Re: [PATCH v3 0/4] g_NCR5380: PDMA fixes and cleanup

From	Finn Thain <fthain@telegraphics.com.au>
Newsgroups	linux.kernel
Subject	Re: [PATCH v3 0/4] g_NCR5380: PDMA fixes and cleanup
Date	2017-06-28 06:20 +0200
Message-ID	<tXcCl-1Yd-9@gated-at.bofh.it> (permalink)
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On Tue, 27 Jun 2017, Ondrej Zary wrote:

> On Tuesday 27 June 2017 14:42:29 Finn Thain wrote:
> 
> > > ... it triggers sometimes: the value is 1 instead of 0. As we use 
> > > only 16-bit writes, I don't see how the value could ever be odd. 
> > > Looks like a bug in the chip. The index register corrupts during the 
> > > transfer, not after IRQ or timeout. The same check at beginning of 
> > > pwrite() did not trigger.
> >
> > Are you reading this register at the right moment? Have you tried 
> > waiting for it to reach zero, as in,
> >
> > 	if (NCR5380_poll_politely(hostdata, 13, 0xff, 0, HZ / 64) < 0)
> > 		/* printk, reset etc */;
> 
> I have not but will try (expecting that it will not change by itself).
> 

Now that I know that it is the byte at the beginning of the block that 
went missing, I agree that there's no point waiting for the byte count to 
change.

I've included a patch with your 512 B limit in v4.

Thanks.

> > Even if this is a reliable way to detect a short transfer, it would be 
> > nice to know the root cause. But I'm being unrealistic: the DTC436 
> > vendor never responded to my requests for technical documentation.
> 
> According to the data corruption observed, it's not a short transfer. 
> The corruption is always the same: one byte missing at the beginning of 
> a 128 B block. It happens only with slow Quantum LPS 240 drive, not with 
> faster IBM DORS-32160.
> 

--

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[PATCH v3 0/4] g_NCR5380: PDMA fixes and cleanup Finn Thain <fthain@telegraphics.com.au> - 2017-06-26 09:40 +0200
  [PATCH v3 1/4] g_NCR5380: Fix PDMA transfer size Finn Thain <fthain@telegraphics.com.au> - 2017-06-26 09:40 +0200
  [PATCH v3 2/4] g_NCR5380: End PDMA transfer correctly on target  disconnection Finn Thain <fthain@telegraphics.com.au> - 2017-06-26 09:40 +0200
  Re: [PATCH v3 0/4] g_NCR5380: PDMA fixes and cleanup Ondrej Zary <linux@rainbow-software.org> - 2017-06-26 21:30 +0200
    Re: [PATCH v3 0/4] g_NCR5380: PDMA fixes and cleanup Finn Thain <fthain@telegraphics.com.au> - 2017-06-27 03:50 +0200
      Re: [PATCH v3 0/4] g_NCR5380: PDMA fixes and cleanup Ondrej Zary <linux@rainbow-software.org> - 2017-06-27 20:50 +0200
        Re: [PATCH v3 0/4] g_NCR5380: PDMA fixes and cleanup Finn Thain <fthain@telegraphics.com.au> - 2017-06-28 06:20 +0200
    Re: [PATCH v3 0/4] g_NCR5380: PDMA fixes and cleanup Ondrej Zary <linux@rainbow-software.org> - 2017-06-27 08:30 +0200
      Re: [PATCH v3 0/4] g_NCR5380: PDMA fixes and cleanup Michael Schmitz <schmitzmic@gmail.com> - 2017-06-27 10:40 +0200
        Re: [PATCH v3 0/4] g_NCR5380: PDMA fixes and cleanup Finn Thain <fthain@telegraphics.com.au> - 2017-06-27 15:00 +0200
      Re: [PATCH v3 0/4] g_NCR5380: PDMA fixes and cleanup Finn Thain <fthain@telegraphics.com.au> - 2017-06-27 14:50 +0200
        Re: [PATCH v3 0/4] g_NCR5380: PDMA fixes and cleanup Ondrej Zary <linux@rainbow-software.org> - 2017-06-27 18:10 +0200
          Re: [PATCH v3 0/4] g_NCR5380: PDMA fixes and cleanup Finn Thain <fthain@telegraphics.com.au> - 2017-06-28 06:20 +0200

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