Re: [PATCH] 2.5.8 IDE 36

Martin Dalecki
2002-04-16T10:22:32Z

Norbert Kiesel wrote:
> On Tue, 2002-04-16 at 01:21, Martin Dalecki wrote:
>
>>Norbert Kiesel wrote:
>>
>>>Hi,
>>>
>>>while trying to understand recent kernel changes I stumbled over
>>>the following patch to
>>>
>>>diff -urN linux-2.5.8/drivers/ide/ide.c linux/drivers/ide/ide.c
>>>--- linux-2.5.8/drivers/ide/ide.c Tue Apr 16 06:01:07 2002
>>>+++ linux/drivers/ide/ide.c Tue Apr 16 05:38:37 2002
>>>
>>>...
>>> while (i > 0) {
>>>- u32 buffer[16];
>>>- unsigned int wcount = (i > 16) ? 16 : i;
>>>- i -= wcount;
>>>- ata_input_data (drive, buffer, wcount);
>>>+ u32 buffer[SECTOR_WORDS];
>>>+ unsigned int count = (i > 1) ? 1 : i;
>>>+
>>>+ ata_read(drive, buffer, count * SECTOR_WORDS);
>>>+ i -= count;
>>> }
>>> }
>>>...
>>>
>>>While the old code called ata_input_read() with [0:16] as last param,
>>>the new code calls the (renamed) ata_read() with either 0 or 16. Also,
>>>the new code loops "i" times while the old code looped "i/16+1" times.
>>>Was this intended or should the patch better read like:
>>>
>>>...
>>> while (i > 0) {
>>>- u32 buffer[16];
>>>- unsigned int wcount = (i > 16) ? 16 : i;
>>>- i -= wcount;
>>>- ata_input_data (drive, buffer, wcount);
>>>+ u32 buffer[SECTOR_WORDS];
>>>+ unsigned int count = max(i, SECTOR_WORDS);
>>>+
>>>+ ata_read(drive, buffer, count);
>>>+ i -= count;
>>> }
>>> }
>>>...
>>>
>>>so long
>>
>>It's fine as it is I think. Please look up at the initialization of i.
>>I have just divded the SECTROT_WORDS (== 16) factor out
>>of all the places above ata_read.
>>
>
>
> You are right (assuming SECTOR_WORDS == 16. I was looking it up in
> 2.4.18 where SECTOR_WORDS is 512/4 == 128). However, the new code looks
> overly complicated (at least for me, easily proven by my wrong first
> email :-), given that count is now always == 1. Would the following not
> be nicer?
>
> int i;
>
> if (drive->type != ATA_DISK)
> return;
>
> for (i = min(drive->mult_count, 1); i > 0; i--) {
> u32 buffer[SECTOR_WORDS];
>
> ata_read(drive, buffer, SECTOR_WORDS);
> }
>
> (This of course assumes that drive->mult_count is always non-negative)

Yes this looks nicer. Would you mind to test it and drop me
a patch?