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Re: [PATCH] ahci: Improve error handling

From: Daniel Kiper
Subject: Re: [PATCH] ahci: Improve error handling
Date: Mon, 29 Jan 2018 13:16:44 +0100
User-agent: Mutt/1.3.28i

On Tue, Jan 23, 2018 at 01:00:56PM +0100, Daniel Kiper wrote:
> On Fri, Jan 19, 2018 at 02:13:29PM +0100, Stefan Fritsch wrote:
> > From: Stefan Fritsch <address@hidden>
> >
> > Check the error bits in the interrupt status register. According to the
> > AHCI 1.2 spec, "Interrupt sources that are disabled (?0?) are still
> > reflected in the status registers.", so this should work even though
> > grub uses polling
> >
> > This fixes the following problem on a Fujitsu E744 laptop:
> >
> > Sometimes there is a very long delay (up to several minutes) when
> > booting from hard disk. It seems accessing the DVD drive (which has no
> > disk inserted) sometimes fails with some errors, which leads to each
> > access being stalled until the 20s timeout triggers. This seems to
> > happen when grub is trying to read filesystem/partition data.
> >
> > The problem is that the command_issue bit that is checked in the loop is
> > only reset if the "HBA receives a FIS which clears the BSY, DRQ, and ERR
> > bits for the command", but the ERR bit is never cleared. Therefore
> > command_issue is never reset and grub waits for the timeout.
> >
> > The relevant bit in our case is the Task File Error Status (TFES), which
> > is equivalent to the ERR bit 0 in tfd. But this patch also checks
> > the other error bits except for the "Interface non-fatal error status"
> > bit.
> >
> > Signed-off-by: Stefan Fritsch <address@hidden>
> Reviewed-by: Daniel Kiper <address@hidden>
> If there are no objections I will apply this by the end of this week.




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