smicntl->smi_sr)&  TFF)
> 			return 0;
>
> 		/* Try again after 100usec */
> 		udelay(100);
> 	}
>
> 	return -1;
> }
>
> You could tune this udelay(100) down more or even remove it completely.
>
> But such a change could be done in a addon cleanup patch, changing all timeout
> loops this way. I suggest you take a look at my version, here these loops are
> changes. In the designware networking driver as well, iirc.
>

Thanks for pointing out. In a separate cleanup patch, I shall be 
changing all the timeout loops for smi driver. I'll check other ST 
drivers too and change the timer implementation there too.

Regards
Amit Virdi