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Date: Sun, 29 Nov 2015 10:27:25 +0100 From: Geert Uytterhoeven <geert@...ux-m68k.org> To: Finn Thain <fthain@...egraphics.com.au> Cc: Ondrej Zary <linux@...nbow-software.org>, "James E.J. Bottomley" <JBottomley@...n.com>, Michael Schmitz <schmitzmic@...il.com>, "Linux/m68k" <linux-m68k@...r.kernel.org>, scsi <linux-scsi@...r.kernel.org>, "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org> Subject: Re: [PATCH 22/71] ncr5380: Eliminate selecting state Hi Finn, On Thu, Nov 26, 2015 at 11:32 PM, Finn Thain <fthain@...egraphics.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@...ux-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@...r.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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