Groups | Search | Server Info | Keyboard shortcuts | Login | Register [http] [https] [nntp] [nntps]
Groups > linux.kernel > #1279305
| From | Geert Uytterhoeven <geert@linux-m68k.org> |
|---|---|
| Newsgroups | linux.kernel |
| Subject | Re: [PATCH 22/71] ncr5380: Eliminate selecting state |
| Date | 2015-11-29 10:30 +0100 |
| Message-ID | <qA6sW-4nz-7@gated-at.bofh.it> (permalink) |
| References | <qw6Bc-vx-5@gated-at.bofh.it> <qyQgy-3rg-3@gated-at.bofh.it> <qz1Yl-3Qr-1@gated-at.bofh.it> <qzayB-ZY-3@gated-at.bofh.it> <qzdmO-2Nc-15@gated-at.bofh.it> |
| Organization | linux.* mail to news gateway |
Hi Finn,
On Thu, Nov 26, 2015 at 11:32 PM, Finn Thain <fthain@telegraphics.com.au> wrote:
>> The timekeeping warning does not appear when all 71 patches are applied.
>> Reverse-bisected it - the warning disappears after:
>> [PATCH 50/71] ncr5380: Change instance->host_lock to hostdata->lock
>>
>
> Makes sense. I think that this should solve the problem:
>
> Index: linux/drivers/scsi/NCR5380.c
> ===================================================================
> --- linux.orig/drivers/scsi/NCR5380.c 2015-11-27 09:21:40.000000000 +1100
> +++ linux/drivers/scsi/NCR5380.c 2015-11-27 09:25:36.000000000 +1100
> @@ -230,7 +230,7 @@ static int NCR5380_poll_politely2(struct
> unsigned long n;
>
> /* Busy-wait for up to 1 jiffy */
> - n = loops_per_jiffy;
> + n = 1 + loops_per_jiffy / 10;
> do {
> if ((NCR5380_read(reg1) & bit1) == val1)
> return 0;
This still heavily depends on the processing time spent in NCR5380_read().
You should never use a value derived from loops_per_jiffy for a non-empty loop,
as it may take much longer. Always compare with an maximum end time instead.
E.g.:
end = jiffies + 2; /* 1 jiffie + 1 safeguard */
do {
if ((NCR5380_read(reg1) & bit1) == val1)
return 0;
cpu_relax();
} while (time_before(jiffies, end);
And a similar loop for "Busy-wait for up to 20 ms".
Gr{oetje,eeting}s,
Geert
--
Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- geert@linux-m68k.org
In personal conversations with technical people, I call myself a hacker. But
when I'm talking to journalists I just say "programmer" or something like that.
-- Linus Torvalds
--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@vger.kernel.org
More majordomo info at http://vger.kernel.org/majordomo-info.html
Please read the FAQ at http://www.tux.org/lkml/
Back to linux.kernel | Previous | Next — Previous in thread | Next in thread | Find similar | Unroll thread
[PATCH 22/71] ncr5380: Eliminate selecting state Finn Thain <fthain@telegraphics.com.au> - 2015-11-18 10:10 +0100
Re: [PATCH 22/71] ncr5380: Eliminate selecting state Ondrej Zary <linux@rainbow-software.org> - 2015-11-24 20:10 +0100
Re: [PATCH 22/71] ncr5380: Eliminate selecting state Finn Thain <fthain@telegraphics.com.au> - 2015-11-25 04:20 +0100
Re: [PATCH 22/71] ncr5380: Eliminate selecting state Ondrej Zary <linux@rainbow-software.org> - 2015-11-25 23:00 +0100
Re: [PATCH 22/71] ncr5380: Eliminate selecting state Finn Thain <fthain@telegraphics.com.au> - 2015-11-26 11:30 +0100
Re: [PATCH 22/71] ncr5380: Eliminate selecting state Ondrej Zary <linux@rainbow-software.org> - 2015-11-26 20:40 +0100
Re: [PATCH 22/71] ncr5380: Eliminate selecting state Finn Thain <fthain@telegraphics.com.au> - 2015-11-26 23:40 +0100
Re: [PATCH 22/71] ncr5380: Eliminate selecting state Ondrej Zary <linux@rainbow-software.org> - 2015-11-29 00:20 +0100
Re: [PATCH 22/71] ncr5380: Eliminate selecting state Finn Thain <fthain@telegraphics.com.au> - 2015-11-29 01:50 +0100
Re: [PATCH 22/71] ncr5380: Eliminate selecting state Ondrej Zary <linux@rainbow-software.org> - 2015-11-29 10:20 +0100
Re: [PATCH 22/71] ncr5380: Eliminate selecting state Geert Uytterhoeven <geert@linux-m68k.org> - 2015-11-29 10:30 +0100
Re: [PATCH 22/71] ncr5380: Eliminate selecting state Finn Thain <fthain@telegraphics.com.au> - 2015-11-29 11:30 +0100
Re: [PATCH 22/71] ncr5380: Eliminate selecting state Geert Uytterhoeven <geert@linux-m68k.org> - 2015-11-29 15:00 +0100
Re: [PATCH 22/71] ncr5380: Eliminate selecting state Finn Thain <fthain@telegraphics.com.au> - 2015-11-30 03:20 +0100
csiph-web