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Groups > linux.kernel > #1279315
| From | Finn Thain <fthain@telegraphics.com.au> |
|---|---|
| Newsgroups | linux.kernel |
| Subject | Re: [PATCH 22/71] ncr5380: Eliminate selecting state |
| Date | 2015-11-29 11:30 +0100 |
| Message-ID | <qA7p0-4Xu-15@gated-at.bofh.it> (permalink) |
| References | (1 earlier) <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> <qA6sW-4nz-7@gated-at.bofh.it> |
| Organization | linux.* mail to news gateway |
On Sun, 29 Nov 2015, Geert Uytterhoeven wrote:
> 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,
Sure but the time-out condition isn't supposed to be precise.
Plus/minus a jiffy is no problem. Plus/minus a second is no good.
> as it may take much longer. Always compare with an maximum end time
> instead.
That can't work with interrupts disabled, which was the problem I was
trying to solve by use of loops_per_jiffy.
NCR5380_poll_politely() in mainline doesn't work with interrupts disabled
either, hence patch 21.
>
> 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".
Interrupts may be disabled during that loop also. Please refer to (and/or
respond to) patch 21, "ncr5380: Sleep when polling, if possible", in which
these changes were made.
--
>
> Gr{oetje,eeting}s,
>
> Geert
>
--
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[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
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